We have 4 heaters in a commercial building. These heaters draw about 4 amps and have 3' cord and plug, there is no provisions for it to be hard wired.

I would like to run emt above the heater to 4 square box. From out of that box I would like to drop SO cord, 3'-6' in lenght, with a strain relief connector (kellum style) at the 4 square and a SO cord receptacle at the other end to plug the heater in. Is this legal?

To determine if it is compliant will rest in the hands of your local AHJ.

IMHO, based on what you stated, I would be OK.

A 'way around' the objections of some AHJs may be to install a single receptacle in the 4 Sq, and put a male cap on your cord w/strain relief.

If you think about what you describe...your 'scope' could only be the receptacles above the heater locations, with the client providing a 'short' extension cord to plug in the heaters.

Hrm, I would of never guessed an extension cord. I get a bunch of residential rental home repair work that calls for removing of extension cord. This is typically a fridge or TV in the basement a tenant has ran an extension cord to and I need to add a receptacle for it.

This could be just because its a rental property.

Cord for connections to equipment has been an unending debate.

The usual solution for 'cord drops' is a twistlock receptacle within a 4x4 box at the bar joists; a strain relief on the cord, and a suitable cord cap on the end of the cord. The equipment supply cord plugs in.

IMHO, the above is compliant.

I have no issue with your plan, indeed, it's something I like, and have done several times. I have seen it work out very well in the most demanding environments.

Too bad it's against code.

The NEC requires pendant receptacles to be in a box with a threaded hub.

Idiocy, IMO. I think they MEANT to preclude the use of simple 4-square boxes, or it was an 'end run' to try to ban DIY extension cords. Yet, in the process, they banned the common cord cap.

I can't find the pic, but...
One guy tack welded a 1/2" pipe coupling to a 4-sq, used a strain relief cord connector and insisted it met the intent of the NEC.

I believe he originally had a 1/2" chase nipple thru the KO into the coupling, but had issues with the tightening.

Interesting question. What about a bell box with threaded entries? Those pendant cords, with twist lock plugs were pretty popular in fast food joints to serve equipment that they rolled around to clean under. I just never had a reason to see what was above the ceiling. (I was "data" in those days)

Greg:
Equipment that requires 'moving' for sanitation like fast food locations has been using:
Suitable box mounted face down in ceiling with a receptacle in the box, a cord cap w/strain relief with a female cap. The equipment is connected to the 'hanging' female cap.

There is the same setup in the pharma/HABA facilities here for sanitation and 'line swap' reasons.

I got the impression that our fire marshal was not allowing any "extension cords" when we were working in computer rooms. I know I had a customer with some cords made up with SO and Russell Stoll connectors on each end. They got tagged.
The customer ended up having to move the fixed in place receptacles whenever they moved the equipment.

That sounds like a FM with either an issue, or not understanding.

He cited 400.8(1)<cords not permitted> As a substitute for the fixed wiring of a structure.

If the pendant or the pigtail under the floor was started in a box, he was OK with it. You just could not have an extension cord for a load that was in regular use.
Needless to say power strips and orange cords suddenly disappeared.
Nobody ever argued with him. I am nowhere near that these days so I am not sure what the current thinking is in Ft Myers.

I just asked my wife and she says the "city of Bonita" will let you get away with an extension cord if it is strapped to the wall. That is as confusing to me.

Getting back to the original question, I don't think a cord connector in a 1900 box meets 210.23(H)(1) (pendant boxes)



That was why I asked if a Bell box with threaded entries and the appropriate strain relieving connector, would fill the bill.

Greg:

"That was why I asked if a Bell box with threaded entries and the appropriate strain relieving connector, would fill the bill"

Yes, by definition...that would be compliant.

The debate revolves around using 'cord' where a Chapter 3 wiring method could/should be installed.

A good example is the power for the 'spot' refrig/freezers in the 'club' stores that are rolled out for "specials".

I think we are getting back to your first answer. What does the AHJ say.
We always had that issue under a raised floor.
The most practical answer was a whip with SO cord and the appropriate Russell Stoll connector but it is hard to find a code compliant way to do it and the things they would agree to were far worse. The typical answer was FMC and a box but that is not legal either because there are no FMC connectors that are legal on a whip. Without the FMC being strapped to the surface within a foot of the box, the thing pulls apart. Same with a cord connect style R/S on FMC. It will not hold.

I think Joe T has some pictures I took showing the scary stuff that happens.

The best suggestion is to talk to the local AHJ.

I have seen a lot of scary things over the years, with SO/SOW/SJ, and yes even good old 'zip cord'.

I see a few 'cord drops' attempts in warehouses still by guys who slip in under darkness. The ECs that are the 'regulars' know the drill.

This gets back to 'you reap what you have sown.'

Prior to the '99 code, there was no problem with making your own equipment using ordinary boxes or cord caps. Then, along came an activist (no point naming him at this point).

That fine gent flooded electrical forums with pictures of damaged home-made 'power strips.' The usual culprit was simply missing screws, with physical damage coming in second. Next thing you knew, the code had that 'pendant' provision in it, and everyone was applying 'pendant' requirements to cords that lay on the floor.

Since then, there have also been two new code requirements adopted regarding 'industrial' covers.

I believe the code panel worded the 'pendant' requirement with the cast-iron "FS" box and Kellums grip in mind. Alas, the wording also allows for the use of a "Bell" box - and a simple field-added cord connector was banned. They also inadvertently banned the very nice Daniel Woodhead, UL-listed product (it has an integral clamp and no hub). Unintended consequences.

On another front, OSHA piled on, trying to incorporate unique GFCI requirements.

The biggest irony is that all this hoopla can be traced directly to UL's refusal to list 'power strips' for years on end, citing an expansive application to the 90-watt load calculation in commercial settings.

Let me give you one of the laws of life: where there is a need, it will be met. If you prevent folks from buying a solution, they will make one.

I'll give you another: It's simply impossible for any code panel to write a rule that can foresee every possible circumstance, now and forever.

Taking pictures of damaged equipment and using them to write a rule that you then apply to entirely different situations is nothing more than fraud put forth by a tyrant. The 'reformer,' in this case, has done this several times. I call it 'bait and switch.' Alas, it seems to be a common tactic these days.

There's also the arrogance of someone assuming that they possess the wisdom to second-guess decades of success by experienced professionals.