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Wirenuts in Classified Area
4

Wirenuts in Classified Area

Wirenuts in Classified Area

(OP)
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?

RE: Wirenuts in Classified Area

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!

RE: Wirenuts in Classified Area

(OP)
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).

RE: Wirenuts in Classified Area

2
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).

RE: Wirenuts in Classified Area

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.  

RE: Wirenuts in Classified Area

(OP)
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!!!!

RE: Wirenuts in Classified Area

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

RE: Wirenuts in Classified Area

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

RE: Wirenuts in Classified Area

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?

RE: Wirenuts in Classified Area

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?

RE: Wirenuts in Classified Area

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

RE: Wirenuts in Classified Area

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?

RE: Wirenuts in Classified Area

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

RE: Wirenuts in Classified Area

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

RE: Wirenuts in Classified Area

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.

RE: Wirenuts in Classified Area

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.

RE: Wirenuts in Classified Area

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".

RE: Wirenuts in Classified Area

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.

RE: Wirenuts in Classified Area

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".

RE: Wirenuts in Classified Area

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?

RE: Wirenuts in Classified Area

peebee,

all of the above - as you said they are not prohibited in US domestic work.

The original question was:
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?

"Twist on" type connectors are acceptable in non-explosionproof enclosures in Division 2 per 501.4(B)(4) and they are acceptable in NEC Zone 2 per 505.20(C) Ex 3. They are NOT acceptable in IEC/CENELEC "Zones" unless they are in an Exd (flameproof) enclosure. IEC considers non-Exe connectors to be arc-making; the NEC doesn't. This is one of the few places the IEC hazardous location standards are more restrictive than tne NEC.

In Europe, it is common practice to terminate all wiring in classified locations(including lighting) on Exe terminal blocks.

RE: Wirenuts in Classified Area


I have to agree with rbalex.

The NEC only covers minimum requirements not necessarily what is safe for a particular environment.

Terminal boxes in Div 2 areas are a subject of contention. The assumption is that the person opening them is exercising due caution and an assumption that they are properly closed up.

RE: Wirenuts in Classified Area

Wirenuts(R) are acceptable but the Consumer Product Safety Commission says the Scotchloks(R) are the superior device. They also say that the wire strands have to be cleaned with #220 or #240 silicon carbide abrasive paper. Cleaning the wire strands is the Old Signal Corps method of preventing open circuits and fires. #800 acceptable (my opinion) for fine stranded wire. They also say that you should be using electrical joint compound such as Burndy Penetrox(R) E for copper wire and Penetrox(R) A or A13 for aluminum wire. The latter 2 compounds also for aluminum conduit threads and galvanized steel conduit threads.

One of the other Old Signal Corps specifications was that Wirenuts(R) and Scotchloks(R) have to be taped to that vibration and handling will not unravel the connection and so that a deenergized wire connot poke into something that is energized. Someone tried to tell me that taping a wirenet(R) was a sign of a bad electrician and told him that he never got his fingers burned by a loose wirenut.

Mike Cole, mc5w@earthlink.net

RE: Wirenuts in Classified Area

mc5w -- interesting post.

Can you clarify if those statements are applicable to general-purpose installations, or if they are specific to XP installations?

I've never heard of the CPSC being referenced in context to construction requirments before, I never realized they issued codes/standards/guidelines which might be applicable.

Any thoughts on CPSC jurisdiction?  What are these, nice ideas or mandatory requirements, or somewhere in between?

I'm going to go out on a limb and suggest that almost nobody uses sandpaper or joint compound on copper wires, nor do they tape the wirenuts.  Any thoughts on that?

Not trying to argue with you here, just explore a bit and get a better understanding.

RE: Wirenuts in Classified Area

I'm aware of such a CSPC position paper with regard to aluminum house wiring: http://www.cpsc.gov/cpscpub/pubs/516.pdf
In absence of some local adoption, I doubt it is enforceable.

As a general statement: there is no NEC basis for prohibiting "twist on" type wire connectors in Class I locations, Division or Zone - period. There may be additional requirements under 501.5(A)(1)(2) or 505.16(B)(2)(a)(2), but ANY form of "...terminals, splices, or taps" would be similarly affected; "twist on" connectors have no unique restrictions.

RE: Wirenuts in Classified Area

There should be a certification number on the j-box. The cert. will specify the type of connections, the number of connections etc. There will be a power callculation for the box which will determine how many cables can be terminated dependent on the load.Ref to IEC 61241 IEC 60079 ANZ 2381/2380

RE: Wirenuts in Classified Area

Sort of off topic but this discussion line reminded me of this...

I had a former co-worker who used to be an electrician in Hungary.  He said that when he came to the USA, he got a job as an electrician.  He said that when he first saw the use of wirenuts that he wondered what kind of idiot would use a "f*****g plastic cap" for an electrical connection.


RE: Wirenuts in Classified Area

Wirenuts in classified areas are acceptable per the NEC, but the customer's spec's may not permit them.

Wirenuts are no different than any other termination.  They need to be installed correctly.

How many times have you found a loose wire under a terminal, or loose strands of wire from one terminal making contact with the terminal next to it.

Another option is the "push-in" style terminals that WAGO and everyone else has. I've only used them on one project and haven't got a warm and fuzzy feeling for them yet.

RE: Wirenuts in Classified Area

One of the production lines where I work was plagued by loose connections and wire whiskers with screw type terminals.  They switched to the cage clamp style like Wago, which solved the problem.

I have heard that there used to be problems with this style of connector, though I get the impression that these problems have been solved in modern varients.

RE: Wirenuts in Classified Area

In regards to the question I have used wirenuts in div 1 class 1 locations in the appropriate rated boxes.It is not a NEC violation to the best of my knowledge.I also have had to troubleshoot control wiring and power wiring with wirenuts and terminal blocks problems.A lot of wiring problems could be attributed to one cause HUMANS INSTALLING THEM regardless of wiring method.In my experience noalox/penetrox and taping of wirenuts would eliminate some problems or at least delay them in extreme enviroments.Terminal blocks our prone to the same corrosion problems and are not solved as easily as joint compound and black tape.

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