NEC Code and 'Control Panel Benchboards'

Hi all,

We have some control panel bench-boards, built in the mid 1980's. The front is about 8 ft high and 30 ft wide with an assortment of controls and such. They are totally enclosed with access doors on the back (that are *not* lockable).

All the power/circuits going in/out are in conduit or armored cable. But *inside* the panel, the wiring between terminal boards and components is just single conductor or paired conductor wiring of appropriate size, routed neatly in trays and harnesses.

Also *inside*, are some simple duplex receptacles (standard, 3-prong,

120V). On the drawings, these are labeled simply, 'convenience receptacles' for maintenance personnel when working in the panel. They have a pair of 12 gauge wires (twisted pair) for the hot and neutral, and a separate 12 gauge wire tied to the frame ground bus-bar in the panel (the frame ground is 1/4 x 2 copper bar that runs the length of the panel, and is tied to building grounding with large copper strand).

So, along comes an OSHA inspector who says, "Since that is a 120V receptacle, the feed to it must be in conduit as per NEC for all commercial buildings." And he promptly quotes the paragraph for receptacle outlets used in building wiring. He seems to think that since the wires are single conductor, there is some sort of increased risk that the user could come in contact with a frayed wire feeding the receptacle (never-mind all the other wires and terminals inside the panel!!!)

I'm trying to argue that when this panel was built, it supposedly was built to all codes, and the wiring *inside* the panel is not 'building wiring' that needs to be encased in separate conduit. I thought the reason for armor/thin-wall was to protect the wiring inside walls/floors from damage because you can't see exactly where they are. Like when a carpenter drives in a nail or plumber drills a hole for pipe. These wires, inside the panel, are protected by the panel itself, right?

The OSHA inspector didn't think the other 120V and 208V wiring in the panel was a problem, just the wiring to the receptacles.

Any thoughts/opinions about the receptacle wiring? Do we need to go back and re-wire those specific circuits, even inside this bench-board / panel with armored cable or thin-wall conduit?

Thanks for any constructive comments, I could use a citation or something to get this guy off my back (he's not a master electrician, nor EE, just some guy with a copy of NEC and OSHA safety regs).

daestrom P.S. Considering all the other wiring *inside* I don't see the point, but some OSHA inspector seems to think it makes a difference.

P.P.S. Forgot to also mention that all the receptacle circuits are protected by 15A GFCI's

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He is just nuts. You could run those receptacle circuits with MC cable and put it in a box to shut him up but he is wrong. I have seen these convenience outlets run with SOJ cord inside machines, just to make it look better to over officious jerks..

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  1. There is no such article in the NEC that requires receptacle feeds to be in conduit.
  2. In the case of a factory assembled enclosure, the NEC does not apply. The NEC only applies to the branch circuit running from the breaker panel to the enclosure.
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Article 409 of the NEC covers industrial control panels and the wiring contained in them. It has no references to "convenience outlets", but these have been used inside control panels for decades. Their use is for supplementary lighting, test equipment, and small tools. The panels are not required to be listed. There is no mention of "convenience outlets" in the code, but if they provide power to equipment in the panel they could be considered "disconnects". On the other hand, it they are for maintenance purposes, then the fact that they are enclosed in a panel means that they are not readily accessible, thus not subject to the same wiring rules as building receptacles.

Try labeling them as "For panel maintenace only" and see if that helps...


Reply to
Eric Tappert

Article 409 is relatively new and did not exist when the "bench- boards" were made in the 1980s and wouldn't apply to the installation.

But you could say it does or doesn't apply whichever works out for your argument.

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D If I remember right, you worked in generation - utility?

NEC 90.2 covers what the NEC does, and does not, apply to. quote

90.2 Scope (A) Covered ... for the following: ... (4) Installations used by the electric utility such as office buildings, ... that are not an integral part of a generating plant, substation, or control center.

(B) Not Covered. This Code does not cover the following: ... (5) Installations under the exclusive control of an electric utility where such installations ... b. Are on property owned or leased by the electric utility for the purpose of communications, metering, generation, control, transformation, transmission, or distribution of electric energy, or [c and d. - other utility controlled locations] end quote.

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D If utility, is there a utility electrical engineer that can say the receptacle wiring is safe? (Same for non-utility?)

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D If the boards are listed by UL or equivalent (as in gfretwell's post), that agency would cover what is inside the equipment, which may be

*very* different rules from the NEC. This is explicitly covered in NEC 90.7 for listed equipment.

