Class 1 Div II Group D lighting installation

[Mbob]

We are budgeting a large class 1 div II group D lighting project. I have found some class 1 div II group D fixtures that have some brackets they can be mounted to the purlins with rather than using threaded RMC or IMC. The local inspector agrees these are an approved means. My question is per 501.10 B 4 can we use standard 4" square boxes for splicing with flex or sealtite whip to the light fixtures? Are we required to use bonding locknuts on the IMC and flex or sealtite per 250.100 which refers us to 250.92 B 2-4 even with an equipment grounding conductor in the raceway and bonding the box?

thx

 

[rbalex]

... My question is per 501.10 B 4 can we use standard 4" square boxes for splicing with flex or sealtite whip to the light fixtures? ...

Yes - but I don't recommend it.

... Are we required to use bonding locknuts on the IMC and flex or sealtite per 250.100 which refers us to 250.92 B 2-4 even with an equipment grounding conductor in the raceway and bonding the box?

Yes.

Actually, bonding locknuts may not be sufficient. In general, CMP 14 wants a minimum of five(5) threads or a bonding system that eliminates/reduces possible circulating stray currents (not necessarily "ground" currents) from arcing at joints. See Sections 500.8(E) as well as 501.30(A). Note the bonding requirements in all Classes and Divisions is virtually identical.

Personally, I'd recommend simple threaded conduit bodies.

 

[Mbob]

Thanks...I think I will figure T fittings as you mentioned. One more quick question 501.10 B 2 mentions liquidtight flexible conduit with listed fittings. By listed are they meaning UL listed or is there another listing for the liquidtight connector for a class 1 div II location?

 

[rbalex]

Thanks...I think I will figure T fittings as you mentioned. One more quick question 501.10 B 2 mentions liquidtight flexible conduit with listed fittings. By listed are they meaning UL listed or is there another listing for the liquidtight connector for a class 1 div II location?

Actually this has become somewhat moot since the NEC now requires all Chapter 3 raceways and their fittings to be listed. See Section 350.6, for example. This and Section 110.3(B) will simply require that the fittings are listed for use with LFMC. No special Class I, Division 2 identification (marking) is required.

While UL is the most common listing agency for this type of equipment, it isn't exclusive.

BTW my pet peeve: "Class" uses Roman numerals, "Division" uses Arabic. It's just a pet peeve though; I know what you mean. It bothers me more when a manufacturer confuses them.