NEC wiring requirements for a nonincendive device, in a Class I, Division 2 Location

[DM2-Inc]

Does the wiring to my nonincendive device have to be installed in accordance with 501.10(B)(3)?

501.10(B) addresses wiring requirements and permits the use of conventional junction boxes in 501.10(B)(4) provided 501.105(B)(1), 501.115(B)(1), or 501.150(B)(1) don’t apply. In my case, because the device is nonincendive, the three (3) referenced sections don’t apply.

The device has been tested and approved to ISA 12.12.01 for nonincendive devices. Under the heading “Purpose” in the ISA standard it states:

The purpose of this standard is to provide minimum requirements for the design, construction, and marking of electrical equipment or parts of such equipment for use in Class I and Class II, Division 2 and Class III, Divisions 1 and 2 hazardous (classified) locations. This equipment, in normal operation, is not capable of causing ignition of the surrounding atmosphere under the conditions prescribed in this standard, although the equipment may contain electronic components that operate at incendive levels and may also have field wiring that is incendive. In addition, it is the intent of this document to establish uniformity in test methods for determining the suitability of the equipment and associated circuits and components as they relate to potential ignition of a specific flammable gas or vapour-in-air mixture, combustible dust, easily ignitible fibers, or flyings.​

Because 501.10(B)(3)) starts off with “Nonincendive field wiring shall be permitted…”, and based on the above highlighted section, I’m assuming I don’t have to install the wiring as “nonincendive” per 501.10(B)(3).

Am I missing anything?

 

[rbalex]

Does the wiring to my nonincendive device have to be installed in accordance with 501.10(B)(3)?
...

No, but it would then need to comply with Sections 501.10(B)(1)&(2).

Section 501.10(B)(3) is permissive, not required.

 

[DM2-Inc]

Two of the exceptions in 501.105(B)(1), and 501.150(B)(1) are:
...Are in nonincendive circuits
...Are listed for Division 2

Would a device which is listed as nonincendive, satisfy the exception of "Are in nonincendive circuits", or "Are listed for Division 2", assuming the wiring isn't in accordance with 501.10(B)(3) Nonincendive Field Wiring?

I'm thinking the exception that applies is "Are Listed for Division 2" because the wiring method isn't "nonincendive", even though the device is.

 

[rbalex]

If you review Section 501.150(B)(1) carefully, it doesn't say, "Are listed for Division 2". However, it cross references Section 501.105(B)(1) so it is effectively the same.

I gather you're trying to avoid explosionproof enclosures AND avoid the all hoops you need to jump through to properly install per Section 501.10(B)(3). [NI and IS cause the biggest misunderstanding when it comes to cost effective wiring methods in classified locations]

• A device listed (or ​identified) for Division 2 may be used without an explosionproof enclosure, but the wiring method must still be consistent with Sections 501.10(B)(1) and (2).
• An NI device must either be part of an NI circuit OR enclosed in some manner suitable for Division 2. Explosionproof is simply one method, the other Exceptions in Section 501.105(B) are also acceptable.

You should also review Section 500.8 carefully.

 

[DM2-Inc]

Actually the problem started with the desire by an installer to use form 5, 7, or 8 fittings to make up wiring connections. That issue was corrected.

The hazard is Class I, Division 2, Group B. The GUA type fittings are not approved for Group B, however the devices are hermetically sealed heat detectors , and NI strobes.

I’d prefer to use the GUA type fittings as they’re robust. I’m concluding, because of the above, the fact that they’re not rated for Group B, isn’t an issue.

With respect to 501.105(B), the heat detector complies with exception 2 (hermetically sealed). The circuit connected to the strobe is not installed as NI, exception 3 doesn't apply, but the strobe is NI and suitable for Division 2, which is why I'm thinking Exception 4 applies.

with respect to 500.8(3) would seem to support my belief.

Your opinion?

 

[rbalex]

Have you considered Section 501.10(B)(4) in light of 500.8(C)(6)(a)? Remember, equipment is very broadly defined in Article 100. BTW, identified​ is worth reviewing in Art 100 too.

 

[DM2-Inc]

In my case this box is to make the wiring connections for the HS, and NI device (both of which have wire leads), which might otherwise require a seal.

If I understand your reference to 500.8(C)(6)(a), the argument would be that because 501.10(B)(4) allows the use of any old box, 500.8(C)(6)(a) allows me to ignore the fact that the GUA box has a “Group B” rating?

I did look at "equipment" in 100, which allows a broad interpretation of the word in reference to 500.8(C)(6)(a). I don't see how the term "identified​" helps.

 

[rbalex]

The Form 5, 7 and 8s are fine in Division 2 for non-explosionproof applications. (I prefer 8s, but that is only design preference on my part)

You have already established the enclosures aren't required to be explosionproof - seals aren't necessary. (They're useless on non-explosionproof enclosures anyway)

Section 500.8(C)(6)(a) removes the need to Group B marking - or any other mark unique to classified locations for ordinary location equipment.

Identified does not necessarily mean listed or labeled. See Section 500.8(A) as well.

 

[DM2-Inc]

The Form 5, 7 and 8s are fine in Division 2 for non-explosionproof applications. (I prefer 8s, but that is only design preference on my part)

Form type fittings are UL 514B approved (...raceways...). It's my understanding that you can't make a wire termination in them. Both the heat detector and the strobes have wire leads essentially requiring a box to make a connection in. Have I got that wrong?. I'd expect it to be UL 514A in order to make a wire termination in the box.

 

[rbalex]

The "forms" are conduit bodies. See Section 314.16(C)(2).