3-i

CHAPTER 3. MARKET AND TECHNOLOGY ASSESSMENT

TABLE OF CONTENTS 

3.1 INTRODUCTION ........................................................................................................... 3-1

3.1.1 Definitions............................................................................................................ 3-1

3.1.1.1 Metal Halide Lamp Fixture...................................................................... 3-1

3.1.1.2 Metal Halide Lamp .................................................................................. 3-1

3.1.1.3 Metal Halide Lamp Ballast ...................................................................... 3-2

3.1.1.4 Ballast and Electronic Ballast .................................................................. 3-2

3.1.1.5 Probe-Start Metal Halide Ballast ............................................................. 3-2

3.1.1.6 Pulse-Start Metal Halide Ballast.............................................................. 3-2

3.1.1.7 Ballast Efficiency..................................................................................... 3-2

3.2 MARKET ASSESSMENT.............................................................................................. 3-3

3.2.1 Trade Associations............................................................................................... 3-3

3.2.2 Manufacturers and Market Share......................................................................... 3-4

3.2.2.1 Small Businesses...................................................................................... 3-6

3.2.3 Regulatory Programs ........................................................................................... 3-7

3.2.3.1 Federal Energy Conservation Standards.................................................. 3-7

3.2.3.2 California Energy Commission................................................................ 3-9

3.2.3.3 Canadian Energy Efficiency Standards ................................................... 3-9

3.2.4 Non-Regulatory Initiatives................................................................................. 3-10

3.2.4.1 Federal Energy Management Program .................................................. 3-10

3.2.4.2 ENERGY STAR.................................................................................... 3-11

3.2.4.3 Northeast Energy Efficiency Partnerships............................................. 3-11

3.2.5 Alternative Fixture Efficiency Metrics.............................................................. 3-11

3.2.5.1 Fitted Target Efficacy ............................................................................ 3-12

3.2.5.2 Target Efficacy Rating........................................................................... 3-12

3.2.6 Historical Shipments.......................................................................................... 3-14

3.2.6.1 HID Lamp Fixtures Shipments.............................................................. 3-14

3.2.6.2 Estimated Historical Metal Halide Lamp Fixtures Shipments .............. 3-17

3.3 TECHNOLOGY ASSESSMENT.................................................................................. 3-18

3.3.1 Metal Halide Lamp Fixtures Overview ............................................................. 3-18

3.3.1.1 Basic Metal Halide Lamp Fixture Structure .......................................... 3-18

3.3.1.2 Indoor Fixtures....................................................................................... 3-19

3.3.1.3 Outdoor Fixtures.................................................................................... 3-21

3.3.1.4 Energy Related Fixture Options............................................................. 3-26

3.3.2 Basic Structure of Metal Halide Lamps............................................................. 3-28

3.3.3 Metal Halide Lamp Ballast Overview ............................................................... 3-30

3.3.3.1 Ballast Efficiency................................................................................... 3-30

3.3.3.2 Starting Method ..................................................................................... 3-30

3.3.3.3 Power Factor.......................................................................................... 3-31

3.3.3.4 Total Harmonic Distortion..................................................................... 3-32

3.3.3.5 Ballast Factor ......................................................................................... 3-32

3.3.3.6 Electromagnetic Interference ................................................................. 3-32
3-ii

3.3.3.7 Transient Susceptibility ......................................................................... 3-33

3.3.3.8 Fitted Form............................................................................................. 3-33

3.3.3.9 Dimming ................................................................................................ 3-33

3.3.3.10 Magnetic Ballasts.............................................................................. 3-34

3.3.3.11 Electronic Ballasts............................................................................. 3-36

3.3.4 Metal Halide Lamp Ballast Technology Options .............................................. 3-39

3.3.4.1 Magnetic Ballasts................................................................................... 3-39

3.3.4.2 Electronic Ballasts ................................................................................. 3-40

3.4 EQUIPMENT CLASSES .............................................................................................. 3-42

3.4.1 Rated Lamp Wattage.......................................................................................... 3-44

3.4.2 Input Voltage ..................................................................................................... 3-44

3.4.3 Maximum Number of Lamps Operated............................................................. 3-45

3.4.4 Lamp Starting Method ....................................................................................... 3-45

3.4.5 Electronic Configuration and Circuit Type........................................................ 3-46

3.4.6 Equipment Classes Summary ............................................................................ 3-47

LIST OF TABLES

Table 3.2.1 Proposed Canadian Standards for Metal Halide Lamp Ballasts............................. 3-10

Table 3.2.2 Federal Energy Management Program Efficiency Recommendation .................... 3-11

Table 3.2.3 U.S. Census Shipments of HID Lamp Fixtures from 1993 to 2001 ....................... 3-16

Table 3.2.1 Estimated Historical Shipments of Metal Halide Lamp Fixtures from 1993 to 2001 3-

17

Table 3.2.2 Estimated Historical Shipments of Metal Halide Lamp Fixtures from 2002 to 2009 3-

17

Table 3.3.1 Basic Building Blocks of a Metal Halide Lamp Ballast and Associated 

Characteristics............................................................................................................................ 3-37

Table 3.4.1 EPCA Equipment Categories Established by EISA 2007 for Metal Halide Lamp 

Fixtures (by Ballast Type and Lamp Wattage).......................................................................... 3-43

Table 3.4.2 Equipment Classes for Metal Halide Lamp Ballasts.............................................. 3-47

LIST OF FIGURES

Figure 3.2.1 2001 HID Fixtures Market Share by Segment ...................................................... 3-15

Figure 3.3.1 Metal Halide Lamp Fixture Structure.................................................................... 3-19

Figure 3.3.2 Example of Recessed Downlight Metal Halide Lamp Fixture.............................. 3-20

Figure 3.3.3 Example of High Bay Metal Halide Lamp Fixture ............................................... 3-20

Figure 3.3.4 Example of Low Bay Metal Halide Lamp Fixture................................................ 3-21

Figure 3.3.5 Example of Area/Roadway Metal Halide Lamp Fixture....................................... 3-22

Figure 3.3.6 Example of Bollard Metal Halide Lamp Fixture................................................... 3-22

Figure 3.3.7 Example of Canopy Metal Halide Lamp Fixture .................................................. 3-23
3-iii

Figure 3.3.8 Example of Cobrahead Metal Halide Lamp Fixture ............................................. 3-23

Figure 3.3.9 Example of Floodlight Metal Halide Lamp Fixture.............................................. 3-24

Figure 3.3.10 Example of Parking Garage Metal Halide Lamp Fixture.................................... 3-24

Figure 3.3.11 Example of Post-Top Metal Halide Lamp Fixture.............................................. 3-25

Figure 3.3.12 Example of Sports Lighting Metal Halide Lamp Fixture.................................... 3-25

Figure 3.3.13 Example of Wallpack Metal Halide Lamp Fixture ............................................. 3-26

Figure 3.3.14 Core and Coil Assembly of a Magnetic Ballast .................................................. 3-35

Figure 3.3.15 Electronic Metal Halide Ballast Block Diagram................................................. 3-37
3-1

CHAPTER 3. 

3.1 INTRODUCTION

MARKET AND TECHNOLOGY ASSESSMENT

This chapter details the market and technology assessment that the U.S. Department of 

Energy (DOE) has conducted in support of the ongoing energy conservation standards 

rulemakings for metal halide lamp fixtures. This rulemakings is mandated by the Energy Policy 

and Conservation Act (EPCA), as amended by Energy Independence and Security Act of 2007

(EISA 2007), and are effective for metal halide lamp fixtures manufactured during and after 

2015.

This chapter consists of three sections: the market assessment, the technology 

assessment, and equipment classes. The market assessment provides an overall picture of the 

market for the equipment concerned, including the nature of the equipment, industry structure, 

and manufacturer market shares; regulatory and non-regulatory efficiency improvement 

programs; and market trends and quantities of equipment sold. The technology assessment 

identifies a preliminary list of technologies to consider in the screening analysis. The equipment 

classes section discusses the equipment classes DOE considered using for this rulemaking and 

how they were developed.

The information DOE gathers from the market and technology assessment serves as 

resource material for use throughout the rulemaking. DOE considers both quantitative and 

qualitative information from publicly available sources and interested parties. 

3.1.1 Definitions

EISA 2007 added definitions to EPCA for metal halide lamp fixture and associated terms. 

DOE codified the statutory definitions and definitions of supplementary terms for metal halide 

lamp fixtures in the Code of Federal Regulations (CFR). 10 CFR 431.322. The following 

sections describe, in greater detail, EPCA definitions for metal halide lamp fixture, metal halide 

lamp, metal halide lamp ballast, ballast, electronic ballast, probe-start metal halide ballast, pulsestart metal halide ballast, and ballast efficiency. These terms help define the scope of energy 

conservation standards for metal halide lamp fixtures. Appendix 3A includes a complete list of 

terms and their definitions. 

3.1.1.1 Metal Halide Lamp Fixture

Section 321(64) of EPCA broadly defines metal halide lamp fixtures as: “light fixture for 

general lighting application designed to be operated with a metal halide lamp and a ballast for a 

metal halide lamp.” (42 U.S.C. § 6291(64))

3.1.1.2 Metal Halide Lamp

Section 321(63) of EPCA defines metal halide lamp as: “a high intensity discharge lamp 

in which the major portion of the light is produced by radiation of metal halides and their 

products of dissociation, possibly in combination with metallic vapors.” (42 U.S.C. § 6291(63))
3-2

3.1.1.3 Metal Halide Lamp Ballast

Section 321(62) of EPCA defines metal halide lamp ballast as: “a ballast used to start and 

operate metal halide lamps.” (42 U.S.C. § 6291(62))

3.1.1.4 Ballast and Electronic Ballast

Section 321 of EPCA defines ballast as: “a device used with an electric discharge lamp to 

obtain necessary circuit conditions (voltage, current, and waveform) for starting and operating.” 

(42 U.S.C. § 6291(58)) Electronic ballast is defined as: “a device that uses semiconductors as the 

primary means to control lamp starting and operation.” (42 U.S.C. § 6291(60))

3.1.1.5 Probe-Start Metal Halide Ballast

Sections 321(65)(A) and (B) of EPCA define probe-start metal halide ballast as: “a 

ballast that—

(A) starts a probe-start metal halide lamp that contains a third starting electrode (probe) in 

the arc tube; and 

(B) does not generally contain an igniter but instead starts lamps with high ballast open 

circuit voltage.”

(42 U.S.C. 6291(65))

3.1.1.6 Pulse-Start Metal Halide Ballast

Sections 321(66)(A) and (B) of EPCA define pulse-start metal halide ballast as:

“(A) In general.— The term “pulse-start metal halide ballast” means an electronic or 

electromagnetic ballast that starts a pulse-start metal halide lamp with high voltage 

pulses. 

(B) Starting process.— For the purpose of subparagraph (A)—

(i) lamps shall be started by first providing a high voltage pulse for ionization of 

the gas to produce a glow discharge; and 

(ii) to complete the starting process, power shall be provided by the ballast to 

sustain the discharge through the glow-to-arc transition.”

(42 U.S.C. 6291(66))

3.1.1.7 Ballast Efficiency

Section 321(59)(A) of EPCA (42 U.S.C. § 6291(59)(A)) defines ballast efficiency (BE) 

as: “in the case of a high intensity discharge fixture, the efficiency of a lamp and ballast 

combination, expressed as a percentage, and calculated in accordance with the following 

formula: Efficiency = Pout/Pin.”

Section 321(59)(B) of EPCA clarifies the definition of the calculations for ballast 

efficiency or Pout/Pin by defining the following:
3-3

“(i) Pout shall equal the measured operating lamp wattage;

(ii) Pin shall equal the measured operating input wattage;”

(42 U.S.C. § 6291(59)(B))

3.2 MARKET ASSESSMENT

The following market assessment identifies the manufacturer trade association and 

domestic manufacturers of metal halide lamp fixtures and ballast; discusses manufacturer market 

share, regulatory programs, and non-regulatory initiatives; defines equipment classes; provides 

historical shipment data, shipment projections, and equipment lifetime estimates; and 

summarizes market performance data.

3.2.1 Trade Associations

The National Electrical Manufacturers Association (NEMA) is the trade association for 

metal halide lamp fixtures and ballasts. NEMA’s Lighting Systems Division is one of eight 

product divisions. The division’s 47 member companies comprise 85 to 95% of the U.S. 

commercial and industrial market, as well as large portions of the institutional and educational 

markets.1 In addition to metal halide lamp fixtures and ballasts, NEMA’s Lighting Systems 

Division also oversees products such as metal halide lamps, other high intensity discharge (HID) 

equipment, fluorescent lamps and ballasts, emergency lighting technologies, lighting controls, 

luminairesa

• advising DOE and executive agencies on lighting research and market transformation 

needs;

in general, and solid state lighting. NEMA provides an organization through which 

manufacturers of lighting equipment can work together on projects that affect their industry and 

business. NEMA’s activities relating to energy efficiency include:

• engaging in legislative work on energy and lighting issues;

• monitoring energy-efficiency rulemakings and standards affecting lighting products by 

federal and state agencies;

• promoting the national voluntary luminaire rating and information program under the 

National Lighting Collaborative; 

• supporting adoption of 1999 American Society of Heating, Refrigerating and AirConditioning Engineers (ASHRAE) and the Illuminating Engineering Society of North 

America(IESNA) 90.1 lighting provisions (hereafter ASHRAE/IESNA 90.1);

• working with market transformation and environmental groups to advance market use of 

energy-efficient lighting technologies; 

 a In this document DOE is using the terms “luminaire” and “fixture” interchangeably.
3-4

• advising DOE and the U.S. Environmental Protection Agency (EPA) on ENERGY 

STAR®

• advocating market-based approaches to enhance the use and penetration of energyefficient technologies.

