Wiring Compartments in Explosion-Proof Lights

[mjsadaway]

I'm an engineer new to the forum. I design LED tank lights used in the food, beverage, pharmaceutical, and process industries.

My company is developing new models of our explosion-proof tank lights. These will be UL or ETL listed.

I'm familiar with the applicable UL and CSA standards for designing the lights, less familiar with code requirements and with the preferences of electricians and contractors for installing them.

Some of our current models have separate "wiring compartments" and "lamp enclosures" and some do not. Lights that have separate wiring compartments have UL-required seals between the wiring compartments and the lamp enclosures.

Presumably, when lights with these internal seals are installed using conduit, a conduit seal isn't required where the conduit enters the wiring compartment.

I'm not certain of this because I'm a little confused by the wording of the exceptions listed in NEC 501.15(A)(1), which refer only to a "switch, circuit breaker, fuse, relay, or resistor" and not the other components found in LED lights.

Is it correct that conduit seals aren't required in this case?

If so, is this feature something that you look for or that you prefer?

Or is it just as acceptable to require a separate conduit seal?

Thanks.

Mike

 

[rbalex]

First, welcome to the community.

Second, Ya gotta love English ambiguity and the subsequent wordsmithing of NEC text that often occurs.

Since you are '... familiar with the applicable UL and CSA standards for designing the lights ...', my initial response would be: 'Is your luminaire, "marked "Leads Factory Sealed," or "Factory Sealed," "Seal not Required," or equivalent.'? [NEC 501.15(A)(1)(1) Ex(3)] If it is, you don't need to worry beyond that, i.e., no conduit seal. If not, then a fair amount of field analysis is required - still not your problem.

The actual default considerations are that switches, circuit breakers, fuses, relays, or resistors that may produce arcs, sparks, or temperatures that exceed 80 percent of the autoignition temperature, in degrees Celsius exist in the "wiring compartments" [NEC 501.15(A)(1)(1)] OR the entry is metric designator 53 (trade size 2) or larger, and the enclosure contains terminals, splices, or taps. [NEC 501.15(A)(1)(2)]

 

[mjsadaway]

Thanks for your reply.

I'll have to get used to the NEC writing style. I think they actually do a better job than some of the UL standards committees.

None of our luminaires are marked "Factory Sealed" et al., and neither is one of our competitor's that has a seal.

I think this is because UL 844's extensive marking requirements don't include this provision.

The "Factory Sealed" et al. markings are required by UL 1203, which supposedly doesn't apply to luminaires, since luminaires are covered by a separate standard.

To me, it would make more sense to mark devices that require conduit seals rather than those that don't. Maybe I can find a way to suggest this to UL.

That leaves me with my original concern - designing a product that best meets the needs and preferences of the customer, which in the case of our tank lights is usually a contractor installing them for the end user.

Does it make sense to provide a sealed wiring compartment and mark the light as "Factory Sealed" even though UL 844 doesn't say we can?

 

[Buck Parrish]

Thanks for your reply.

I'll have to get used to the NEC writing style. I think they actually do a better job than some of the UL standards committees.

None of our luminaires are marked "Factory Sealed" et al., and neither is one of our competitor's that has a seal.

I think this is because UL 844's extensive marking requirements don't include this provision.

The "Factory Sealed" et al. markings are required by UL 1203, which supposedly doesn't apply to luminaires, since luminaires are covered by a separate standard.

To me, it would make more sense to mark devices that require conduit seals rather than those that don't. Maybe I can find a way to suggest this to UL.

That leaves me with my original concern - designing a product that best meets the needs and preferences of the customer, which in the case of our tank lights is usually a contractor installing them for the end user.

Does it make sense to provide a sealed wiring compartment and mark the light as "Factory Sealed" even though UL 844 doesn't say we can?

IMO no, because some times we hang them from the conduit and bring the wires right into them.

 

[mjsadaway]

Our lights mount on tanks, so hanging them from conduit isn't an option. But of course this is done.

For example, Crouse-Hinds luminaires for Class I, Div. 1 have explosion-proof wiring compartments that are separated and sealed from the lamp compartments. These are presumably marked "Factory Sealed" or the equivalent, even though UL 844 doesn't mention this possibility, and they are routinely hung from conduit without external conduit seals.

Are you saying that you wouldn't want this feature?

 

[rbalex]

Our lights mount on tanks, so hanging them from conduit isn't an option. But of course this is done.
Are you saying that you wouldn't want this feature?

If it isn't an option, but it is done anyway you have just identified a violation of NEC Section 110.3(B).

UNLESS you can show it conforms with Section 500.8(A)

 

[Buck Parrish]

Our lights mount on tanks, so hanging them from conduit isn't an option. But of course this is done.

For example, Crouse-Hinds luminaires for Class I, Div. 1 have explosion-proof wiring compartments that are separated and sealed from the lamp compartments. These are presumably marked "Factory Sealed" or the equivalent, even though UL 844 doesn't mention this possibility, and they are routinely hung from conduit without external conduit seals.

Are you saying that you wouldn't want this feature?

Yes, I am saying, I would not want that feature.

 

[mjsadaway]

But wouldn't having a "factory seal" eliminate the need for an external conduit or cable seal and make installation simpler and less expensive?

Why wouldn't you want that?