Relamping Hazardous Location Fixtures with CFL's

[al]

Question:

If hazardous location fixtures listed for a C1D1 location with A type incandescent lamps are relamped with CFL's does this negate the hazardous location listing?

 

[GoldDigger]

Given that you have a sealed fixture designed for an incandescent Type A, you may have a hard time finding a screw-in CFL that will not overheat and burn out the driver quickly. (Even if there are no regulatory issues.)
A screw-in LED would be more likely to survive, but would still be problematic.
Your best bet would be a new luminaire designed for FL with a proper heat sink for the electronics.
(IMHO)

Tapatalk...

 

[kwired]

Shouldn't matter to the hazardous location rating, and should run cooler than the incandescent, but as golddigger mentions enclosed CFL's do have heat issues that effect life of the CFL.

 

[GoldDigger]

Shouldn't matter to the hazardous location rating, and should run cooler than the incandescent, but as golddigger mentions enclosed CFL's do have heat issues that effect life of the CFL.

To expand on my original comment somewhat, we can look at the path by which heat leaves the fixture.

The incandescent bulb gets very hot and mostly by convection transfers heat to the air. If the air is very hot, that will still not be a major issue for the life of the bulb.
That heated air transfers heat to the body of the fixture, which moves it by conduction (low temperature differential) to the outside of the fixture, possibly a finned heat sink and from there to the surrounding air.

When you put in the CFL, there is less heat to be rejected, but since the CFL ballast has to transfer heat to the air which then has to transfer heat to the fixture, that air will get a lot hotter than if the CFL were sitting in freely moving ambient air. The fact that the outside of the fixture will be cooler and that the air temperature inside will be lower than with an incanescent, does not do the overheated CFL ballast any good. It is still hotter than it wants to be.

The CFLs that are designed for air tight enclosures (if you can find them) use more expensive components in their electronics that can survive a higher temperature. They do not have any magic way of running cooler in that environment, they are just built to work with it.

 

[rbalex]

Luminaires are a special case in Classified locations; especially in Class I, Division 1. Identification is required for the "complete assembly", including the lamps. See Section 501.130(A)(1). There are a few acceptable "retrofits" but the manufacturer must be consulted.

BTW luminaires "breathe" just like any other enclosure in Class I applications. Well, Zones recognize "restricted breathing" for certain 'Type "n"' protection techniques, but that isn't under discussion here - and they still "breathe".

 

[GoldDigger]

BTW luminaires "breathe" just like any other enclosure in Class I applications. Well, Zones recognize "restricted breathing" for certain 'Type "n"' protection techniques, but that isn't under discussion here - and they still "breathe".

Just to get it clear in my mind, you are using "breathe" to refer to enough air flow to prevent a pressure change from expansion, etc., but not free air flow as would be important for heat transfer?
I guess I should not have been using "sealed" in my description, since that carries a connotation of "pressure tight".

 

[rbalex]

Just to get it clear in my mind, you are using "breathe" to refer to enough air flow to prevent a pressure change from expansion, etc., but not free air flow as would be important for heat transfer?...

Yes, basically. All explosionproof enclosures permit air flow during normal air pressure/temperature changes. It's one of the reasons water condensate may form. It is expected that ignitable vapors will also collect in them and air passages are expected to create a "flame-path" that cools the internal ignited materials to below the AIT of external gases/vapors. "Heat transfer" is typically accomplished by radiation.