Buildings and ENERGY STAR voluntary product labeling programs; and

2

3.2.2 Manufacturers and Market Share

The fixture market is composed of several domestic and international manufacturers. The 

following list contains the names of manufacturers that are part of the Luminaire Section of 

NEMA:

• Acuity Brands Lighting

• Arcalux Corporation

• Cooper Controls

• Cooper Lighting

• Emerson/EGS Electrical Group

• GE Consumer and Industrial of General Electric, Inc. (hereafter, “GE”)

• Genlyte Group/Lightolier/Gardco – Philips Lighting

• Holophane

• Hubbell Lighting

• Inter-Global, Inc.

• Juno Lighting Group

• Light One Inc.

• Lithonia Lighting

• National Cathode Corp

• OSRAM SYLVANIA of Siemens AG (hereafter “Osram Sylvania”)

• Ruud Lighting Inc.

• Technical Consumer Products, Inc.

• Thomas & Betts Corporation

• Philips

• Venture Lighting International

Several manufacturers are owned by parent companies that make up the majority of the 

market. For covered equipment, the majority of the metal halide fixtures market is held by 

NEMA members and non-members, which include:

• GE 

• Osram Sylvania

• Philips Lighting

• Acuity Brands Lighting

• Cooper Lighting

• Hubbell Lighting

• Juno Lighting Group

• Venture Lighting International
3-5

Additional metal halide lamp fixtures manufacturers include:

• ABS Lighting

• Access Fixtures

• Acting Chile-Appleton 

Agency Southern Cone

• Arcalux

• Architectural Details, Inc

• Architectural Lighting Works

• Atlantic Lighting, Inc.

• Atlas Ligthing

• Rig-A-Lite

• Baero

• Bega

• Babican Architectural 

Products

• Barn Light Electric

• Better Designed Lighting

• C.W. Cole & Company

• CD Lighting

• CGF Design Inc

• Con-Tech Lighting

• Custom Metalcraft

• Deco Lighting

• Deep Roof Lighting 

• DMF Lighting Solutions

• Dynamic Lighting Solutions

• Amerlux Lighting Solutions

• Eclipse Lighting

• EECOL Electric

• Elite Lighting

• Energie Lighting

• Energy Focus, Inc 

• Engineering Products 

Company 

• Eureka Lighting

• EUTRAC Corp.

• Focal Point LLC

• Villa Lighting Supply

• Visa Lighting

• Vision3 Lighting

• Visionaire Lighting

• W2 Architectural Lighting

• WAC Lighting

• Welch Lighting

• Will-Burt

• G Lighting

• GSS Global Solutions

• Healthcare Lighting

• HessAmerica

• Hunza Lighting USA

• ICOF Inc

• ICOF International

• Insight Lighting

• Intense Lighting

• K.J. Lighting Sales

• Kenall Manufacturing

• Kirling Company

• LDPI Inc

• Legion Lighting Company

• LightGuard

• Lighting Nelson & Garrett

• Lighting Services

• Light Makers

• Litelab

• LITON

• LSI Industries

• Lumascape USA

• Lumca

• Lumenelle

• Lumenform Industries

• Lumenton Lighting

• Luminis

• Manning Lighting

• Martin Professional

• Metalumen

• Meyda Custom Lighting

• Mohandesi Mahshid 

Sepahan

• Moutain States Lighting

• MP Lighting

• Neonlite Electronic & 

Lighting

• Paramount Industries

• Pauluhn

• Phoenix Products

• Pinnacle Architectural 

Lighting

• Prisma Architectural 

Lighting

• Qualite Sports Lighting

• Rambusch Lighting

• Reggiani Lighting

• Reyk Lighting

• Ruud Lighting Canada

• Satco Products

• Schreder Lighting USA

• Selux Corporation

• Sheed Lighting

• Sheedlight

• Sleeve Off Design

• Spectrum Lighting

• SPI Lighting

• Spot on Lighting

• Spring City Electrical Mfg 

Co

• Stanpro Lighting Systems

• Sternberg Lighting Systems

• StressCrete Group

• Swivelier

• Tech Lighting

• Teddico

• The Lighting Quotient

• The Pennsylvania Globe 

Gaslight Company

• TPR Enterprises

• US Architectural Lighting

The following list contains the names of manufacturers that produce metal halide lamp 

ballasts:

• Advance Transformer (Philips)
3-6

• AMF Lighting

• Etlin

• Fulham

• GE

• Hatch Transformer

• Howard Industries

• Lightec

• Metrolight

• Osram Sylvania

• Power Select

• Robertson Worldwide

• SOLA

• Sunpark

• Ultrasave Lighting Ltd.

• Universal Lighting Technologies

• Venture Lighting International

• Vossloh-Schwabe

Five manufacturers hold the majority of the domestic market share of metal halide lamp ballasts 

• GE

• Osram Sylvania

• Advance Transformer of Philips Lighting (hereafter “Advance”)

• Universal Lighting Technologies

• Venture Lighting International

The lighting divisions of some of these companies also manufacture other products, such as 

fluorescent lamps and ballasts, light emitting diodes (LEDs), other HID lamp technologies, and 

compact fluorescent lamps (CFLs).

3.2.2.1 Small Businesses

Small businesses may be particularly affected by the promulgation of minimum energy 

conservation standards for metal halide lamp fixtures. The Small Business Administration (SBA) 

lists small business size standards that are matched to industries as they are described in the 

North American Industry Classification System (NAICS). A size standard is the largest that a 

for-profit concern can be and still qualify as a small business for Federal Government programs. 

These size standards are generally the average annual receipts or the average employment of a 

firm. For metal halide lamp fixtures the size standard is matched to NAICS code 335122, 

Commercial, Industrial, and Institutional Electric Lighting Fixture Manufacturing, which has a 

size standard of 500 employees or fewer.3 For metal halide lamp ballasts, the size standard is 

matched to NAICS code 335311, Power, Distribution, & Specialty Transformer Manufacturing, 

which has a size standard of 750 employees or fewer.4
3-7

DOE will study the potential impacts on these small businesses in detail during the 

manufacturer impact analysis, which it will conduct as part of the notice of proposed rulemaking 

(NOPR).

3.2.3 Regulatory Programs

Several Federal and international regulatory programs affect the markets for metal halide 

lamp fixtures and ballasts. The following section summarizes U.S. and Canadian regulatory 

initiatives relevant to the fixtures and ballasts covered by this rulemaking. While the following 

discussion is not exhaustive in describing all regulatory action related to metal halide lamp 

fixtures and ballasts, it provides detail on some notable initiatives that characterize recent 

developments in the lighting market.

3.2.3.1 Federal Energy Conservation Standards

Title III of EPCA of 1975, Pub. L. 94-163, (42 United States Code (U.S.C.) 6291 et seq.) 

established an energy conservation program for major household appliances and industrial and 

commercial equipment. More specifically, Part A of Title III (42 U.S.C. 6291-6309) establishes 

the “Energy Conservation Program for Consumer Products Other Than Automobiles.” 

Subsequent amendments to EPCA have given DOE the authority to regulate the energy 

efficiency of several additional kinds of equipment, including certain metal halide lamp fixtures.

On December 19, 2007, the President signed the Energy Independence and Security Act 

of 2007 (EISA 2007) (Pub. L. 110-140), which made numerous amendments to EPCA and 

directed DOE to undertake several new rulemakings for appliance energy conservation standards 

including two cycles for metal halide lamp fixtures. DOE is initiating its first rulemaking cycle to 

review and consider amendments to the energy conservation standards in effect for metal halide 

lamp fixtures, as required under 42 U.S.C. 6295(hh)(2), which provides as follows:

(2) Final rule by January 1, 2012. —

(A) In general. —

Not later than January 1, 2012, the Secretary shall publish a final rule to 

determine whether the standards established under paragraph (1) should be 

amended.

(B) Administration. —

The final rule shall—

(i) contain any amended standard; and

(ii) apply to products manufactured on or after January 1, 2015.

As amended by EISA 2007, EPCA regulates metal halide lamp fixtures designed to be 

operated with lamps rated greater than or equal to 150 watts (W) but less than or equal to 500 W 

by prescribing performance requirements for the metal halide lamp ballasts used in those metal 

halide lamp fixtures. Both metal halide lamps and ballasts are energy-consuming components of 

metal halide fixtures. For this 150 to 500 W metal halide lamp wattage range, metal halide lamp 

fixtures must contain:

(i) a pulse-start metal halide ballast with a minimum ballast efficiency of 88%;
3-8

(ii) a magnetic probe-start ballast with a minimum ballast efficiency of 94%; or

(iii) a nonpulse-start electronic ballast with—

(I) a minimum ballast efficiency of 92% for wattages greater than 250 W; and

(II) a minimum ballast efficiency of 90% for wattages less than or equal to 250

W.

(U.S.C. § 6292 (hh)(1)(A)) 

In addition to prescribing minimum efficiency requirements for the previously-described 

metal halide lamp ballasts contained in metal halide lamp fixtures, EISA 2007 amended EPCA to 

exclude the following types of metal halide lamp fixtures from the statutorily-prescribed energy 

conservation standards:

(i) fixtures with regulated lag ballasts;

(ii) fixtures that use electronic ballasts that operate at 480 volts; or

(iii) fixtures that—

(I) are rated only for 150 watt lamps;

(II) are rated for use in wet locations, as specified by the National Electrical Code 

2002, section 410.4(A); and

(III) contain a ballast that is rated to operate at ambient air temperatures above 50° 

C, as specified by UL [Underwriters Laboratories] 1029–2001 [“Standard for 

High-Intensity-Discharge Lamp Ballasts”].

(42 U.S.C. § 6292 (hh)(1)(B))

Pursuant to section 310 of EISA 2007, EPCA further directs DOE to incorporate standby 

mode and off mode energy use in any amended (or new) standard adopted after July 1, 2010. (42 

U.S.C. § 6295(gg)(3)) Because this energy conservation standards rulemaking must be 

completed by January 1, 2012, the requirement to incorporate standby mode and off mode 

energy use into the energy conservation standards analysis is applicable.

DOE published a final rule test procedure to comply with provisions from EISA 2007 

that apply to metal halide lamp ballasts included in metal halide lamp fixtures that are covered by 

this rulemaking. DOE found that while it is possible for metal halide ballasts to operate in active 

mode and standby mode, the off mode condition does not apply because it addresses a mode of 

energy use in which metal halide ballasts do not operate. 75 FR 10950, 10954-5 (March 9, 2010).

One example of a metal halide ballast that operates in standby mode is a DALIb

Pursuant to EPCA section 325(gg)(2)(A), 42 U.S.C. § 6295(gg)(2)(A), DOE is evaluating 

whether to incorporate standby mode into a single amended or new metric. DOE is also 

-enabled ballast. 

DALI-enabled ballasts exhibit standby power because they have internal circuitry that is integral 

to the design of the ballast that remains on and active, even when the ballast is not driving any 

lamps. 

 b DALI stands for Digital Addressable Lighting Interface, which is a system that enables communication between a 

central lighting controls system and the individual components, including the ballasts.
3-9

evaluating whether to include standby mode standards in this rulemaking. For more information, 

see chapter 2 of the preliminary TSD.

3.2.3.2 California Energy Commission

Prior to the enactment of EISA 2007, the California Energy Commission (CEC) adopted 

regulations for metal halide fixtures that took effect on January 1, 2006. California’s metal halide 

fixture energy conservation standards were amended in August 2009 with the adoption of CEC 

2009 Appliance Efficiency Regulation. According to section 1605.3(n) of California Title 20, 

effective January 1, 2010, metal halide lamp fixtures manufactured and sold in the state of 

California may not be sold with probe-start ballasts, and in addition, must meet at least one of 

following requirements:

1) a) contain ballasts with minimum ballast efficiency of 90% for fixtures designed to 

operate lamps rated 150-250 W, b) contain ballasts with minimum ballast efficiency of 

92% for fixtures designed to operate lamps rated 251-500 W; or

2) contain ballasts with minimum ballast efficiency of 88% and an occupant sensor which 

is an integral control, shipped with the factory default setting to automatically reduce 

lamp power through dimming by a minimum of 40% within 30 minutes or less after the 

area has been vacated; or

3) contain ballasts with minimum ballast efficiency of 88% and have an automatic 

daylight control which is an integral control, shipped with the factory default setting to 

automatically reduce lamp power through dimming by a minimum of 40%; or

4) contain ballasts with minimum ballast efficiency of 88% and a re-lamping rated 

wattage within one of the four wattage bins specified in the following subsections (a) 

through (d). The metal halide lamp fixture shall be able to operate lamps within only one 

of the four wattage bins and shall not be rated for any lamp wattage outside of that 

wattage bin. The metal halide lamp fixture shall have a permanent, pre-printed factoryinstalled label that states the re-lamping rated wattage.

a) 150-160 W; or

b) 200-215 W; or

c) 290-335 W; or

d) 336-500 W, provided that when a metal halide lamp fixture is able to operate 

336 to 500 W lamps, the fixture shall be prepackaged and sold together with at 

least one lamp per socket, having a minimum lamp mean efficacy of 80 lumens 

per watt (lm/W) based on published mean lumens and rated lamp power (in 

watts).

3.2.3.3 Canadian Energy Efficiency Standards

The Natural Resources Canada (NRCan) Office of Energy Efficiency regulates energy 

efficiency of several consumer and industrial products in Canada. In May 10, 2010, NRCan 

published a bulletin on developing standards stating NRCan’s proposal to amend Canada’s 
3-10

Energy Efficiency Regulations to include metal halide lamp ballasts. Table 3.2.1 shows the 

proposed Canadian standards for metal halide lamp ballasts. 

Table 3.2.1 Proposed Canadian Standards for Metal Halide Lamp Ballasts

Ballast Type Lamp Rated Wattage Minimum Rated 

Ballast Efficiency (%)

Magnetic Probe Start 150-500 94

Pulse Start 150-500 88

Non Pulse Start 

Electronic

150-250 90

251-500 92

NRCan proposed that listed standards apply to equipment manufactured on or after July 

14, 2012.

