8D-i

APPENDIX 8D. HOT SHOCK IN INCANDESCENT REFLECTOR LAMPS 

TABLE OF CONTENTS 

8D.1 INTRODUCTION AND PURPOSE ...................................................................... 8D-1

8D.2 IMPACT OF STANDARDS .................................................................................. 8D-2

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

LIST OF FIGURES 

Figure 8D.1.1 Filament after Hot Shock; Shorted Coils Visible .............................................. 8D-2

LIST OF TABLES 

Table 8D.2.1 IRL Lifetime Reduction at CSL 1 ....................................................................... 8D-2
8D-1

APPENDIX 8D. HOT SHOCK IN INCANDESCENT REFLECTOR LAMPS 

8D.1 INTRODUCTION AND PURPOSE 

 Incandescent reflector lamps (IRLs) 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. IRLs 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. The coiled structure of the filament brings it in close proximity with other 

parts of itself and external forces to the lamp 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 a 

shorted circuit and produces a higher temperature that subsequently reduces the life of the lamp. 

This phenomenon is known as hot shock. Figure 8D.1.1 shows an image of a filament that has

experienced hot shock; the darkened regions are where the coils have been shorted. While certain

kinds of IRLs contain filament supports to reduce the probability of hot shock, halogen and HIR

capsules do not contain such supports because they would reduce lamp efficacy.1

 Hot shock can occur when an IRL is installed into an electrical socket that is active, 

which causes electricity to flow through the lamp before it is completely seated by the installer.2

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

shock in IRLs is to deactivate the electrical socket during lamp installation or during lamp 

position adjustments on movable fixtures (such as movable spotlights). If the electrical 

connection cannot be deactivated, then the lamps should be installed or moved as smoothly and 

carefully as possible to reduce the risk of hot shock. 

 Because lamp lifetime impacts the life-cycle cost (LCC) analysis and hot shock shortens 

the lifetime of IRLs, the U.S. Department of Energy (DOE) evaluated the possible impacts of hot 

shock on potential standards. 

 
8D-2

Figure 8D.1.1 Filament after Hot Shock; Shorted Coils Visible3

8D.2 IMPACT OF STANDARDS 

 DOE analyzed the impacts of standards at the candidate standard level (CSL) considered 

for IRLs with respect to shortened lifetime as a result of hot shock. Because the LCC of a 

product depends directly on the product lifetime, the occurrence of hot shock in an IRL will 

impact the LCC savings to the consumer. Switching to a more efficacious IRL that operates for a 

longer time will result in an increase in the residual value of the lamp, delivering greater LCC 

savings to the consumer. Therefore, DOE performed an analysis to determine how much the 

lifetime of IRLs at CSL 1 could be shortened before it negatively impacted LCC savings. 

 As discussed in chapter 5 of this preliminary technical support document (TSD), DOE 

evaluated two baselines for IRLs, a 1,500-hour improved halogen lamp and a 3,000-hour 

halogen-infrared (HIR) lamp. To obtain minimum lifetime values, DOE reduced the lifetime of 

lamps at CSL 1 for all scenarios with positive LCC savings until those savings became negative. 

The results of this analysis are shown in Table 8D.2.1. IRL lifetime could be shortened by 48 

percent in the commercial sector and 43 percent in the residential sector before the consumer 

experiences negative LCC savings at CSL 1 relative to the 1,500-hour improved halogen 

baseline. Note that the LCC results for the 3,000-hour HIR baseline were negative and thus were 

not included in the hot shock analysis; this is indicated by “N/A” in the table below. 

Table 8D.2.1 IRL Lifetime Reduction at CSL 1 

Baseline

Commercial Sector Residential Sector

Lifetime

(hours)

Percent 

Reduction

Lifetime

(hours)

Percent 

Reduction

60 W PAR38 1,500 hour

Improved Halogen 2,302 48% 2,509 43%

60 W PAR38 3,000 hour HIR N/A N/A N/A N/A
8D-3

REFERENCES 

1 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. 

2 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. 

3 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.