8D-i

APPENDIX 8D. HOT SHOCK IN INCANDESCENT REFLECTOR LAMPS 

TABLE OF CONTENTS 

8D.1 INTRODUCTION AND DEFINITION................................................................. 8D-1

8D.2 IMPACT OF HOT SHOCK ON LIFE-CYCLE COST SAVINGS ....................... 8D-1

8D.3 AVOIDING HOT SHOCK..................................................................................... 8D-2

REFERENCES ......................................................................................................................... 8D-3

LIST OF FIGURES 

Figure 8D.1 Filament After Hot Shock; Shorted Coils Visible................................................ 8D-1

LIST OF TABLES 

Table 8D.1 Commercial-Sector IRL Lifetime Reduction for Negative LCC Savings............. 8D-2

Table 8D.2 Residential-Sector IRL Lifetime Reduction for Negative LCC Savings............... 8D-2
APPENDIX 8D. HOT SHOCK IN INCANDESCENT REFLECTOR LAMPS 

8D.1 INTRODUCTION AND DEFINITION 

 Incandescent reflector lamps (IRL) produce light when a thin tungsten wire (filament) 

inside the lamp is heated to a temperature high enough to cause incandescence, which is the 

production of electromagnetic energy in the visible spectrum due to the movement of hightemperature molecules. Incandescent reflector lamps that feature halogen or halogen-infrared 

(HIR) technologies incorporate a filament that is contained within a small capsule inside of the 

lamp. In order for the filament to fit inside of the capsule while being of the necessary length to 

allow the lamp to obtain its rated performance, the filament must be coiled upon itself. 

 Because the filament is thin, it is subject to movement due to forces (such as sudden jolts) 

applied to the lamp. Because the filament is also coiled (bringing the filament into close 

proximity with other parts of itself), movements of the filament due to external forces can cause 

parts of the filament to touch each other. If this self-contact occurs when the filament is heated 

and producing light, the areas that contact each other can weld together and cause an electrical 

short. Electrical current is higher through the short, producing a higher temperature that 

subsequently reduces the life of the lamp. This phenomenon is known as hot shock. Figure 8D.1

shows an image of a filament that has experienced hot shock; note the darkened region where 

coils have been shorted. While certain kinds of IRL contain filament supports to reduce the 

probability of hot shock, halogen and HIR capsules do not contain such supports because they 

would reduce efficacy.i

 

Figure 8D.1 Filament After Hot Shock; Shorted Coils Visibleii

8D.2 IMPACT OF HOT SHOCK ON LIFE-CYCLE COST SAVINGS 

 Because the life-cycle cost (LCC) of a product depends directly on the product lifetime, 

hot shock in an incandescent reflector lamp will impact the life-cycle cost. The LCC savings 

that a consumer can achieve when switching to a more-efficient IRL thus also depends on the 

effective lifetime of that more-efficient lamp; a more-efficient product will incur more operating 

cost savings and thus deliver greater LCC savings to the consumer if it operates for a longer 

8D-1
8D-2

time. The U.S. Department of Energy (DOE) thus attempted to determine the minimum lifetime 

the IRL analyzed in Chapter 8 (life-cycle cost and payback period analysis) must have in order to 

deliver positive LCC savings to the consumer. To obtain these minimum lifetime values, DOE 

utilized the LCC spreadsheet described in Appendix 8A and reduced the lifetimes of all lamps 

with positive LCC savings until those LCC savings became negative. The results of this analysis 

are shown in Table 8D.1 for the commercial sector and in Table 8D.2 for the residential sector. 

The percent reduction column shows the percent reduction in IRL lifetime that would have to 

occur (due to hot shock or other causes) before the consumer experiences negative LCC savings. 

Note that some lamps analyzed by DOE gave negative LCC savings to consumers even when 

operated for their full rated lifetimes; these lamps are indicated by “N/A” in the tables. 

Table 8D.1 Commercial-Sector IRL Lifetime Reduction for Negative LCC Savings 

90W Baseline 75W Baseline 50W Baseline 

Efficacy Level Lifetime 

Percent 

Reduction Lifetime 

Percent 

Reduction Lifetime 

Percent 

Reduction 

EL1 N/A N/A N/A N/A N/A N/A 

EL2 - 6,000 hr 2587 57% 2587 57% 3277 45% 

EL2 - 3,000 hr 2242 25% 2242 25% N/A N/A 

EL3 1897 37% 1897 37% 2932 2% 

EL4 - Short-life 1897 24% 2242 10% N/A N/A 

EL4 1897 53% 2242 44% 3277 18% 

EL5 - Short-life 1897 24% 1897 24% N/A N/A 

EL5 1897 55% 1897 55% 3277 22% 

Table 8D.2 Residential-Sector IRL Lifetime Reduction for Negative LCC Savings 

90W Baseline 75W Baseline 50W Baseline 

Efficacy Level Lifetime 

Percent 

Reduction Lifetime 

Percent 

Reduction Lifetime 

Percent 

Reduction 

EL1 2443 2% N/A N/A N/A N/A 

EL2 - 6,000 hr 2355 61% 2532 58% 3233 46% 

EL2 - 3,000 hr 1999 33% 2177 27% 2977 1% 

EL3 1644 45% 1821 39% 2621 13% 

EL4 - Short-life 1733 31% 1910 24% 2977 1% 

EL4 1733 57% 1910 52% 2977 26% 

EL5 - Short-life 1644 34% 1910 24% N/A N/A 

EL5 1644 61% 1910 55% 3243 23% 

8D.3 AVOIDING HOT SHOCK 

Hot shock can occur when an IRL is installed into an electrical grid or socket that is 

active, which causes electricity to flow through the lamp before it is completely seated by the 

installer.iii Hot shock can also occur during the movement of active lamps. Thus, one way to 

avoid hot shock in IRL is to deactivate the electrical grid or socket during lamp installation or 

during the aiming of lamps on movable fixtures (such as movable spotlights). If the electrical 

connection cannot be de-activated, then the lamps should be installed or moved as smoothly and 

carefully as possible to reduce the risk of hot shock. 
8D-3

 

REFERENCES 

i

 GE Consumer & Industrial Lighting. 2009. No. 63, Appendix 5 at p. 1. This attachment to a 

written comment, Document Number 63 Appendix 5, is available in Docket #EE–2006–STD–

0131. For more information, contact Brenda Edwards-Jones at (202) 586-2945. 

ii National Electrical Manufacturers Association. 2009. No. 81 at p. 27. This written comment, 

Document Number 81, is available in Docket #EE–2006–STD–0131. For more information, 

contact Brenda Edwards-Jones at (202) 586-2945. 

iii GE Consumer & Industrial Lighting. 2009. No. 63, Appendix 5 at p. 1. This attachment to a 

written comment, Document Number 63 Appendix 5, is available in Docket #EE–2006–STD–

0131. For more information, contact Brenda Edwards-Jones at (202) 586-2945.