3.2.4 Non-Regulatory Initiatives

DOE reviewed several national, regional, and local voluntary programs that promote the 

use of energy efficient lighting in the United States. These include the Federal Energy 

Management Program’s (FEMP’s) program for energy efficient lighting, the ENERGY STAR 

Program, and the Northeast Energy Efficiency Partnership (NEEP). The following section 

summarizes some of these programs for metal halide fixtures and the ballasts contained in the 

fixtures covered by this rulemaking. While it is not an exhaustive list, the discussion provides 

detail on some notable initiatives that characterize recent developments in the lighting market.

3.2.4.1 Federal Energy Management Program

FEMP helps Federal buyers identify and purchase energy efficient equipment including 

certain metal halide lamp fixtures. Section 161 of EPACT 1992 encourages energy efficient 

Federal procurement. Section 104 of EPACT 2005 requires that each agency incorporate energy 

efficiency criteria consistent with ENERGY STAR and FEMP-designated products for “...all 

procurements involving energy consuming products and systems, including guides 

specifications, project specifications, and construction, renovation, and service contracts that 

include provision of energy consuming products and systems, and into the factors for the 

evaluation of offers received for the procurement.” Executive Order 13123 and Federal 

Acquisition Regulation (FAR) section 23.704 direct agencies to purchase products in the upper 

25% of energy efficiency, including all models that qualify for the ENERGY STAR product 

labeling program. 64 FR 30851, 30854 (June 8, 1999). FEMP provides recommendations for 

how to buy energy efficient industrial luminaires, including the metal halide lamp fixtures shown 

in Table 3.2.2.

5 FEMP offers buyers support tools such as efficiency guidelines, costeffectiveness examples, and a cost calculator. FEMP also offers training, on-site audits, 

demonstrations, and design assistance.
3-11

Table 3.2.2 Federal Energy Management Program Efficiency Recommendation

Upward 

Efficiency* Lamp Wattage

Required Luminaire Efficacy Rating (LER)

Lensed Fixture Open Fixture

0%

150 - 399 50 or higher 49 or higher

400 - 999 62 or higher 69 or higher

≥1000 84 or higher 76 or higher

1% - 10%

150 - 399 68 or higher 49 or higher

400 - 999 73 or higher 75 or higher

≥1000 71 or higher 96 or higher

11% - 20%

150 - 399 70 or higher 55 or higher

400 - 999 76 or higher 81 or higher

≥1000 82 or higher 87 or higher

*Upward Efficiency is the portion of light directed up by the fixture. Both high bay and low bay HID luminaires are 

available with opaque reflectors, which direct all or most of the light downward, and with transparent refractors, 

which direct some light up. 

3.2.4.2 ENERGY STAR

ENERGY STAR is a joint program of DOE and the EPA designed to protect the 

environment by promoting energy efficient products and practices.6

3.2.4.3 Northeast Energy Efficiency Partnerships

Although ENERGY STAR 

does not have specified criteria for HID fixtures, there are criteria for solid state lighting (SSL)

(e.g., LED) outdoor fixtures. These fixtures are direct competitors of HID outdoor fixtures and 

include outdoor pole-mounted area and roadway luminaires, outdoor wall-mounted area 

luminaires (“wall packs”), and parking garage/canopy luminaires. SSL outdoor luminaires that 

qualify for the ENERGY STAR label must meet performance requirements related to light 

output, minimum fitted target efficacy (FTE), maximum luminous flux in glare and uplight 

zones, among other requirements.

NEEP is a regional nonprofit organization that promotes energy efficiency in the 

Northeast. NEEP runs a Commercial Buildings and Technologies Initiative that “focus[es] on 

improved efficiency and energy performance that address the integration of technologies and 

best practices in building systems such as lighting system design.”7 NEEP coordinates with 

multiple local and state governments, utilities, and other initiatives, such as Efficiency Vermont

and the Long Island Power Authority, to promote efficient lighting products.8, 9

3.2.5 Alternative Fixture Efficiency Metrics

Although metal halide lamp fixtures minimum performance requirements are measured by 

the ballast efficiency of the ballast included in the fixture, DOE and the fixture industry has 

researched alternative metrics for fixture efficiency. For the SSL ENERGY STAR Program, 

DOE has developed the FTE metric. NEMA, along with its luminaire division, has developed the 

Target Efficacy Rating (TER). DOE found that in general, overall fixture energy use depends on 

four areas of importance including: lamp efficacy, ballast efficiency, light absorption by the 

fixture, and usefulness of light emitted by the fixture (direction or light distribution pattern). FTE 

and TER metrics treat each area of importance more effectively in some ways than others. The 
3-12

following sections describe each metric and explain how they account for the four areas of 

importance.

3.2.5.1 Fitted Target Efficacy

DOE previously developed FTEc

FTE = (flux in uniform pool ) x (percentage of rectangular target covered by uniform pool)

metric to quantify outdoor pole-mounted luminaire 

performance for ENERGY STAR qualification purposes. In the FTE approach, luminaire 

performance is measured by fitting a rectangle to the uniform “pool” of light specific to each 

luminaire, multiplying the luminous flux (in lumens) landing in this pool by the percent coverage 

of the rectangular target, and then dividing by input power (in watts) to the luminaire. The 

equation can be summarized as:

(luminaire input power)

The resulting calculation is measured against Illuminating Engineering Society (IES)

recommended uniformity ratios. FTE addresses the four areas of importance as follows:

• Lamp Efficacy: FTE takes into consideration lamp efficacy by evaluating light delivered 

to the target. A source has to have a reasonably high efficacy to score a high FTE value.

• Ballast Efficiency: FTE incorporates ballast efficiency by incorporating total wattage of 

the luminaire that is dependent on the ballast input watts. The more efficient the ballast, 

the closer to the lamp wattage the total wattage of the luminaire will be.

• Light Absorption: FTE takes into account absorption of light by the fixture by evaluating 

light delivered to the target. A less efficient optical system yields a lower FTE value.

• Light Distribution: FTE only accounts for light hitting a specific target (rectangle) and 

does not take into account other surfaces where light is desired and the luminaire is 

design to light.

Through using uniformity and rectangularity of distribution as the criteria for useful 

luminous flux, the same method of calculation can be applied to luminaires of all IES types 

(Types I through V), and no project-specific geometries or criteria are required. However, FTE 

only accounts for light hitting the specified target area and does not take into account other 

surfaces where the luminaire is designed to light. ENERGY STAR has not yet adopted FTE for 

outdoor lighting and NEMA is working with EPA to develop a possible alternative to FTE.

3.2.5.2 Target Efficacy Rating

TER d

 c The DOE introduction to FTE is available here: http://www.illinoislighting.org/resources/FTEoverview01Jul09.pdf

metric was developed by NEMA’s luminaire division to succeed the previous 

metric of Luminaire Efficacy Rating (LER). TER calculates fixture efficacy by multiplying the 

d NEMA issued a revised version of the Target Efficacy Rating metric in 2009, LE 6-2009, available here: 

http://www.nema.org
3-13

light leaving the luminaire by a value (Coefficient of Utilization) that factors in the distribution 

of light. Coefficient of Utilization (CU) calculates the percentage of rated lamp lumens reaching 

a fixture specific target. TER is calculated as follows:

TER = EEF x TLL x BF / Input Watts

Where:

TER = Target Efficacy Rating, expressed in rated lumens per watt,

EEF = Energy Effectiveness Factor, the percentage of lumens that fall upon a specified typical 

target area for a luminaire. The method for calculating EEF is a function of luminaire 

type,

TLL = Total initial lamp lumens, total number of lamps in the test luminaire multiplied by the

published rated initial lamp lumens,

BF = Ballast factor of test ballast or the average ballast factor of test ballasts used in the 

photometric test, and

INPUT WATTS = Total wattage of the luminaire as measured during the photometric test, or 

calculated based on the ballast manufacturers’ published data for that lamp/ballast 

combination if photometric test data is not available.

TER addresses the four areas of importance as follows:

• Lamp Efficacy: TER indirectly considers lamp efficacy by accounting for lumen output 

from the lamp. Lumen output for the lamp component is based on manufacturer 

published data only. 

• Ballast Efficiency: TER incorporates ballast efficiency by using the total wattage of the 

luminaire that is dependent on the ballast input watts. The more efficient the ballast, the 

closer to the lamp wattage the total wattage of the luminaire will be.

• Light Absorption: TER accounts for thermal and optical losses by evaluating the portion 

of rated lamp lumens delivered to the workplane.

• Light Distribution: TER builds upon LER. LER previously only looked how much light 

left the luminaire versus in the input power. TER factors in the light distribution via CU. 

The light reaching the target is most important for a fixture. TER has different targets 

defined for different fixture types. 

TER takes luminaire general applications into consideration, allowing for different 

classifications (e.g., indoor and exterior, subdivided into specific applications with both groups).

However, TER has many different values for the different luminaires. Each luminaire type has a 

different TER calculation method and value. Even though fixtures will generally fall within one 

of the different classifications for TER purposes, there are certain fixtures that can fall within 

multiple categories of luminaire due to their designs. TER has been incorporated into some 

pending outdoor lighting legislation currently in congressional review.
3-14

3.2.6 Historical Shipments

Awareness of annual equipment shipment trends is an important aspect of the market 

assessment and the development of the standards rulemaking. For this rulemaking, DOE used 

publicly available HID lamp fixture shipments from the U.S. Census from 1993 to 200110, lamp 

shipment data from the HID determinatione

DOE used this data for three main purposes. First, the shipment data and market trend 

information contributed to the shipments analysis and base-case forecast for metal halide fixtures 

(chapter 9 of the preliminary TSD). By using historical shipment data and expert opinion on 

market trends and calibrating forecast assumptions with recent data, DOE believes it has based 

the shipments model and base-case forecasts on a sound dataset. Second, DOE used the data to 

select the representative product classes and representative units for analysis (chapter 5 of the 

preliminary TSD). Third, DOE used the data to develop the installed stock of fixtures for the 

national impact analysis (chapter 10 of the preliminary TSD). Based on its understanding of 

trends in the market, DOE estimated how the market would respond to various candidate 

standard levels.

, confidential lamp shipments from 2002 to 2008 

from NEMA, and market trend information from manufacturers to develop historical shipment 

for metal halide lamp fixtures from 1993 to 2009.

3.2.6.1 HID Lamp Fixtures Shipments

The U.S. Census historical shipment data for HID lamp fixtures is broken down into 

market sectors including commercial and institutional, industrial, and outdoor lighting. Within 

each market sector, the shipments are categorized by a variety of applications. Different 

applications under the commercial and institutional sector include surface or pendant, indirect 

lighting, recessed insulation contact (IC), and recessed non-IC. Under industrial, shipments are 

broken into applications including general lighting and hazardous lighting. For outdoor lighting, 

shipments are broken into street and highway lighting, general purpose floodlighting, HID sports

lighting, and HID area and site lighting. Although the Census data includes metal halide lamp 

fixtures in the figures, it does not separate metal halide lamp fixtures from other sources such as 

high pressure sodium (HPS) or mercury vapor (MV) lamps. 

Figure 3.2.1 depicts the HID lamp fixture market based on shipments reported to the U.S. 

Census in 2001.

 e A final determination concerning the potential for energy conservation standards for HID Lamps was published in 

the Federal register on July 1, 2010. 75 FR 37975, The document in its entirety can be found at: 

http://www1.eere.energy.gov/buildings/appliance_standards/commercial/high_intensity_discharge_lamps.html
3-15

Figure 3.2.1 2001 HID Fixtures Market Share by Segment

Table 3.2.3 shows all of the HID lamp fixture shipments from the U.S. Census from 1993

to 2001.

Commercial 

and 

Institutional 

Type

10%

Industrial 

Type

34%

Outdoor 

Lighting

56%
3-16

Table 3.2.3 U.S. Census Shipments of HID Lamp Fixtures from 1993 to 2001

HID Fixtures Market Segments Shipments by Year (value in thousands)

1993 1994 1995 1996 1997 1998 1999 2000 2001

Electric Lighting 

fixtures, 

commercial and 

institutional type 

(except portable 

and spotlight)

HID

surface or pendant 191 167 128 163 - - - - -

indirect lighting 81 88 53 43 281 214 246 274 289

recessed non-IC (3-inch 

minimum clearance 

from ceiling insulation)

open reflector 464 370 586 576 342 337 725 758 509

enclosed 337 335 201 188 141 110 201 226 203

recessed IC (direct 

contact with ceiling 

insulation)

open reflector - - - - - - - - -

enclosed 20 15 13 8 7 3 16 27 33

Electric lighting 

fixtures, industrial 

type

General lighting 

(except portable)

HID including 

integrally mounted and 

remote ballasts

open reflector 928 1495 1691 1755 2319 2095 1878 2277 1879

enclosed 900 902 1095 1240 1724 1587 1403 1531 1374

parking garage lighting 

(fixtures designed 

specifically for this 

application)

104 136 120 111 151 123 149 360 247

Outdoor lighting 

equipment, 

excluding lamps

Street and highway 

lighting 

luminaries, 

including bridge 

and tunnel lighting

HID types, including 

low pressure sodium 

and integrally mounted

and remote ballasts

open 503 528 476 546 605 613 2721 561 565

enclosed 1266 1286 1361 1229 1382 805 1308 1376 1229

Floodlighting, 

area, and site 

lighting luminaires

General-purpose 

floodlighting

HID types, general, including 

low pressure sodium and 

integrally mounted and 

remote ballasts

1028 1103 1184 1363 1596 1371 1475 1390 1326

HID sportslighting (fixtures designed specifically for 

this application) 148 160 174 181 231 251 267 252 252

HID area and site 

lighting

site lighting (under 20-foot 

mounting) 1786 1935 1285 2668 2103 2131 1350 1452 1477

bollards 33 39 50 58 81 80 94 97 97

post-top 99 100 135 128 145 143 144 137 142

large area lighting (20- to 60-

foot mounting) 470 482 453 761 829 755 829 828 794

Totals 8,358 9,141 9,005 11,018 11,937 10,618 12,806 11,546 10,416
3-17

3.2.6.2 Estimated Historical Metal Halide Lamp Fixtures Shipments

To develop metal halide lamp fixture historical shipments from 1993 to 2001, DOE used 

the U.S. Census HID lamp fixture shipments and lamp shipments by type used in the HID 

determination. For each year, DOE received information on total metal halide lamps shipped and 

compared with total HID lamp shipments. DOE then applied the same percentage of metal halide 

lamps to the U.S. Census HID lamp fixture data to estimate total metal halide lamp fixtures 

shipments from 1993 to 2001. The percentages and methodology is discussed in more detail in 

Chapter 9 of the preliminary TSD. Table 3.2.2 shows the estimated historical shipments for 

metal halide lamp fixtures from 1993 to 2001.