As Rich wrote, the NEC applies to wiring to the equipment, not wiring inside. (If the boards are not listed/labeled, or equivalent, this argument may not work.)

Is there a manufacturer name? Manufacturer comments?

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D Was there a permit and was the installation inspected? Why would OSHA disagree with the inspector? (Utilities may not need inspection.)

Would converting the receptacles to an odd configuration, like twist lock, make the inspector happy?

It may not matter that the access doors are not lockable if the equipment is only accessible by "qualified" personnel.

-- bud--

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random name

He is really having the problem with OSHA, not the electrical inspector so the NEC may not actually apply.

The NRTL will be the out if he can come up with a listing mark since it is OSHA that certifies NRTLs the US.

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But the OSHA inspector is applying the NEC to the "bench-boards".

Another point of attack is whether OSHA can enforces the NEC. There is a problem in that the NEC changes every 3 years and OSHA does not move fast enough to add the new version of the NEC in a timely manner. At one time I think they were enforcing an old version of the NEC. I thought now they just enforcing general NEC principles. What OSHA reg allows the OSHA inspector to apply the NEC as he is trying to do? It is an argument for deferring to the electrical inspector if this was permitted and inspected.

I agree that if the boards are listed/labeled the inspector is real likely to back off. My guess is they are an exotic application and not likely to be listed. And if this is an electric utility application where the NEC is not applicable they are even less likely to be listed/ labeled.

OSHA certifies NRTLs (Nationally Recognized Testing Laboratories) for OSHA.

-- bud--

Reply to
random name

Thanks for all the above, good info that I'll mull over.

The benchboards were custom built by a manufacturer, so they are not a commercial-off-the-shelf type of panel and hence not U/L listed.

The original contract (took some digging to find), stated they were built to NEC 1978 (current at the time) regarding the wiring to/from the panel (raised floor, so everything is in conduit/armor cable going in/out). But again, we couldn't find anything that would require conduit inside the panels.

The opinion of one local inspector is that "If they were part of the panel as supplied by the manufacturer, fine. But if you add new ones yourself after installation, they would need conduit/armor." Since these are all original equipment, that would be okay by us. But we can't find anything like that in writing.


Reply to




UL has an app ... er... standard for that. It is UL508A - Industrial Control Panels. It covers, among other things, one-of products. UL508A might not have been around in 1980. (I would be surprised if the boards are listed.)

I agree with you and everyone else but the troll that what is there is reasonable. You have an excellent argument that the wiring for the receptacles is as safe as other wiring in the boards. And other people have said that the receptacle wiring is common for the type of panel you have. Its construction likely meets "industry standards". That is probably all you needed in 1980.

And it is a manufactured product. Do you need conduit inside an outlet strip?

The following are in the NEC to guide an electrical inspector that enforces the NEC

(referenced previously) quote

90.7 Examination of equipment for safety. .... It is the intent of this Code that factory-installed internal wiring or the construction of equipment need not be inspected at the time of installation of the equipment, except to detect alterations or damage, if the equipment has been listed by a qualified electrical testing laboratory that is recognized as having the facilities described.... end quote Identical language appears in the 1978 NEC in 90.3.

You, of course, wouldn't have to mention the part about "listed". The standards for a UL508A manufactured control panel, in any case, can be very different from what is allowed by the NEC.

If the boards are not "listed" the inspector is guided by quote

110.3 Examination, Identification, Installation, and Use of Equipment (A) Examination In judging equipment, considerations such as the following shall be evaluated: end quote A list follows. The 1978 NEC is essentially identical

If the installation had a permit and was inspected when installed the inspector used his discretion under 110.3 to allow the equipment to be used. The OSHA inspector is now challenging the decision made by the electrical inspector. The OSHA inspector is not a specialist in the field and does not have the breadth of experience to evaluate what you have. The electrical inspector (presumably) did.

The OSHA inspector may be happy to find a reason to drop his objection. Would he take a statement from "one local inspector"? Statement from manufacturer? A letter from a professional EE should work, but may not be the cheapest.

Made by a major manufacturer? (Acme would certainly have made boards that conform to industry standards.)

What OSHA reg is the inspector citing? If the NEC, what OSHA reg allows that? Are there OSHA inspectors that specialize in electrical?

-- bud--

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random name

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