(?) on 408.5

[augie47]

IN the '05 Code, 408.5 has been moved to Section I.

I have been asked an opinion on an installation where several panelboards are mounted in an UL bi-fold door enclosure (a factory assembled service distribution center)
The panelboards are high enough in the cabinet to provide proper bending radius on all conductors.
However, some of the conduits entering the open bottom enclosure require seal-offs. By the time a seal off and a nipple/bushing are installed, the conduits are more than 3" above the floor. The local AHJ has rejected this.
The only bussing in the cabinet is part of the individual panelboard bussing (pb's have nor enclosures, only dead-fronts)
(a) Do you guys agree this is a proper applicatuion of 408.5?
(b) Does anyone know the reasoning behind the 3" rule? I can understand the clearance from bussbar
requirement, but not the 3" requirement.

 

[websparky]

Re: (?) on 408.5

I would look at 300.4(F) and see if you can remove some of the fittings to lower the conduit.

 

[infinity]

Re: (?) on 408.5

So 408.5 is saying that if I enter an open bottomed switchboard I'm only allowed to have 3" of conduit penetrating above the floor within the switchboard?

How would it be possible to install a riser clamp and a EMT connector with bonding bushing on a large conduit, say 4" and only have it 3" high? Where did the 3" dimension come from?

 

[augie47]

Re: (?) on 408.5

my point exactly (and my question).....add a seal-off..definite problem.....anyone with a ROP?

 

[steve66]

Re: (?) on 408.5

I don't know if that was the intent, or this is a proper application article. But if your inspector sticks to his guns, I have a couple of possible solutions:

1. Can you raise the switchboard up? Maybe on a steel or concrete frame.

2. Can you cut out a recess in the concrete under the switchboard, so your seal-offs start below the finished floor level?

Steve

 

[necbuff]

Re: (?) on 408.5

I am taking a stab here, but I am probably the AJH in question who will not accept this. Here goes... 408.5 states conduits or raceways including their fittings may only extend up to 3" into the enclosure. There must also be not less than an 8" clearance between the end of the fitting and any insulated busbars, or 10" between any uninsulated busbar. The seal-offs should not be in the panel. In cases such as above, a curb or "well" would need to be in place to rise the gear above the spill pad. The picture may be seen on my website in the code blunders section, at www.electricaled.com.

note: No photo on my site is meant degrade any installer. Pictures are educational and the installer will not be revealed.

[ September 28, 2005, 06:10 PM: Message edited by: necbuff ]