Table 3.2.1 Estimated Historical Shipments of Metal Halide Lamp Fixtures from 1993 to 

2001

Year Estimated Total Metal Halide 

Lamp Fixture Shipments*

1993 2,701,000

1994 3,219,000

1995 3,885,000

1996 4,292,000

1997 4,884,000

1998 5,698,000

1999 6,697,000

2000 6,697,000

2001 6,771,000

* Shipments rounded to the nearest thousand

DOE’s estimates show that from 1993 to 2001 metal halide lamp fixtures shipments have 

approximately doubled. In terms of growth, the market showed an average of 10% per year 

between 1993 and 2001. In comparison HPS fixtures, a possible alternative to metal halide in 

certain applications, had an average market loss of 7% per year for the same time frame.

For 2002 to 2009, because U.S. Census data is not available for HID lamp fixtures, DOE 

used confidential lamp shipment information and estimated market shares of metal halide 

fixtures to estimate total metal halide lamp fixtures shipments per year. The estimated market 

shares of metal halide lamp fixtures is based on the historical U.S. Census data from previous 

years. Table 3.2.2 shows the estimated historical shipments for metal halide lamp fixtures from 

2002 to 2009.

Table 3.2.2 Estimated Historical Shipments of Metal Halide Lamp Fixtures from 2002 to 

2009

Year Estimated Total Metal Halide 

Lamp Fixture Shipments*

2002 6,956,000

2003 7,102,000

2004 7,362,000

2005 7,866,000

2006 8,108,000

2007 8,157,000

2008 7,552,000

2009 7,741,000
3-18

* Shipments rounded to the nearest thousand

In terms of growth, the market showed an average of 1.54 percent growth per year between 2002 

and 2009. Due to overall market downturn, which was also expressed by manufacturers during 

interviews, DOE estimates shipments significantly decreased in 2008. Also, manufacturers in 

general estimate that alternative technologies such as fluorescent lamps and LEDs have captured

significant market share. Fluorescent technology has improved and its lower cost has attracted 

consumers. Additionally, LED fixture costs have significantly decreased due to competition in 

the market along with increase in consumers’ request for low maintenance and more efficacious 

technologies. In general, manufacturers predict that HID applications will eventually be 

overtaken by LEDs but will have to go through a transitional period. For a complete explanation 

on how DOE estimated historical shipments and additional information on shipments, see 

chapter 9 of the preliminary TSD.

3.3 TECHNOLOGY ASSESSMENT

The purpose of the technology assessment is to develop a preliminary list of technologies 

that could be used to improve the efficiency of metal halide lamp ballasts that are incorporated in 

metal halide lamp fixtures. The following assessment provides a description of the basic 

construction and operation of metal halide fixtures, lamps, and ballasts, followed by technology 

options to improve efficiency of metal halide ballasts.

3.3.1 Metal Halide Lamp Fixtures Overview

Since the inception of metal halide lamps in the lighting market in the late 1960’s, metal 

halide lamp fixtures have evolved from a few industrial applications to a vast array of uses such 

as residential applications, commercial retail, sports lighting, warehouses, hangars, airports, 

libraries, natatoriums, and several other industrial applications. Technology advances in both 

lamps and ballasts have significantly increased the energy efficiency of metal halide lamp 

fixtures. Also, manufacturers have made optional fixture components available, such as daylight 

sensors or occupancy sensors, which add both functionality and overall energy savings for the 

end user.

3.3.1.1 Basic Metal Halide Lamp Fixture Structure

The basic metal halide lamp fixture is comprised of a lamp, ballast, ballast housing or 

structure, optics, and wiring. Ballast housings are typically made of plastic, aluminum, or 

different types of steel. There is a variety of optics used, which are typically made of glass, 

acrylic, aluminum, or sheet metal. The shape and reflectivity of the optics are key factors in 

determining how effective the fixture distributes light to the desired target. Fixtures are 

commonly sold with lamps and ballasts. Manufacturers also offer additional components as 

options depending on the application. Table 3.3.1 shows the basic structure of a typical metal 

halide lamp fixture. 
3-19

Enterprise 22, Source: Cooper Lighting - Lumark

Figure 3.3.1 Metal Halide Lamp Fixture Structure

Fixtures generally fall within two basic categories: indoor and outdoor. The following 

section discusses types of luminaires within each category. While it is not an exhaustive list, the 

discussion provides detail on different fixtures that are common within each category. Also 

discussed are additional options manufacturers offer in fixtures that reduce overall energy 

consumptions.

3.3.1.2 Indoor Fixtures

Downlight

Downlights are fixtures with light distribution directed downward onto a horizontal 

plane. Downlights usually incorporate a tight optical cut-off of 45° to 50°.11 These fixtures may 

be recessed or surface-mounted. Construction includes aluminum or similar metal structure with 

optics, wiring, and either ballast housing or remote ballast. Typical applications include shopping 

mall or clothing stores, museums, or residential where lighting fixture is recessed into a lower 

ceiling. Typical power ratings are 70 or 100 W. Similar to high- and low bay fixtures, the ballast 

housing is more modular and an increase in ballast size would not likely require an entirely new 

fixture.
3-20

Lithonia LP6HN Open PAR, Source: Lithonia Lighting

Figure 3.3.2 Example of Recessed Downlight Metal Halide Lamp Fixture

High Bay

High bays provide general illumination to an area where the floor-to-ceiling height is 

greater than 25 feet. Most common construction includes aluminum or plastic ballast housing 

with wiring near the mounting location and optics attached below the ballast housing. An 

increase in ballast size might require a larger ballast housing (shown as the white box near the 

top of Figure 3.3.3), but would be unlikely to affect the optical portion of the fixture. The 

luminaire is generally hung via chain or hook rather than mounted. Typical applications include 

hangars, retail stores or warehouses, or industrial applications with high ceilings. Manufacturers 

offer different ballast options including both magnetic and electronic type. Wattage range varies 

from typical 250 W up to 1000 W. 

Lithonia TPG High Bay, Source: Lithonia Lighting

Figure 3.3.3 Example of High Bay Metal Halide Lamp Fixture

Low Bay

In contrast to high bay, low bay luminaires provide general illumination to an area where 

the floor-to-ceiling height is less than 25 feet. Most common construction includes aluminum or 

plastic ballast housing with wiring near the mounting location and optics attached below the 

ballast housing. Because the wattage range is less than high bay, there is less thermal protection 
3-21

from the lamps to other components of the fixture. The luminaire is generally hung via chain or 

hook rather than mounted. Typical applications include retail stores or warehouses, some parking 

garages, or industrial applications with low ceilings. Manufacturers offer different ballast options 

including both magnetic and electronic type. Wattage range varies from 70 W up to 400 W.

Lithonia SX PA25D Low Bay; Source: Lithonia Lighting

Figure 3.3.4 Example of Low Bay Metal Halide Lamp Fixture

Uplight

In opposition to downlight, an uplight fixture has a light distribution directed upward 

onto a horizontal plane or vertical surface. Uplights usually incorporate a tight optical cut-off of 

45° to 50°.12

3.3.1.3 Outdoor Fixtures

These fixtures may be recessed or surface-mounted. Construction includes 

aluminum or similar metal structure with optics, wiring, and either ballast housing or remote 

ballast. Typical applications include airports, double height spaces, museums, and natatoriums. 

Wattage range varies from as low as 70 W up to 1000 W.

Area/Roadway (Streetlight)

Area/roadway fixtures designed to produce reasonably uniform illuminance on streets, 

roadways, and or parking areas. Most common construction includes wiring, optics and ballasts 

enclosed by an aluminum or steel housing. These fixtures are generally mounted on poles or 

vertical surfaces such as building walls. With improvements of weatherization and electrical 

design, manufacturers are beginning to offer ballast options, including electronic ballasts, beyond 

the common coil and core magnetic ballasts. Common wattage range varies from 70 W up to 400 

W.
3-22

Lithonia KSE, Source: Lithonia Lighting

Figure 3.3.5 Example of Area/Roadway Metal Halide Lamp Fixture

Bollard

Bollard fixtures designed to be installed along pathways and in front of buildings. 

Bollards can be simple pathway post lights as well as robust posts used to provide a barrier and 

to keep vehicles from leaving roadways. Construction can be aluminum, steel or even concrete

for stronger applications. Optics are usually mounted near the top of the post structure and 

ballasts can be either remote or included in the fixture. Wattage range is commonly limited to 

250 W.

Lithonia KBE, Source: Lithonia Lighting

Figure 3.3.6 Example of Bollard Metal Halide Lamp Fixture

Canopy

Canopy fixtures are designed to be installed under canopy structures. These fixtures may 

be recessed or surface-mounted. Construction includes aluminum or similar metal structure with 

acrylic optics, wiring, and ballast housing. Canopy fixtures are most commonly installed in gas 

stations and garages. Typical power ratings are 150 W or 250 W.
3-23

Lithonia KACM, Source: Lithonia Lighting

Figure 3.3.7 Example of Canopy Metal Halide Lamp Fixture

Cobrahead

Similar to area/roadway fixtures, cobraheads are designed to produce reasonably uniform 

illuminance on streets and roadways. These fixtures have been available in the market for more 

than 50 years but have gone through several changes, including the addition of metal halide 

technology and, most recently, LED. Mounting is usually done on a curbside pole, with an arm 

extending out over the roadway and the fixture at its end. Robust construction includes 

aluminum or similar metal structure with acrylic drop-bowl optics, wiring, and easily accessible

ballast housing. Cobraheads are only used in roadways and street lighting applications. Wattage 

is commonly found in the 250 W range, but can be as high as 400 W.

Lithonia CHL, Source: Lithonia Lighting

Figure 3.3.8 Example of Cobrahead Metal Halide Lamp Fixture

Floodlight

Floodlights are multi-purpose fixtures designed to supplement other lighting or to provide 

illuminance to a wide area. Construction includes aluminum or similar metal structure with 

acrylic or glass optics, wiring, and either ballast housing or remote ballast. Yoke-mounted 

fixtures used to supplement area/parking lot luminaires. These fixtures are generally yokemounted on building surfaces or on the ground. Typical applications include parking lots, 
3-24

recreation areas, building facades, monuments, airports and docks. Wattage range varies from as 

low as 70 W up to 1000 W.

Lithonia TFL, Source: Lithonia Lighting

Figure 3.3.9 Example of Floodlight Metal Halide Lamp Fixture

Parking Garage

Parking Garage fixtures are designed to light ramps and parking areas of parking 

structures. Construction includes aluminum or similar metal structure with acrylic or glass optics, 

wiring, and ballast housing. These fixtures can be surface-mounted or slightly suspended. Due to 

parking structures’ typical ceilings heights of less than 12 feet, these luminaires are limited to 

lamps rated at or less than 500 W.

Lithonia PGR, Source: Lithonia Lighting

Figure 3.3.10 Example of Parking Garage Metal Halide Lamp Fixture

Post-Top

Post-top fixtures are designed to be mounted directly on top of light posts and to provide 

general lighting. Unlike other fixtures that typically hang from ceilings or are installed on arms 

protruding from poles, post-top fixtures are installed directly on top of poles. Construction 

includes aluminum, sheet metal, or similar metal structure with acrylic or glass optics, wiring, 
3-25

and ballast housing. These fixtures have been associated with Dark Skies initiativesf

noncompliant fixtures because of their inherently poor fixture efficiency. Typical applications 

include street sidewalks, and parks.

Lithonia TCL, Source: Lithonia Lighting

Figure 3.3.11 Example of Post-Top Metal Halide Lamp Fixture

Sports Lighting

Sports lighting fixtures are designed to provide necessary lighting for sporting venues. 

For light-weight construction, these fixtures are made of either aluminum or light-weight sheet 

metal with acrylic optics. They include wiring and are typically remote ballasted. Because of the 

application, these fixtures are typically mounted in groups of 20 or more fixtures for maximum 

area coverage and light intensity. Additionally, because of the significant mounting heights and 

necessary light intensity, wattage is typically in the 1000 W range or higher.

Lithonia TSP, Source: Lithonia Lighting

Figure 3.3.12 Example of Sports Lighting Metal Halide Lamp Fixture

Wallpack

 f Initiatives following the The International Dark-Sky Association’s (IDA) movement to limit light pollution.
3-26

Wallpack fixtures are designed to be a self-contained fixture mounted to vertical wall 

surfaces. Construction includes aluminum, sheet metal, or similar metal structure with acrylic or 

glass optics, wiring, and ballast housing. With inherently poor fixture efficiency, wallpacks 

direct light downwards but most of the time end up spraying light out as glare. Typical 

applications include building walls lining parking lots, parking structures, or any other outdoor 

building walls were directional lighting is not necessary. Typical power rating is 150 W.

Lithonia TWP Wall Pack, Source Lithonia Lighting

Figure 3.3.13 Example of Wallpack Metal Halide Lamp Fixture

3.3.1.4 Energy Related Fixture Options

Lighting Controls

Generally, light sources are equipped with lighting controls for aesthetic or energy 

management control in addition to ASHRAE/IESNA 90.1 and other energy code compliance. 

Metal halide fixture lighting control technologies to conserve energy include: switching devices, 

timing and sensing devices, and dimming controllers.

