EXPOSED THHN in NEMA Enclosures

[magic_garage]

Hi:

I was helping out a friend with some various things at a local pre-school and I noticed the school had an outdoor enclosure installed to house some network equipment mounted outside of a building. In the enclosure, I noticed a 120VAC receptacle in a weatherproof outlet box mounted to the back panel of the enclosure. I also noticed that from the penetration of the enclosure to the receptacle outlet box, the THHN wires ran unprotected for a few inches (~4"). I wanted to know if this exposed THHN is to code or not, and if not, what's the correct method?

Here's some additional info. The enclosure was a stainless steel enclosure, and the THHN wires came in via a rigid conduit. The receptacle was in a weatherproof outlet box with a cord grip thingy. The receptacle was NOT GFCI but I don't know what breaker type it was either since I didn't see the panel for this outlet. I tried searching here and the web but could not find anything conclusive and I don't recall finding anything with the same scenario. To further expand on my question, extending the scenario to all types of enclosures (Type 1 - 12) is the exposed wiring allowed? And when it comes to this Type 4X (my guess) enclosure, I don't see how you would keep the THHN in full conduit and maintain the 4X rating.

Sorry I didn't take a pic, I thought I would easily find this scenario.


Thanks in advance.

 

[Firebrick43]

First THHN isn’t allowed outside typically, needs to be THWN but some wires are dual rated(THWN-2)

No THHN wire are not allowed to be outside the enclosure or conduit for even an inch.

There should have been some kind of weatherproof raceway and/or raceway fittings to attach the outlet box.

 

[wyliesdiesels]

Not code permissible.

Shouldve been in some type of conduit. LT probably easiest…

 

[mm08822]

The receptacle is mounted on the mounting panel within the enclosure. "In the enclosure, I noticed a 120VAC receptacle in a weatherproof outlet box...."

Once the conductors are within the enclosure, the electrical enclosure is the protection for the conductors. There are lots of ways to add further protection and organization to conductors within an enclosure. Real control panels typically use wireway, spiral wrap, etc.

The few inches of "exposed conductors" is a non-issue as long as the enclosure remains uused for electrical purposes.
When it starts becoming a tool box or lunch box that could change things.

The real hazard was eliminated by securing the receptacle in the wp box and providing protection from the receptacle connections.

Taking the cover off of your main panel at home has much more risk!

 

[Firebrick43]

I am confused. Op said the outlet was in the panel but then says “exposed wires” which I took to mean the outlet was mounted to the back(outside) of the panel and the wire exited said panel thru a cord grip.

If everything is inside a panel then there are no exposed wires?



AC conductors you can see once the panel is opened describes probably 98 percent of the panels out there?

 

[micromind]

I am confused. Op said the outlet was in the panel but then says “exposed wires” which I took to mean the outlet was mounted to the back(outside) of the panel and the wire exited said panel thru a cord grip.

If everything is inside a panel then there are no exposed wires?



AC conductors you can see once the panel is opened describes probably 98 percent of the panels out there?

Every one I've ever built looks like that one. Even 480 exposed like that is ok.

It's fairly common to run conduit to some sort of a box and leave the wires exposed inside the box and run them into an outlet box and install a receptacle in that box.

One thing to look out for is where the wires enter the outlet box, is there some sort of a plastic bushing or do they just go into an open hole with no protection from sharp edges? Very common mistake.

 

[magic_garage]

I am confused. Op said the outlet was in the panel but then says “exposed wires” which I took to mean the outlet was mounted to the back(outside) of the panel and the wire exited said panel thru a cord grip.

If everything is inside a panel then there are no exposed wires?



AC conductors you can see once the panel is opened describes probably 98 percent of the panels out there?

Thanks, this is the scenario.

 

[magic_garage]

First THHN isn’t allowed outside typically, needs to be THWN but some wires are dual rated(THWN-2)

No THHN wire are not allowed to be outside the enclosure or conduit for even an inch.

There should have been some kind of weatherproof raceway and/or raceway fittings to attach the outlet box.

I meant THHN/THWN.

 

[magic_garage]

Thanks everyone. What was inconclusive to me was the NEC mentioned the conductors not allowed to be in open air and I didn't quite know what to consider the air space in a Type 1 - 12 enclosure to be.

Not sure if I need another thread for this, but what type of enclosure would NOT be allowed to have the wires "exposed"? You have telecom cabinets which could be argued that is similar (to me at least) to the other said enclosures. But that would seem pretty dangerous to have the THHN/THWN exposed in those cabinets?

 

[Stuart in MN]

It can be confusing, there are different codes involved. Industrial control panels are typically built to meet UL508A. I believe there are other requirements that are specific for telecom cabinets. In any case, their construction requires some knowledge of the specific sections of the the NFPA and UL code books.