Is this kosher?

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dancase

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I've got a situation where there are two 2 1/2" rigid nipples sticking out of a concrete floor in the corner of a room. The nipples extend about 2" above the floor and are a pretty cockeyed. There used to be a 12 x 12 junction box that was loosely attached to these two conduits and sat about an inch off the floor. I'm replacing that box with an 18 x 18, and I'd like that box to sit on the floor rather than 1" above.

Looking at this, it would be pretty easy to cut the holes a little oversize and set the box down over the two pipes and get the results I want. I'd then use grounding bushings on the two pipes to bond them to the steel box. The oversized opening is closed (against the floor), fulfilling that requirment, and the conduits are bonded to the box. I've looked through the code and haven't found anything yet that would prohibit this -- am I missing anything here? Any violations I haven't thought of?

This isn't the kind of thing I like to do normally -- but I'm cleaning up someone else's mess and trying to do the best I can with what I've been given.

So, does this pass?

D.
 
Re: Is this kosher?

The first thing that comes to mind for me is that this is the same method used to stub up into service and other equipment cabinets. Sounds okay to me. :D
 
Re: Is this kosher?

If the conduits are solid, the box is secure, and the box is bonded to the conduits, I don't see a problem. I am also assuming you don't have a two ft hole for a one in. conduit either. :D
 
Re: Is this kosher?

300.10 Electrical Continuity of Metal Raceways and Enclosures.

Unless specifically permitted elsewhere in this Code, raceways and cable assemblies shall be mechanically secured to boxes, fittings, cabinets, and other enclosures.
 
Re: Is this kosher?

Originally posted by pierre:
300.10 Electrical Continuity of Metal Raceways and Enclosures.

Unless specifically permitted elsewhere in this Code, raceways and cable assemblies shall be mechanically secured to boxes, fittings, cabinets, and other enclosures.
Click to expand...
True. Now the philosophical question arises... what constitutes "mechanically secured"? The stub-ups are quite thoroughly secured in the concrete floor. If the box is also secured to the same floor, does that cover the "mechanically secured" requirement? To my mind, the intent of this requirement is to prevent things like nipples flopping around outside of boxes, and potentially causing conductor damage.

The primary point of 300-10 is met by securely bonding the two conduits to the box.

D.
 
Re: Is this kosher?

As mentioned by Kentirwin, this is almost exactly the same thing you do when setting large switchgear. Those don't have anything covering the bottom.

This is done every day accross the country, so I think you are alright as long as you use grounding bushings and bond the box.
 
Re: Is this kosher?

Every traffic signal cabinet you see that is pad mounted has an open bottom.
I agree with Pierres comment, but this type of installation is done commonly. Of course all the open bottom handhole enclosures were not legal until the 2005 NEC
 
Re: Is this kosher?

Originally posted by dancase:
Now the philosophical question arises... what constitutes "mechanically secured"? The stub-ups are quite thoroughly secured in the concrete floor. If the box is also secured to the same floor, does that cover the "mechanically secured" requirement? To my mind, the intent of this requirement is to prevent things like nipples flopping around outside of boxes, and potentially causing conductor damage.

The primary point of 300-10 is met by securely bonding the two conduits to the box.

D.
Click to expand...
Reminds me, the other day in our shop, another student, tripped, fell, and grabbed onto a peice of 1/2" GRC connecting recepticles on the side of a bench table. He literally snapped the pipe where it had been threaded, cutting the conductors, and shorting them to the grounded box. Made some pretty impressive sparks. :D My only concern is that if a box supported only by the GRC (assuming that the box is connectind to the pipe with locknuts) if it were to be whacked, would it come loose, or even snap the threads off the GRC?
 
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