Switching Devices: Switching decreases energy consumption by limiting the number of

operating hours to only the times when light is needed. Although increasing switching frequency 

increases re-lamping costs, the energy savings associated with decreasing operation hours 

outweighs the new fixture costs. Electric Power Research Institute (EPRI) Controls Pattern 

Book analyzed the trade-offs between increased costs and amount of energy saved, and 

concluded that energy cost reductions surpasses the costs of re-lamping by 6 to more than 20 

times.g

Because metal halide lamps have extended warm-up periods and can take up to several 

minutes to restrike after having been extinguished, two-level systems (also called bi-level, 

stepped, or hi-lo systems) are used so that the lamp remains warm, ensuring quick transition 

from low to full light. Bi-level switching can lead up to 10% energy savings in retail 

applications. Specific luminaires with two-lamp tandem wired ballasts and circuit switch legs, or 

multistep ballasts are capable of multilevel lighting controls.

Additionally, time delays, discussed later, can be incorporated into the system to 

optimizing the switching schedule. 

13

 g EPRI Controls Pattern Book, Rundquist, McDougal, et al, 1996.

Multistep ballasts are used to step 
3-27

down the lamps in a luminaire, eliminating uneven appearance by reducing lumen output of all 

of the lamps without the need to switch any off. Multilevel ballasts which provide ability to be 

switched between two or more illuminances and provide a low-cost, but limited control approach 

for dimming. Multilevel ballasts that change illuminance in steps, and switching systems in 

general, are most practical in warehouses, parking garages, tunnels, and daylighting applications.

Timing and Sensing Devices: Timing and sensing devices are meant to control lighting in 

response to known or, as previously mentioned, scheduled sequences of events (i.e., to turn off 

lights when they are not needed.) Time delays often work in conjunction with sensing devices to 

determine the interval between the last detected motion and the switching off of the fixtures. 

Some products have fixed settings, while most have adjustable time delay settings. Timing 

devices are also coupled with override functions to accommodate deviations from schedules, and 

may be coupled with microprocessors which can control multiple events and lighting effects.14

Photosensors, a type of sensing device, use electronic components that transform visible 

radiation, or light, into an electrical signal which is then used to control another system or lamp. 

Photosensors are typically used to detect when an outdoor lamp should be turned on and off.15

These sensors are either immune to or filtered from ultraviolet (UV) or infrared (IR) radiation. 

Photosensors are either in an open- or closed-loop system. An open-loop system is one in which 

the photocell responds only to daylight levels, but is still calibrated to the desired light level 

received elsewhere, such as on the floor of the warehouse. Most frequently, open-loop 

photosensors are used in warehouse high rack areas, where the lighting levels must be calibrated 

separately from photosensors in open areas.16

The alternative to photosensors is occupancy, or motion sensors. Occupancy sensors are 

meant to automatically switch off fixtures when spaces are unoccupied, and to switch fixtures on 

when they are occupied or light is needed. Electrical consumption is reduced by cutting the 

number of operating hours. These sensors take advantage of incomplete occupancy loads during 

periods of peak electric use. Occupancy can be sensed by audio, ultrasonic, passive infrared, or 

optical means. Most occupancy sensors used in commercial applications use passive infrared 

(IR) or ultrasonic motion-sensing technologies. Passive IR occupancy sensors respond to the 

movement of IR sources using a pyroelectric detector located behind an IR-transmitting lens. 

Ultrasonic occupancy sensors transmit pressure waves at an inaudible frequency to detect motion 

within the space. Energy savings are earned when the sensitivity of the occupancy sensor and 

time delay are specifically calibrated to operate effectively for an area.

Dimming Controllers: Dimmers are resistors that rapidly shut the electrical circuit in a 

fixture on and off, ultimately reducing the wattage and lumen output of the lamps. Special 

magnetic or electronic dimming ballasts are required for metal halide fixtures. These ballasts can 

be dimmed down to 10 or 20% of the maximum light output. However, unlike fluorescent 

dimming ballasts, metal halide dimming ballasts typically lose significant luminous efficacy after 

the lumen output drops to around 30% of maximum output.h Although the efficacy levels may 

depreciate after significant dimming, commercial dimming still offers significant lifetime 

savings over systems without dimming options. Average energy savings from dimming in typical 

1200 W commercial loads can be up to 20%.17

 h Heschong Mahone Group

Additionally, certain dimming ballasts can be 
3-28

located away from the control panel by transmitting their individually coded identification 

number for special IR remotes or wall box controllers, leading to potential energy savings.

Emergency and Standby Circuitry

There are many regulations covering and defining emergency lighting; these 

specifications include UL standards, national safety requirements (such as The National Fire 

Protection Agency’s Life Safety Code (NFPA 101) Articles 7.8 and 7.9, NFPA 70 (National 

Electrical Code; NEC), and Occupational Safety and Health Administration (OSHA) 

regulations), and building codes (such as UBC, IBC, state, and local codes). While these 

regulations do not contain rules specifically for metal halide lamp fixtures, sometimes a fixture’s 

added emergency lighting utility will be necessary to have its location meet standards. Metal 

halide lamp fixtures have options for emergency lighting, required standby systems, and optional 

standby systems that provide the needed illumination while limiting the use of backup energy.

Emergency Circuit Module: Some metal halide fixtures incorporate an optional 

emergency circuit module (hereafter ECM). The ECM operates and controls an additional lamp 

that is part of the fixture, but not wired to the ballast. This backup lamp, typically incandescent 

or halogen, is wired by a separate circuit to the emergency power source of the application (e.g., 

a building’s backup generator). In the case of a power outage, the ECM turns on the extra lamp 

to provide illumination while using only a minimal amount of power (e.g., backup lamps 

commonly use between 100-250 W).

Auxiliary Lamp Module: Some metal halide lamp fixtures incorporate an optional 

auxiliary lamp module (hereafter ALM) to comply with optional standby lighting system 

regulation. The ALM operates and controls an additional lamp wired through a dedicated 

(usually 120 V) tap from the ballast. This backup lamp, typically incandescent or halogen, 

provides temporary low-level illumination in the event of a momentary power interruption until 

the metal halide lamp restrikes. Additionally, the ALM is activated in case of lamp failure.Metal 

Halide Lamp Ballast Technology Options

3.3.2 Basic Structure of Metal Halide Lamps

A standard metal halide lamp comprises an arc tube, a bulb (or outer jacket), electrical 

connections, and a base. The arc tube, commonly made of quartz or sintered alumina, is the lightproducing portion of the lamp. As in the older MV lamps, the metal halide arc tube is filled with 

a pressurized mixture of mercury vapor and noble gases (commonly argon). Unlike the MV 

lamps, metal halide lamps contain metal halide salts that radiate at different frequencies when 

ionized. The specific elements involved vary by application and type of light desired, and help 

produce a fuller spectrum and better coloring rendering relative to MV lamps.

The arc tube is surrounded by an outer bulb that protects the inner components, provides a 

structure for mounting them, and retains heat and ultraviolet radiation. In lamps rated for use in 

“open fixtures,” the arc tube is surrounded by an additional glass shroud that protects the outer 

jacket in the event of an arc tube explosion. Lamps may be single-ended (e.g., screw-type or 

bayonet-type lamps) or double-ended (i.e., requiring electrical connection at both ends of the 

outer bulb).
3-29

Like other gas discharge lamps, metal halide lamps exhibit negative differential 

resistance. Because their resistance declines with increasing current, they are unable to regulate 

their own current and require ballasts to operate. When cold, however, the gas resistance is 

relatively high and the ballast’s operating voltage is not usually enough to establish an arc. To 

overcome this problem, two primary starting methods are used: probe and pulse.

In a probe-start lamp, there is a third, starting electrode present in the arc tube. The 

starting electrode is closer to the opposite side of the lamp than the operating electrode, and 

requires less voltage to overcome the cold gas’ resistance. Once an arc is struck, a bimetal switch 

heats and removes the starting electrode from the circuit, allowing the operating electrode to take 

over. The addition of a third electrode and moving parts can make probe-start lamps less 

consistent over their lifetimes in color and lumen output than their pulse-start cousins, and the 

industry has begun to move away from probe-start lamps.

In a pulse-start lamp, there are only two electrodes. The pulse-start ballast strikes an arc 

by generating a high-voltage pulse (typically several kilo-Volts (kV)) using a special circuit 

called an “igniter.” This simpler, more reliable lamp comes at the cost of a more complex ballast. 

Some manufacturers advertise a third starting method called resonant start, which uses electronic 

controls to more gradually build up to ignition voltage. DOE’s understanding is that this method 

is closely related to pulse-start, in that both use two electrodes and accomplish their function 

through higher voltage instead of a shortened arc length. In principle, igniters allow pulse-start

and resonant-start lamps to operate at higher fill pressures, which can reduce electrode sputtering 

and extend lamp life.

Arc tubes for both probe-start and pulse-start lamps are typically made of either fused 

quartz or sintered alumina. Quartz tubes typically use a white coating at their ends to reduce 

thermal losses. Alumina arc tubes, often called “ceramic,” are less permeable to certain metal 

halide ions and, consequently, are thought to offer better color stability, color rendering, and 

luminous efficacy. Studies done by manufacturers have shown that it is difficult to operate

ceramic metal halide (CMH) lamps at high frequencies because higher fill pressures tend to 

move destructive resonant modes upwards in the spectrum. Particularly at smaller bulb sizes, the 

frequencies required to avoid those resonant modes are often on the order of a megahertz (MHz), 

frequencies which can produce electromagnetic interference (EMI). All commercially available 

CMH lamps operate at low (sub-resonant) frequencies, between 0 and 400 Hz.

An elliptically shaped outer bulb or envelope, usually made of borosilicate glass, contains 

the arc tube. The bulb protects and buffers the arc tube and internal electrical connections from 

the environment. The outer envelope contains low-pressure inert gas (e.g., nitrogen) or a 

vacuum, which not only helps minimize the oxidation of internal components, but also provides 

a margin of safety against threat of arc tube rupture (also known as non-passive failure). The 

outer envelope also provides additional thermal buffering for a more stable arc temperature. The 

glass itself absorbs the majority of ultraviolet radiation.20

Inside the outer bulb are conductors, to supply the arc tube with electricity, and structural 

metal components, to support it. There might be other, minor components also within the outer 

bulb, including resistors, diodes, and small tabs called “getters” that help absorb impurities. Like 

other HID lamps, metal halide lamps often have bases resistant to corrosion.
3-30

3.3.3 Metal Halide Lamp Ballast Overview

Metal halide lamp ballasts are “devices that, by means of resistance, inductance, 

capacitance, or electronic elements, singly or in combination, control the current, voltage, and 

waveform for proper lamp starting and operation.” (American National Standards Institute 

(ANSI) C82.9-1996). The following sections discuss basic ballast operation of both ballast types: 

electromagnetic (“magnetic”) and electronic.

A ballast has three primary functions:

1. To establish an electric arc through the lamp

2. To limit current through the lamp after ignition

3. To compensate for variations in line voltage and ensure consistent lumen output

Magnetic ballasts were the first technology used to operate lamps; electronic ballasts 

were developed later because of their higher efficiency. Section 3.3.4 provides additional 

discussion on these and other technology options that can be used to increase the efficiency of 

metal halide lamp ballasts.

There are many performance parameters used to describe the operation of a metal halide 

lamp ballast. These include ballast efficiency, starting method, power factor (PF), total harmonic 

distortion (THD), and EMI. These performance parameters are briefly discussed in the following 

sections.

3.3.3.1 Ballast Efficiency

Although the metal halide lamp test procedure requires a reference lamp for the test 

setup, metal halide ballast efficiency is a purely electrical metric and requires no photometric 

measurements. Ballast efficiency is measured in accordance with section 6.0 of ANSI C82.6, and 

equal to the ratio of lamp input power to ballast input power.

3.3.3.2 Starting Method

Metal halide lamp ballasts can be categorized by the manner in which they operate the 

lamp, or more specifically, how the lamp is started. Metal halide lamps require a lower voltage to

start than to operate. Before starting, the non-ionized lamp compounds present a relatively high 

impedance that the ballast must overcome. As the arc is struck, the lamp gases ionize to form a

plasma whose impedance decreases with increasing current. As previously stated, ballasts 

commonly use two different starting methods: probe-start and pulse-start. Starting method can 

affect efficacy, color rendition, restrike time, and lumen depreciation.

Pulse-start lamps, as mentioned in section 3.3.2, have two electrodes that are used to both 

start and operate the lamp. The ballast alone is unable to supply a breakdown voltage, and 

requires a separate component called an “igniter” to provide the arc-establishing voltage pulse. In 

magnetic ballasts, there is an obvious physical distinction between the igniter and the “run” 

section of the ballast; in electronic ballasts the separation is less evident. Furthermore, an igniter 

allows an extinguished lamp to be re-ignited well before the gas has cooled to temperatures at 

which a probe-start ballast could restrike the arc.
3-31

Probe-start ballasts overcome the cold gas’ breakdown voltage through use of a third, 

starting electrode. The starting electrode is longer and allows an arc to be struck with a lower 

voltage. As the lamp runs and heats, a bimetal switch disconnects the starting electrode, and the 

primary, running electrode takes over. Even with the starting electrode, however, probe-start 

lamps cannot be pressurized to the more efficient levels that pulse-start lamps are. The extra 

electrode introduces one more possible source of contamination, affecting lamp life and color 

rendition. EISA 2007 required probe-start ballasts to be 94% efficient, effectively relegating 

them to uncovered wattage ranges.

Resonant starting is exclusive to electronic ballasts. Although some resonant-start ballasts 

are designed to work in conjunction with specific lamps, most operate with ordinary pulse-start 

lamps. While pulse-starting strikes an arc using a high voltage pulse (or pulse train), resonant 

starting delivers alternating current at one of the lamp’s resonant modes, rapidly building voltage 

until gas breakdown occurs. In addition to potentially being gentler on the lamp, resonant starting 

might not require specialized, pulse-creating hardware. Resonant starting has its hazards 

however, especially in hot restrike situations where the gas impedance is higher than usual. The 

arc is more difficult to strike, allowing voltage to build to the point where components of the 

system sustain damage. Resonant starting is less standardized than pulse-start, and can be 

reliably employed only in certain lamp/ballast combinations.

