Disconnects

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chuck417

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Can the disconnecting means for fixed electrical space heating equipment be mounted to the ductwork? If not, what section of the 2005 NEC prohibits that?
 
There is no NEC section that prohibits mounting the disconnecting means for fixed electric space heating equipment on a section of ductwork.

Chris
 
How are you going to seal the mounting holes that you punched in the duct work? In CA they require duct testing so this could cause a problem.
 
chuck417 said:
Can the disconnecting means for fixed electrical space heating equipment be mounted to the ductwork? If not, what section of the 2005 NEC prohibits that?
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If not the word, the spirit of the NEC would be in disagreement.

The general concept being that electrical equipment is installed in and on places, surfaces and supports that are DEDICATED and DESIGNED for that purpose.

An air-conditioning duct is hardly something that is designed, sized and installed to provide structural support for anything. If the duct-work is modified, they need to call an electrician? If the NEC does not specifically prohibits this the HVAC codes may, so check that if you want to pursue this method of installation.
 
weressl said:
If not the word, the spirit of the NEC would be in disagreement.

The general concept being that electrical equipment is installed in and on places, surfaces and supports that are DEDICATED and DESIGNED for that purpose.

An air-conditioning duct is hardly something that is designed, sized and installed to provide structural support for anything. If the duct-work is modified, they need to call an electrician? If the NEC does not specifically prohibits this the HVAC codes may, so check that if you want to pursue this method of installation.
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I agree with weressl. To add, I'm sure the manufacture instructions don't recommend this sort of an install.
 
weressl said:
OK? Your point?

Do you claim anything to be there that is different from what I wrote?
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It appeared to me you where indicating that mounting a disconnect in any space not dedicated and designed for that purpose would be against 'the spirit of the NEC'.

weressl said:
If not the word, the spirit of the NEC would be in disagreement.

The general concept being that electrical equipment is installed in and on places, surfaces and supports that are DEDICATED and DESIGNED for that purpose.
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IMO 440.14 shows that there is no actual or 'spiritual' ;) violation of the NEC.

I will also add that above ceilings it is very common practice to mount the disconnecting means for the various HVAC units right on the unit itself.
 
iwire said:
It appeared to me you where indicating that mounting a disconnect in any space not dedicated and designed for that purpose would be against 'the spirit of the NEC'.



IMO 440.14 shows that there is no actual or 'spiritual' ;) violation of the NEC.

I will also add that above ceilings it is very common practice to mount the disconnecting means for the various HVAC units right on the unit itself.
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No disagreement.

I said 'in general' that would not exclude specific exceptions.

HVAC unit in some cases provides structural provisions to mount equipment that services it. It is especially true for large rooftop units.

The question was about ductwork. While the NEC is silent about the issue I pointed out that reading the general trend an tone of the NEC one may surmise that electrical equipment should be installed in a certain way. We, in industry, DO spell this out more specifically. That's why commecrial and institutional installations can look like natural fertilizers while inductrial construction is more orderly.;)
 
weressl said:
IMO that would not be good workmanship.

I am surprised that we're even having this discussion.:roll:
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While I don't disagree with you, as an inspector I do not have the luxury of saying, "because I don't like it", I have to be able to reference the code. As an intaller you can put it in or take it out as many times as you want or install it to what ever level of perfection is acceptable to you.
 
Personally I like to stay away from mounting anything to ducts, they are generally flimsy and vibrate in operation. That said, everything is relative, a 200 amp 600 volt disconnect mounted on a 18" x 12" duct would likely be a problem, a 4" square box with a 20 amp switch in a raised cover mounted to the same duct would likely be fine.
 
I agree with Iwire's last reply. I'd have to be pretty desperate to mount anything to duct, it's usually just way to flimsy. Although some ductwork in plants is pretty thick...:cool:
 
iwire said:
It appeared to me you where indicating that mounting a disconnect in any space not dedicated and designed for that purpose would be against 'the spirit of the NEC'.



IMO 440.14 shows that there is no actual or 'spiritual' ;) violation of the NEC.

I will also add that above ceilings it is very common practice to mount the disconnecting means for the various HVAC units right on the unit itself.
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The OP was asking could it be mounted on the duct work
 
In this situation the HVAC unit is setting on the duct as part of the return system. I am more than certain that the duct will carry the weight of a 60 amp disconnect. Agree?
 
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