Wirenuts in Classified Area 4

[controlnovice]

We have a NEMA4 junction box in a Class I, Div 2 area. The equipment inside is rated for Class I, Div 2. The wires coming in are connected via wirenuts.

Are wirenuts acceptable in Class I, Div 2 areas??? I'd rather see a terminal block. I can find terminals rated for Ex locations (Cenelec - maybe ATEX now?). Does the terminal block have to be rated for Class I, Div 2 in a NEMA4 j-box?

 

[ScottyUK]

I'm no hazardous areas expert, but you appear to be mixing European and North American terminology. Which standard are you designing to?





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If we learn from our mistakes,
I'm getting a great education!

 

[controlnovice]

Yes. A slight mixing - but acceptable in the States with the following disclaimer.

Certain Ex equipment can be located in Class I, Div 2 areas. It does have to be labeled for NEC AEx.

I can't find anything that talks about wirenuts. I'm not comfortable with them in hazardous areas. Was just looking for information (ammo).

 

[peebee]

Wirenuts in Div 2 are OK. Matter of fact, you could make a splice inside a Home Depot handy box by twisting the wires together and wrapping with electrical tape and still be in compliance with Class I Div 2 requirements. See NEC 501.3(B), 501.4(B), 501.6(B), 501.14(B), and particularly 501.4(B)(4).

In Div 2, you don't even need an XP box UNLESS you are enclosing an arcing device such as a switch, breaker, relay, horn, or bell, or a few other devices such as meters and resistors. Splices are not considered arcing devices per NEC. Note that not even transformers or motors require XP enclosures UNLESS they contain arcing devices. Also note that while the handy box is OK, a sealing fitting CANNOT be used for splices per 501.5(C)(4).

By the way, wirenuts are also OK in Div 1 areas. But in Div 1, you can't use the Home Depot handy box since all Div 1 boxes are required to be XP rated per 501.4(A)(3).

 

[peebee]

Re "Does the terminal block have to be rated for Class I, Div 2 in a NEMA4 j-box?" -- there's no such thing. . . unles you install the terminal block in an XP rated box, and then stick THAT inside the NEMA 4 box.

You do realize that NEMA 4 is NOT an XP rated box, right? NEMA 4 is related to protection against washdown and rain, but has essentially no relevance to XP installations.

XP boxes include NEMA 7, 8, & 9.

 

[controlnovice]

Yes, I know the different NEMA ratings. Just wasn't sure about terminations inside them.

Thanks for the answer. Finally someone who knows how to answer a question directly!!!!

 

[jsummerfield]

One issue may be whether or not wire nuts violate code. Another issue is whether or not they should be used.

You will not use wire nuts on my projects.

John

 

[controlnovice]

I also agree. Even if it is acceptable, I didn't feel comfortable using them.

 

[peebee]

So, you two don't use any wirenuts in any XP areas?

Just curious -- do you provide terminal blocks at every light fixture, motor, etc.?

Or do you feel wirenuts are OK in XP boxes?

 

[peebee]

Oops -- two more associated questions -- are all your boxes in Div 2 areas XP rated?

And finally, if you put wirenuts in the XP boxes, do you provide seals at the boxes too?

 

[jsummerfield]

I avoid wire nuts for industrial applications. I use them at home where required.

Typically division 2 junction boxes are NEMA 4X. Offshore I find that the plastic enclosures hold up better than stainless.

Many standard pressure switches, etc. are available with pigtails; terminals are a costly option. I buy the option.

I am less certain what we get regarding motors and lights. I think that the motors terminate with lugs.


John

 

[peebee]

Re "I avoid wire nuts for industrial applications. I use them at home where required." -- Just to get slightly off-topic, taking this outside of the XP arena. . .

I used to work for a consulting A/E firm where the standard for all installations (mostly non-XP, light-medium commercial) was crimp-on connectors, the ones that look like wirenuts but have a metal barrel in a plastic cover rather than a spring. This was their standard because they felt they were more reliable. I never liked them for 2 reasons:
1) the pigtails get shorter every time you make a change, and
2) I'm not that sure that these connectors are any more reliable than wirenuts UNLESS you give a good tug on them after the crimp to make sure that they actually stay on. . . .

jsummerfield -- are you typically using t-blocks, crimp-ons, or something else in these industrial applications?

 

[jsummerfield]

Most instrumentation wiring terminates on DIN rail mounted terminal blocks. These include the clamp type typical of Weidmuller/Phoenix/Entralec, etc. and recently more of the spring-loaded blocks like Wago.

John

 

[peebee]

Re "Most instrumentation wiring terminates on DIN rail mounted terminal blocks." -- no doubt -- but that's true even in GP areas.

 

[hacksaw]

you should not be using wire nuts in any industrial environment. reliability and documentation are just some if the issues.

terminal blocks in a suitable enclosure are recommended.

 

[peebee]

Re "you should not be using wire nuts in any industrial environment" -- again, please clarify that statement. Are you talking NO wirenuts for ANY wiring anywhere (including lighting, receptacles, fractional horsepower motors, etc), or are you speaking only to instrumentation wiring?

The use of terminal blocks to splice to a GP fluorescent ballast seems like maybe just a bit of overkill now, doesn't it?

I don't see anything anywhere in this thread which is limiting the discussion to instrumentation wiring. So be careful about broad generalizations here. In my opinion, there are plenty of XP industrial applications where wirenuts are perfectly suitable. Maybe not for instrumentation -- but plenty of power & lighting applications.

 

[hacksaw]

many industrial plants do not allow wire nuts or splices that is a broad statement but broadly encountered.

are they used in light industry or commercial establishments, yes commonly so. but personally encountered one wire nut failures that was at the point of causing a fire. that was a real eye opener. they are not a secure means for termination.

do not know if the actual failure rates of WN's but it would be nearly impossible to "standardize".

 

[rbalex]

While they haven't been tested for it, I believe "live - spring" with square cross-section spring wire connectors would meet most Exe requirements.

In general, other twist on type connectors are acceptable in Division 2 where they would be acceptable in the same "ordinary location" application. They are not considered to be inherently, arcing, sparking or heat producing. Lighting circuits is a fairly common application.

 

[peebee]

rbalex -- when you say "acceptable" -- do you mean to an AHJ? I do not believe there is any code that prohibits the use of wirenuts in Class I (correct me if I'm wrong), so I don't see why they wouldn't be acceptable too.

Or, do you mean "acceptable to rbalex" or "acceptable in my company" or "accpetable in my industry"?

I've seen plenty of wirenuts installed in Class I areas in pharmaceuticial & chemical plants. The plants, and their AHJ's, all thought they were acceptable. So do I.

Everyone, please note that there's a BIG difference between "not acceptable" and "not my company's standard" and "I personally don't like them".

 

[peebee]

I still haven't seen this one answered yet, either:

If you're not using wirenuts for your lighting circuits, then what ARE you using?