Manufacturers have marketed pulse-starting as an energy-saving technology in metal 

halide lighting. DOE’s current understanding is that the primary advantage to pulse-starting 

comes in increased lamp efficacy, rather than better electrical efficiency in the ballast itself. 

Nonetheless, the ability to operate a more-efficacious pulse-start lamp is a feature that DOE 

believes could result in significant energy savings. As a result, DOE is considering a design 

standard that encourages pulse-starting, discussed in Chapter 5 of the preliminary TSD.

3.3.3.3 Power Factor

Power Factor (PF) is equal to the ratio of the active power to the apparent power. PF 

depends on the current’s wave shape as well as the phase angle between the current and the 

voltage. The power input is measured with a wattmeter capable of indicating the average power 

in watts. The ballast input voltage multiplied by the ballast input current is the ballast’s apparent 

power (ANSI C82.13-2002). 

Ballast Input Voltage Ballast Input Current

Power Input Power Factor

∗ =

Equation 3.1

Where: 

PowerFactor = power factor, 

PowerInput = input power in watts to ballast, 

BallastInputVoltage = input voltage in volts to ballast, and 

BallastInputCurrent = input current in amps to ballast.
3-32

Power factors range between 0 and 1. A power factor of 1 indicates that the voltage and current 

waveforms are in phase; a power factor of 0 indicates that voltage and current are ninety degrees 

out of phase and that no real power is being transferred. Metal halide ballasts can be 

characterized by two classes of power factor: high power factor (HPF) of 0.9 or greater and 

normal power factor (NPF) of 0.6 or greater. HPF ballasts use about one-half the current of NPF 

ballasts. For magnetic ballasts, the primary cause of low power factor is the inductance of the 

ballast transformers. It can be corrected with the addition of a suitable capacitance. In electronic 

ballasts, low power factor is due primarily to total harmonic distortion (defined in the following 

section 3.3.3.4) caused by a nonlinear load. According to ANSI C82.77-2002, commercial metal 

halide lamp ballasts must have a HPF while residential ballasts (with an input power less than 

120 W) must have a power factor of 0.5 or greater.

3.3.3.4 Total Harmonic Distortion

Another important performance parameter is harmonic distortion. Line current harmonics 

are the components of the line current that oscillate at integer multiples of the fundamental 

frequency of the power supply (e.g., 60 Hz, 120 Hz, 180 Hz). Harmonics of a fundamental 

frequency are an undesirable byproduct of any nonlinear system operation, generating noise and 

wasted power. Total harmonic distortion refers to the ratio of the root mean square (rms) values 

of the harmonic content and of the fundamental current, expressed as a percentage. It may also 

be called harmonic factor:

2

1

2

4

2

3

2

2 ... ( )

I

I I I

THD fund

+ + + =

Eq.3.2

Where: 

THD = total harmonic distortion, and 

I n = the rms current of harmonic n, where n=1 is the fundamental harmonic.

High THD values are not acceptable and are detrimental to many kinds of electronic 

devices connected to the power line. They are also considered a “pollutant” to the environment 

because of radio frequency noise. In related electronic fluorescent lamp ballast products, ANSI 

C82.11-2002 requires that the THD not exceed 32%. Metal halide ballast manufacturers also try 

to limit the THD of their products to reduce compatibility concerns with nearby devices.

3.3.3.5 Ballast Factor

In contrast with other forms of lighting, metal halide lighting is not usually understood in 

terms of ballast factor, a measure of relative light output.

3.3.3.6 Electromagnetic Interference
3-33

Many devices found in office environments, such as computers, photocopiers, facsimile 

machines, and HID lighting systems, can generate electromagnetic waves. The effects of these 

waves vary based on their strength and the susceptibility of nearby equipment. Alternating 

current (AC) in electronic devices produces a magnetic field, which in turn induces an AC 

voltage in a nearby electronic device. This process is considered EMI if it interferes with the 

operation of a device. EMI takes two forms: conducted or radiated. Conducted EMI occurs when 

electronic devices induce currents in the local power network that in turn negatively affect other 

devices on that network. Radiated EMI is associated with the electric and magnetic field inherent 

in electronic devices. EMI can be minimized with proper grounding and wiring techniques.18

3.3.3.7 Transient Susceptibility

EMI limits for both consumer and non-consumer lighting products sold in the United States are 

listed in 47 CFR 18 subpart C. These regulations require that consumer/residential (Class B) 

ballasts have lower maximum EMI requirements than non-consumer (Class A) products. The 

International Committee on Radio Interference has more stringent regulations concerning EMI.

Metal halide lamp fixtures are frequently used in applications that have the potential for 

voltage spikes and surges caused by lightning strikes, switching contacts, and inductive loads. 

These transients pose a serious threat to ballast operation. While magnetic ballast are somewhat 

rugged and can withstand 15 to 20 kV, electronic ballasts are more susceptible to drastic changes 

in voltage and generally cannot withstand a transient greater than 6 kV. In both cases, the ballasts 

can be protected by arrestors that either run the interference into the ground, or absorb the excess 

flow of current. Such measures are incredibly important for electronic ballasts; the preferred 

arrestor technology to protect the ballast against transients is silicon oxide varistors (SOVs)i

3.3.3.8 Fitted Form

. 

SOVs consist of a pair of metal electrodes separated by a silicon oxide compound. Under normal 

conditions, the silicon oxide is a good insulator so that no line current flows between the 

electrodes to ground. When an excessively high voltage occurs on the electrodes, the high energy 

electrical field ionizes the silicon oxide. Since the silicon ion is a good conductor, the high 

energy current is conducted to ground. When the voltage falls toward normal, the silicon and 

oxygen ions recombine, forming silicon oxide and shutting off the conduction. Electronic metal 

halide lamp ballasts require approximately 10 kV surge suppressors in order to be installed safely 

in most outdoor applications. 

Magnetic and electronic ballasts come in a variety of form factors to accommodate 

different applications. Although electronic ballasts have been well miniaturized for low-wattage, 

indoor applications (e.g., track lighting), thermal requirements make volume reduction difficult 

at higher wattages. While electronic ballasts tend to be monolithic, magnetic ballasts often have 

two or more pieces that can be arranged within a given fixture. Furthermore, electronic ballasts 

might require special mounting within a fixture for heat sinking. Nonetheless, some 

manufacturers have begun to market electronic ballasts that are “drop-in” replacements for 

magnetic units.

3.3.3.9 Dimming

 i

A similar function can be performed by metal oxide varistors (MOVs).
3-34

Dimming, or the practice of intentionally operating a lamp at less than its rated output, 

holds enormous energy saving potential. In many lighting applications, it is important to have the 

ability to quickly summon full output, but less important to have it all the time. Examples of this 

might be roadways with infrequent traffic, daylight-harvesting buildings, untraveled warehouse 

aisles, and vacant parks. In certain applications, dimming may be a cost-effective path toward 

energy savings. A ballast dimmed to 50 percent input power half of the time would, 

mathematically, consume 25 percent less energy than that same ballast operated always at full 

output. Depending on the marginal cost of adding dimming capability, it might be far less 

expensive than purchasing a ballast that were natively 25 percent more efficient (if such a ballast 

were even available). 

Dimming metal halide lamps, however, is not without its challenges. Lamps are designed 

to stabilize at a certain temperature, of which light color and lamp life are a function. As color 

temperature and color rendering index (CRI) are often reasons for choosing metal halide lighting 

over competing technologies, some applications will find color shift unacceptable. Furthermore, 

many lamp manufacturers recommend that their lamps be dimmed to not lower than 50 % of 

rated power. While this may be a good step toward saving energy, it may be inadequate for 

aesthetic or “mood” lighting. Although electronic ballasts can usually dim continuously from full 

to minimum output, and back, magnetic ballasts are usually constrained to stepped dimming, 

oftentimes only to full and half power. Finally, while the cost of a dimming ballast might not far 

exceed that of a non-dimming ballast, costs of hardware needed to regulate the dimming (e.g., 

photosensors, radio receivers, relays, wiring) could be considerable.

Dimming has been successfully used to save energy in a variety of lighting 

technologies.

Electronic and magnetic ballasts accomplished dimming in different, but analogous, ways. 

Because many electrical components have properties that vary with frequency, operating power 

transistors at higher or lower frequencies is a convenient way to limit power transfer to the lamp. 

Although magnetic ballasts have no ability to modulate frequency, they will change the electrical 

properties of their circuits in different ways. Constant-wattage autotransformer ballasts 

(discussed further in section 3.3.4.1) might use a bi-level capacitor, for example, switched by a 

relay between the two capacitances.

3.3.3.10 Magnetic Ballasts

Metal halide magnetic ballast technology is older than electronic ballast technology, and 

used today for its low cost and tolerance of harsh environments. The primary feature of a 

magnetic ballast is one or more coils of magnet wire around an iron core; because of this they are 

often called “core-and coil” ballasts. Apart from the igniter of pulse-start ballasts, magnetic 

ballasts contain no power electronics and are, therefore, better equipped to survive voltage 

transients and high temperatures.

The main components of a magnetic ballast are a magnetic choke to limit the current, a 

step-up transformer to obtain a high starting voltage, and a capacitor that corrects for the ballast’s 

low power factor. Magnetic ballasts operate at an input frequency of 60 Hz and operate the 

lamp(s) at the same frequency.
3-35

The main core-and-coil assembly consists of a capacitor and laminated transformer steel 

wound with copper or aluminum magnet wire. The assembly is infused with a potting material 

(e.g., hot asphalt, epoxy) containing fiber such as silica and housed in a steel case. Figure 3.3.14

presents a view of a typical core and coil assembly.

Source: GE Lighting

Figure 3.3.14 Core and Coil Assembly of a Magnetic Ballast

The core and coil assembly functions as a voltage transformer and current limiter 

(choke). A capacitor enables the ballast to use energy from the alternating current power line 

more efficiently, which is then referred to as a HPF or PF corrected ballast. The purpose of the 

insulating material is to conduct heat away from the transformer coils and ensure tightness of the 

transformer coils to eliminate vibration noise.

Particularly at lower wattages, magnetic ballasts are less energy efficient than electronic

ballasts. Magnetic ballasts fail to optimize lumen output for a given wattage. These ballasts also 

release energy not used to operate the lamp as heat in the transformer windings. In order of 

increasing cost and complexity, metal halide lamp magnetic ballasts have the following types of 

circuits: linear reactor (reactor), high-reactance autotransformer (HX-HPF), constant wattage 

autotransformer (CWA), constant wattage isolated (CWI), and magnetically regulated lag (magreg or reg-lag). In general, extra circuitry helps the ballast maintain a constant power output 

through variations in input voltage.

Linear Reactor

Reactor ballasts are the simplest, smallest, cheapest, and most efficient type of magnetic 

ballast. Though a capacitor is often employed for power factor correction, a reactor ballast can be 

as simple as a mere inductor in series with the load. It drops more voltage as current increases, 

stabilizing lamp current at the appropriate point. The major drawback of a reactor ballast is its 

susceptibility to line voltage variation; the commonly used ratio is a 5% voltage dip produces a 

greater than 10% power dip. Furthermore, the ballast has no ability to modify voltage, meaning 

the line voltage must be sufficient to run the lamp, often limiting reactor ballasts to 277 V 

applications.

High-Reactance Autotransformer
3-36

With high-reactance autotransformers, the addition of a capacitor to the primary circuit 

makes it possible for the ballast to provide a high power factor. The high power factor 

autotransformer is usually designed with an extra capacitor winding within its copper windings 

in order to provide a more economical and efficient system. The HID ballast’s power factor can 

be increased to about 90% by combining the extended windings with the capacitor. The input 

current is reduced, as in the high power factor reactor. Lamp performance and regulation are also 

the same at plus or minus 5%. Currently, HX ballasts account for the majority of sales of 

magnetic ballasts rated at or less than 150 W.

Constant-Wattage Autotransformer

The CWA HID ballast type should be used where a stabilized light output is required. 

CWA is an HID ballast type that comes in a fairly small economical size, yet still provides a 

reasonable degree of regulation. The CWA ballast also offers the advantage of a high power 

factor, low line extinguishing voltage, and line starting currents that are lower than operating 

currents. The CWA type of ballast is the most commonly used ballast in North America today. 

Unlike the HX-HPFs, which use a capacitor as a parallel component, the capacitor on a 

CWA ballast type is used in series with the lamp. This alignment provides the lamp with a more 

stable wattage when voltage on the branch circuit fluctuates. As the capacitor is performing an 

important ballasting function, it is referred to as a lead circuit. CWA is the most common ballast 

topology, for its ability to resist line voltage changes and for its lower starting current demands. 

Although some CWA units rated for lower than 150 W are sold, wattages higher than 150 W are 

firmly CWA territory.

Constant-Wattage Isolated Transformer

CWI ballasts are nearly identical to CWA ballasts in both structure and function, the 

primary difference being a conventional two-coil transformer in place of the single-coil 

autotransformer. At a very slight efficiency cost, CWI ballasts provide better protection against 

voltage transients, as the low and high sides of the ballast are coupled only magnetically. Though 

common in Canada, few CWI ballasts are sold in the United States.

Magnetically Regulated Lag

Reg-lag ballasts are the largest, heaviest, and most expensive topology. Three distinct 

circuits collaborate to provide the greatest degree of resistance to voltage variation, and reg-lag 

ballasts may even sustain lamps through voltage drops of 30%. Reg-lag ballasts were exempted 

from standards in EISA 2007, and account for a very small (less than one percent) fraction of the 

North American ballast market. Due to their large size and high cost, reg-lag ballasts are unlikely 

to be substitutes for CWAs or other ballast types.

3.3.3.11 Electronic Ballasts

Depending on wattage, electronic ballasts might be between 2 and 20% more efficient 

than their magnetic counterparts. Electronic ballasts can be roughly divided into low- and highfrequency types which, respectively, operate lamps far below or above frequency ranges prone to 

acoustic resonance. Most low-frequency (LF) ballasts drive their lamps with a “square” wave, 
3-37

while high-frequency (HF) units usually produce sinusoids. Although HF units are thought by 

some to be more efficient because of smaller circuitry components and the elimination of a 

power processing stage from the ballast, metal halide efficiencies do not scale with frequency the 

same way fluorescent efficiencies do; high efficiency electronic ballasts can be found operating 

at both high- and low-frequencies.

Figure 3.3.15 presents a functional block diagram example of a fixed-light output 

electronic ballast. Auxiliary functions performed by a typical electronic ballast include EMI

filtering to block ballast-generated noise, input rectification, PF correction for sinusoidal input 

current, a direct-current (DC) filter, a direct-current to alternating-current (DC-AC) inverter, a 

feedback/controller for high-frequency operation, and a final output stage to power the lamp.

Figure 3.3.15 Electronic Metal Halide Ballast Block Diagram

Source: T. Ribarich, A Systems Approach to Ballast IC Design, El Segundo, CA, 1999, and Philips Semiconductor, 

Power Semiconductor Applications, 1994.

Figure 3.3.1 provides a description of each component in a typical electronic metal halide 

lamp ballast, the efficiency impact of these components, and the waveform at each stage of the 

ballast circuit.

Table 3.3.1 Basic Building Blocks of a Metal Halide Lamp Ballast and Associated 

Characteristics

Circuit Stage Function Efficiency 

Impact

Waveform (not to 

scale)

EMI Filter

Impedes EMI by providing a high impedance 

path to EMI and a low impedance path to the 

desired input. The circuit also protects against 

high voltage pikes.

Very Low

t

V
3-38

Input Rectifier

Begins to convert incoming AC to DC using 

diodes. A full-bridge rectifier, one type of 

input rectifier, is composed of four diodes, 

which “rectify” the full AC waveform as 

shown in the waveform on the right. The 

current is not in phase with the voltage.

Low

Power Factor 

Correction

Corrects the current so it is in phase with the 

voltage. Power factor correction can be 

achieved through a buck or boost-converter 

circuit topology.

Low-Medium

DC Filter

Reduces “ripple” of the DC current waveform 

using capacitors. The most common type of 

capacitor used is the electrolytic capacitor.

Low

DC-AC Inverter

Converts incoming DC to high-frequency AC. 

The resonant half-bridge self-oscillating 

circuit is one type of circuit topology that can 

be used to accomplish this task.

MediumHigh

Output Stage

When the lamp is not started, the circuit 

operates in resonance to increase output 

voltage to start the lamp. Once the lamp is 

started, the circuit operates at a frequency off 

of resonance to continue operating the lamp. 

A resonant filter topology is one type of 

circuit topology used in the output stage.

High

Starting:

Operation:

t

V, I

t

V, I

t

V

t

V

t

V
3-39

Feedback/Controller

An integrated circuit (IC) that controls the 

frequency output of the DC-AC inverter. It 

can also protect against under voltage lockout 

and lamp faults.

Low N/A

3.3.4 Metal Halide Lamp Ballast Technology Options

When analyzing equipment efficiency potential, DOE first identifies all of the different 

ways efficiency could be improved. These technology options are later evaluated on the basis of 

four statutorily-prescribed criteria, after which the remaining selections are called design options. 

The following sections describe technology options for incrementally improving the efficiency 

of magnetic and electronic ballasts included in metal halide lamp fixtures.

3.3.4.1 Magnetic Ballasts

There are four main ways of reducing losses in magnetic ballasts: improving the core 

steel, using copper conductor, increasing the stack height, and increasing conductor crosssection.

Improved Core Steel

Electrical steel, placed in a time-variant magnetic field, loses energy in two ways. Eddy 

currents are small, unproductive currents that dissipate energy resistively, whereas hysteresis is a 

nonlinearity in the magnetization of a material in response to the magnetic field applied. 

Electrical steels are made in different grades that correspond to different losses. Inexpensive 

magnetic ballasts typically use non-oriented steel whose magnetic properties are isotropic. 

Higher grades of steel can be grain-oriented, where the microscopic structure of the material is 

optimized for a particular field direction, or amorphous, which has no grain structure at all and 

the most desirable magnetic properties.

Copper Conductor

Most inexpensive magnetic ballasts use aluminum conductor, which is more resistive 

than copper conductor of the same gauge. Because conductor losses vary in proportion to the 

resistance of the conductor, lowered resistance yields lower losses and higher ballast efficiency.

t

V
3-40

Increased Stack Height

Losses in electrical steel vary with magnetic flux density, with higher flux density 

yielding higher losses. For a given magnetic field, increasing core cross-section will lower flux 

density and, therefore, lower losses. Because steel laminations are said to be “stacked” to form a 

core, increasing core cross-section is ordinarily done by adding steel laminations, or increasing 

the stack height. However, adding steel also adds core losses in the form of eddy currents and 

hysteresis, and also requires a greater length of conductor, eventually offsetting decreased core 

losses from increased core cross-section.

Increased Conductor Cross-Section

The efficiency of a magnetic ballast could be increased with the use of increased 

conductor cross-sections in the windings of the magnetic choke and step-up transformer. This 

can be accomplished by both using larger wire gauges (i.e., lower numeric values), multiple 

strands of wire operating in parallel. Using greater cross-sectional area in the magnetic 

component windings decreases the winding resistance and associated losses. Increased crosssectional area in the windings could necessitate a longer core or additional layers of wire if the 

core length cannot be changed to maintain the same electromagnetic properties. This design 

option typically corresponds to an increase in manufacturing cost.

3.3.4.2 Electronic Ballasts

Electronic ballasts contain a wide variety of components and circuit types, leading to 

many paths to increased ballast efficiency. DOE organized these options into two categories, 

improved components and improved circuit designs. In addition, the use of electronic ballasts 

instead of magnetic ballasts is also a path to increased efficiency for many wattage ranges. 

Electronic ballasts use modern, solid-state components and circuits to perform the same function 

as magnetic ballasts with lower electrical losses.

Improved Components

A common way to increase the efficiency of electronic ballasts is to improve the quality 

of their components. Magnetics (transformers and inductors), diodes, capacitors, and transistors 

are the main components that affect efficiency. 

Magnetics: In electronic ballasts, magnetics influence the efficiency of the EMI filtering, 

PFC, and output stage of the ballast. In magnetic ballasts, magnetic components influence the 

efficiency of the output stage and current-limiting portion of the ballast. 

There are two loss mechanisms associated with magnetics: core losses and winding 

losses. Core losses involve the magnetic properties of the core material, which exhibits power 

losses in the form of hysteresis and eddy currents within the core itself. Winding losses come 

from the resistance in the winding, typically aluminum or copper. There are several technology 

options that can decrease magnetic component’s core losses. These options include improved 

materials such as silicon steel and amorphous steel and increased core size. Litz wire can be used 

as a technology option to improve a magnetic component’s winding losses.
3-41

Core losses in magnetic components can be decreased through four main methods. The 

material of the core can be varied. DOE has identified two types of core materials that ballasts 

can use: silicon steel (thinly laminated steel alloyed with silicon) and amorphous steel. Core 

performance of silicon steel can be enhanced by magnetically aligning the grain structure in the 

metal. To further increase the efficiency of the ballast using amorphous materials, one can create 

the core of the magnetic component from laminated sheets of amorphous steel, insulated from 

each other. However, this method can increase the size and weight of the ballast. Additionally, 

the magnetic component’s core can be designed with a larger cross-section (increased stack 

height) to reduce core losses, though this method also increases the size and weight of the ballast.

Winding losses in magnetic components can be decreased via three main methods.

Different materials have different resistive properties and can result in different winding losses. 

Aluminum is the most basic (least efficient) material currently used. Copper is more conductive, 

and with its gauge size optimized for wattage, voltage, and current specifications, and the 

number of windings increased, winding losses can decrease relative to aluminum. Winding 

losses can also be decreased within any material type by increasing the cross section of the wire 

used for the windings. Finally, for high-frequency electronic ballasts, winding losses become 

more prominent through two additional loss mechanisms: skin effect and proximity effect. Skin 

effect refers to the tendency of AC current to flow through a conductor’s surface or “skin” rather 

than a conductor’s core. Proximity effect occurs when conductors are close together and the 

magnetic field of one conductor reduces the area that the current flows through in another 

conductor. Litz wire has even lower losses as it consists of a number of individually insulated 

magnet wires twisted or braided into a uniform pattern. Because litz wire increases the amount of 

surface area current can flow through, its use can reduce overall winding losses by decreasing the 

effective wire resistance.

Diodes: In electronic ballasts, the input rectifier inverts the negative half of the AC sine 

wave and makes it positive. Several technology options can be used to improve the efficiency of 

this portion of the circuit. The power consumed by a diode is the product of the current flowing 

through the diode multiplied by the voltage drop across it. Conventional diodes have a voltage 

drop of about 0.6 V. Using Schottky diodesj

Capacitors: In both magnetic and electronic ballasts, capacitors are used in the PFC and 

output stage of the circuit design. In electronic ballasts, capacitors are also used in the DC Filter 

stage of the electronic circuit. One way to improve the efficiency of each portion of the circuit is 

to use capacitors with low effective series resistance (ESR). Capacitors with a low ESR are also 

more reliable because they are cooler than capacitors with a higher ESR.

could reduce the voltage drop across the diodes by 

about 0.3 V to 0.4 V. 

Transistors: In electronic ballasts, transistors are used in both the power factor correction 

and the DC-AC inverter portion of the circuit. The transistor dissipates energy due to its drain-tosource resistance (RDS_ON) when the current flows through the transistor to the transformer. 

Using transistors with low RDS_ON can reduce this loss. For example, the efficiency of electronic 

ballast’s bipolar transistors can be improved by using metal-oxide-semiconductor field-effect 

 j

A Schottky diode is a metal semiconductor diode with a smaller voltage drop than a conventional diode. Schottky 

diodes therefore consume less power. 
3-42

transistors (MOSFETs), a transistor with a lower drain-to-source resistance. In addition, 

transistors with lower capacitance can reduce switching losses.

Improved Circuit Design

Another method of increasing the efficiency of electronic ballasts is to improve the 

ballast’s circuit design. Examples of improved circuit design include integrated circuits and

improved starting method.

Integrated Circuits: In certain cases a ballast’s efficiency can be improved by substituting 

integrated circuits for discrete components. For example, some ballasts use bipolar transistors in 

a resonant half-bridge self-oscillating circuit to convert incoming DC to AC. The efficiency of 

this circuit can be improved by substituting the components in that circuit with an integrated 

circuit. Though the inclusion of ICs alone does not automatically increase efficiency, ICs allow 

for more advanced control of other components, which can lead to increased ballast efficiency.

3.4 EQUIPMENT CLASSES

When evaluating and establishing energy conservation standards, DOE divides covered 

equipment into classes by the type of energy used, capacity, or other performance-related 

features that affect efficiency, and factors such as the utility of the equipment to users. (See 42 

U.S.C. § 6295(q)) DOE then conducts its analysis and considers establishing or amending 

standards to provide separate standard levels for each equipment class. DOE applied the criteria 

of 42 U.S.C. § 6295(q) to metal halide lamp fixtures to develop equipment classes for this 

preliminary TSD. This section describes the equipment classes DOE considers for this 

rulemaking.

In amending EPCA, EISA 2007 effectively set four equipment categories for metal halide 

lamp fixtures based upon the ballasts used and the wattage of the lamps in those fixtures. In 

prescribing initial energy conservation standards for metal halide lamp fixtures, the statute 

established minimum efficiency requirements for the metal halide lamp ballasts contained in 

those fixtures. (42 U.S.C. § 6295(hh)(1)(A)) The current equipment categories for metal halide 

lamp fixtures are presented in Table 3.4.1.
3-43

Table 3.4.1 EPCA Equipment Categories Established by EISA 2007 for Metal Halide 

Lamp Fixtures (by Ballast Type and Lamp Wattage)

Ballast Type and Starting 

Method

Total Rated Lamp Watts

Pulse-Start ≥ 150 W and ≤ 500 W 

Magnetic Probe-Start ≥ 150 W and ≤ 500 W 

Non-Pulse-Start Electronic

≥ 150 W and ≤ 250 W 

> 250 W and ≤ 500 W

The equipment categories for metal halide lamp fixtures set forth in Table 3.4.1 are a 

composite of ballast type and lamp wattage. For pulse-start metal halide ballasts, EPCA does not 

distinguish by electronic configuration (magnetic or electronic), so fixtures with either type of 

pulse-start ballast would be subject to the statutory standards. Pulse-start, magnetic probe-start, 

and non-pulse-start electronic ballasts are considered separately, with two rated lamp wattage 

ranges identified for the latter, resulting in a total of four equipment categories. In addition, EISA 

2007 exempts fixtures that contain certain ballasts such as regulated lag ballasts and electronic 

ballasts that operate at 480 volts.

In addition to the metal halide lamp fixtures identified in Table 3.4.1, the metal halide 

lamp fixture market includes fixtures that contain ballasts that operate low-wattage (i.e., less than 

150 W) and high-wattage (i.e., greater than 500 W) lamps. DOE has also examined recent 

market trends. For example, pulse-start ballasts are gaining market share, whereas probe-start 

ballasts are becoming less popular and consequently, losing market share. This market shift has 

accelerated in 2009. Based on review of catalog information of commercially-available 

equipment, the standard levels (i.e., the ballast efficiencies) established by EISA 2007 for metal 

halide lamp fixtures have essentially eliminated magnetic probe-start ballasts from the 

marketplace by requiring a ballast efficiency that is not currently attainable with electromagnetic 

ballast technology. Therefore, this trend is expected to continue. Due to market changes, and 

because DOE is anticipating expanding its scope of energy conservation standards for metal 

halide lamp fixtures, DOE is considering amending the equipment classes for these fixtures and 

their associated ballasts. When determining equipment classes, DOE examines characteristics or 

features commonly found in commercially-available equipment. For metal halide lamp fixtures, 

DOE examined several possible characteristics or features that could warrant separation into 

different equipment classes, including: (1) rated lamp wattage; (2) input voltage; (3) number of 

lamps per ballasts; (4) lamp starting method; (5) electronic configuration and circuit type; and (6) 

fixture application. Each of the listed characteristics or features is discussed in the following 

sections.
3-44

3.4.1 Rated Lamp Wattage

Metal halide lamp ballasts are available for lamps with rated wattages as low as 20 W and 

as high as 2,000 W. Depending on the application, a specific or minimum light output is 

necessary. Lamp wattage affects light output with increasing wattage lamp and ballast systems 

generally producing increasing amounts of light. Consumers require varying amounts of light 

depending on application. For example, low-wattage (less than 150 W) lamps are mainly used in 

commercial and some residential applications for general lighting purposes. Medium-wattage 

(150-500 W) lamps are the most widely used and include warehouse, street, and general 

commercial lighting. High-wattage (greater than 500 W) lamps are mainly used in searchlights, 

stadiums, stage applications, and other applications that require powerful white light. The 

wattage of the lamp and ballast system provides a consumer utility based on its impact on light 

output. DOE also determined that the wattage of the lamp and ballast system also impacts the 

efficiency of the ballast. Generally, ballast efficiency increases with increasing power. For 

electronic ballasts, this efficiency gain can be attributed to the proportion of fixed losses to total 

losses. For low wattage electronic ballasts, fixed losses contribute to a larger proportion of total 

losses than in a high wattage ballast. Magnetic ballasts are essentially transformers (sometimes 

with capacitors for power correction and ignitors for pulse-starting), which are understood to 

have proportionally lower losses with increased wattage. Because wattage can affect both 

consumer utility (light output) and efficiency, DOE has preliminarily decided to establish 

separate equipment classes on the basis of wattage.

EISA 2007 defines equipment classes with a single rated lamp wattage range (150–500 

W) for both pulse-start and probe-start metal halide lamp ballasts. For non-pulse-start metal 

halide lamp ballasts, EISA 2007 separates equipment classes into two rated lamp wattage ranges 

(≤250 W and >250 W). For the framework document, DOE considered defining metal halide 

lamp fixture equipment classes by including additional lamp wattage ranges. DOE considered 

including (1) <150 W, (2) ≥150 W and ≤250 W, (3) >250 W and ≤500 W, and (4) >500 W as 

separate wattage bins to establish a separation of equipment classes.

DOE carried out additional analysis on the shipment volume and range of efficiencies 

available in a <150 W class. DOE’s efficiency test results for a ballast wattage representative of 

the low-wattage class (70 W) confirmed that lower wattage ballasts have significant differences 

in efficiency depending on the technology (i.e., electronic or magnetic ballast). In terms of 

shipment volume, manufacturers indicated during interviews that lower wattage shipments 

predominantly fall between 50 W and 150 W, not the <50 W category. Based on the shipment 

volume and comments received, DOE proposes ≥50 W and <150 W as the lowest wattage bin 

range. DOE chooses a representative unit in the engineering analysis to ensure technological 

feasibility of all product in the ≥50 W and <150 W class.

For today’s rule, DOE is considering defining the metal halide lamp fixture equipment 

classes by the rated lamp wattage ranges ≥50 W and <150 W, ≥150 W and ≤250 W, >250 W and 

≤500 W, and >500 W.

3.4.2 Input Voltage
3-45

During interviews and further research of the market, DOE learned that the majority of 

available metal halide ballasts have the capability to operate at different voltages or have 

multiple voltage “taps” with different voltages for each tap. Multi-taps and multiple voltages 

benefit consumers and manufacturers by decreasing SKU count, allowing the operation of 

auxiliary equipment, and lowering costs by decreasing part counts and variations of ballasts. 

DOE’s test results for ballast efficiency showed that although voltage can correlate weakly to 

efficiency, there is no prevailing relationship (e.g., higher voltages are not always more efficient) 

across ballast designs. However, DOE did examine the > 300V category (using 480 V ballasts as 

a proxy) to more fully understand this subgroup. 

To study the impact of the ability to operate at 480V, DOE first compared quad-inputvoltage ballasts (ballasts able to operate at 120, 208, 240, and 277 V) and dedicated 480 V units. 

DOE found that the quad-input-voltage ballasts were, on average, 1.2% more efficient. DOE also 

compared quad- and quint-input-voltage ballasts (ballasts that are able to operate at 120, 208, 

240, 277, and 480 V). DOE found that the quad-input-voltage ballasts were, on average, 0.4% 

more efficient.

DOE preliminarily plans to not separate equipment classes by voltages. However, does 

plan to further consider a separate product class for ballasts capable of operating at 480 V in later 

stages of this rulemaking.

3.4.3 Maximum Number of Lamps Operated

A review of manufacturer catalogs shows that while the vast majority of available 

ballasts only operate one lamp, a much smaller number are designed for two lamps. The limited 

catalog information available shows little to no change in efficiency between a one-lamp or twolamp metal halide ballast. Thus, DOE tentatively decided not to establish separate equipment 

classes based on maximum number of lamps operated.

3.4.4 Lamp Starting Method

Metal halide lamp ballasts currently available in the market are specifically designed to 

operate with either a probe-start or pulse-start lamp, but not both types of lamps at the same time. 

The main differences between these types of starting methods is the inclusion of a third probe in 

probe-start lamps, the need for an igniter circuit for pulse-start lamps, and the different wiring 

specification for ballasts of each starting method. Most new applications in the market are pulsestart due to its inherently better efficacy. However, with minor changes to the wiring 

specification and configuration within a fixture as well as the swap of lamp type, probe-start 

ballasts can be replaced by pulse-start ballasts. Manufacturers also have developed pulse-start 

retrofit kits for existing probe-start applications.

For today’s rule DOE does not further divide equipment classes by the ballast starting 

method (e.g., pulse-start or probe-start). DOE’s initial view is that equipment classes should not 

be further divided by starting method due to their interchangeability and lack of unique or 

separate utility that would affect efficiency. To prevent violation of anti-backsliding provisions 

under EISA, DOE will maintain EISA minimum ballast efficiency requirements for fixtures with 

probe-start ballasts if the analysis in this rulemaking does not support amending standards to a 
3-46

more stringent level relative to EISA. DOE is considering whether a design standard that would 

eliminate probe start would result in significant energy savings.

3.4.5 Electronic Configuration and Circuit Type

Metal halide lamp ballasts have two distinct types of electronic configuration: electronic 

and electromagnetic (magnetic). The more commonly used magnetic ballasts are typically 

composed of transformer-like copper windings on a steel or iron core. The newer and more 

efficient electronic ballasts rely on electronic filters, switches, and capacitors/inductors to control 

current and voltage to the lamp.

In metal halide lamp fixtures, electronic ballasts can be used to achieve higher efficiency 

than magnetic ballasts. In the current metal halide lamp fixtures market, electronic ballasts are 

direct replacements for magnetic ballasts for most lower to medium wattage applications (up to 

500 W). DOE’s review of manufacturer catalogs shows that at higher wattages, few electronic 

ballasts are available due to the significantly higher cost of components. For electronic ballasts, 

the only difference in circuit type is either “high” or “low” frequency circuit type. Due to 

acoustic resonance issues and electromagnetic interference (EMI) effects, ballast frequencies 

above 300 Hz become difficult to manufacture and have difficulty complying with Federal 

Communications Commission (FCC) standards.k

EISA 2007 distinguishes non-pulse-start electronic equipment classes by separating them 

into two rated lamp wattage ranges (≥150 W and ≤250 W, and >250 W and ≤500 W). According 

to DOE’s review of manufacturer catalogs and information provided by manufacturers during 

interviews, non-pulse-start electronic metal halide lamp ballasts are not available in the market. 

While EISA 2007 provisions may have been intended to capture alternative technologies that 

could be available in the near term, DOE has no information that indicates differences in 

efficiency or consumer utility based on pulse versus non-pulse-start ballasts. Therefore, DOE 

does not believe equipment classes should be divided by electronic configuration.

For low-frequency electronic ballasts, a square 

current waveform is used to diminish acoustic resonance and maintain lamp life. Though 

electronic ballasts are commonly more efficient than magnetic ballasts, neither configuration 

provides a distinct consumer utility over the other. Both types are capable of producing the same 

amount of light and can be used interchangeably.

Magnetic metal halide lamp ballasts are available in the market in several circuit types

including high-reactance autotransformer, constant-wattage isolated transformer, constantwattage autotransformer (CWA), linear reactor (reactor), and magnetically regulated lag (reg-lag 

or mag-reg) ballasts. Each magnetic circuit type listed has different characteristics that could 

have separate applications. These characteristics include size, efficiency, and power regulation. 

Each of these characteristics is discussed in section 3.3.4.1. For example, magnetically regulated 

lag ballasts are typically the largest and heaviest circuit type, but provide the greatest degree of 

resistance to input voltage variation (which sustains light output).

 k FCC regulations at 47 CFR part 18, subpart C set forth technical standards for industrial, scientific, and medical 

equipment that specify frequency bands and ranges tolerances as well as electromagnetic fields strength limits. 

Some metal halide lamp ballasts may be covered under these “industrial, scientific, and medical (ISM) equipment” 

standards, which list the general operating conditions for ISM equipment. Ballasts designed to exceed 9 kHz ballast 

frequency have to be designed so that interference with transmitted radio frequencies is eliminated. 47 CFR 18.111. 
3-47

Because electronic ballasts can provide the utility included in any magnetic circuit type, 

can be used as substitutes in all applications, and are generally more efficient than magnetic 

ballasts, DOE is not setting separate equipment classes based on electronic configuration 

(magnetic vs. electronic) or on circuit type. However, if appropriate, DOE could further divide 

equipment classes by either of these parameters based on any new data indicating that separation 

is warranted.

Fixture Application

DOE has preliminarily determined to set energy conservation standards based on a ballast 

efficiency metric. DOE’s research has tentatively determined that the same efficiencies can be 

achieved in all applications (including outdoor and indoor) by the same or similar products. DOE 

also found that electronic ballasts have been successfully applied to a variety of both indoor and 

outdoor applications where temperature and other limiting conditions could hinder their 

implementation. In the context of a ballast efficiency metric, DOE also believes defining product 

types and applications for equipment classes is difficult and subjective. DOE does not plan to 

further divide equipment classes by application. 

3.4.6 Equipment Classes Summary

For all the reasons discussed, DOE is considering the metal halide lamp fixture equipment 

classes listed in Table 3.4.2. Of the six discussed possible characteristics and features that 

differentiate metal halide lamp fixtures, DOE is considering rated lamp wattage. This is because 

rated lamp wattage affects lamp utility and efficiency. Due to limited information and lack of 

clear effect on utility or performance, DOE does not divide the equipment classes based on the 

other types of characteristics and features. Chapter 5 of this preliminary TSD provides detail on 

the selection of candidate standard levels.

Table 3.4.2 Equipment Classes for Metal Halide Lamp Ballasts

Rated Lamp Wattage Equipment 

Class

≥ 50 W and < 150 W 1

≥ 150 W and ≤ 250 W 2

> 250 W and ≤ 500 W 3

> 500 W 4

 

1 Ron Runkles. NEMA Premium Efficiency Electronic Ballast Program. NEMA Lighting Systems 

Division. 2007. (Last accessed March 24, 2011). <http://www.cee1.org/cee/mtg/09-

07ppt/Wednesday/9%20NEMA_CEE%20Presentation.ppt>. 

2 National Electrical Manufacturers Association. Lighting Systems Division. 2002. (Last accessed 

March 24, 2011). <http://www.nema.org/prod/lighting/upload/LightingSystemsDivision.pdf>. 
3-48

 3 U.S. Small Business Administration. Table of Small Business Size Standards Matched to North 

American Industry Classification System Codes. 2008. (Last accessed March 24, 2011). <

http://www.sba.gov/sites/default/files/Size_Standards_Table.pdf>. 

4 U.S. Small Business Administration. Table of Small Business Size Standards Matched to North 

American Industry Classification System Codes. 2008. (Last accessed March 24, 2011). <

http://www.sba.gov/sites/default/files/Size_Standards_Table.pdf>. 

6 U.S. Environmental Protection Agency and U.S. Department of Energy. About ENERGY 

STAR. (Last accessed March 24, 2011). 

<http://www.energystar.gov/index.cfm?c=about.ab_index>.

7 Northeast Energy Efficiency Partnerships. Commercial Buildings and Technology Initiative. 

(Last accessed March 24, 2011). http://neep.org/regional-initiatives/1/56/Commercial-Buildingsand-Technology-Initiative.

10 U.S. Census Bureau. Manufacturing, Mining, and Construction Statistics. Current Industrial 

Reports, Electric Lamp Fixtures, MA335L. (Last accessed April 26, 2010). 

<http://www.census.gov/mcd/>

11 Lighting handbook, downlight definition IESNA, The IESNA Lighting Handbook: Reference 

and Application, 2000.

12 Lighting handbook, uplight definition IESNA, The IESNA Lighting Handbook: Reference and 

Application, 2000.

13 Advanced Energy Design Guide for Small Warehouse and Self-Storage Buildings, American 

Society of Heating, Refrigeration and Air-Conditioning Engineers, Inc, 2008.

14 National Lighting Product Information Program, Specifier Reports: Occupancy Sensors, 

Volume 5 No. 1, May 1997.

15 http://www.americanlightingassoc.com/info_energywise.php (Last accessed August 16, 2010).

16 NLPIP 2007. Photosensors. National Lighting Product Information Program, Rensselaer 

Polytechnic Institute, Troy, NY. (Last accessed March 24, 2011) <

http://www.lrc.rpi.edu/nlpip/publicationdetails.asp?id=916>

17 The Economics of Dimming, Rowbottom, May 26, 2010.
3-49

 18 National Lighting Product Information Program. Lighting Answers: Electromagnetic 

Interference Involving Fluorescent Lighting Systems. 1995. (Last accessed March 24, 2011). 

<http://www.lrc.rpi.edu/programs/NLPIP/lightinganswers/pdf/view/LAEMI.pdf>.