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#100764 - 01/02/07 07:34 PM Panels in basement  
FlatLine  Offline
Junior Member
Joined: Jan 2007
Posts: 7
Frankfort, Ky, USA
our inspector requires panels mounted in basements to be seperated from the concreate wall by plywood. Does anyone know in the code where it requires this? Also, If the wall is studed and the panels are mounted to the studs with the concrete behind them, would this still require the plywood?


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#100765 - 01/02/07 07:37 PM Re: Panels in basement  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
Not an NEC requirement.


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#100766 - 01/02/07 08:08 PM Re: Panels in basement  
ShockMe77  Offline
Member
Joined: Jun 2005
Posts: 821
Rahway, New Jersey
I would ask the AHJ wich article in the NEC he is referring to if he's requiring you to do this. I did some looking around at article 408, and from there one of the articles referred me to 312.2 (A). As long as the panel is elevated 1/4" off the concrete wall I don't believe there is a violation. However, unless a panel is mounted between two studs I ALWAYS use a sheet a plywood as a barrier from the concrete wall. Think corrosion.


#100767 - 01/02/07 08:45 PM Re: Panels in basement  
FlatLine  Offline
Junior Member
Joined: Jan 2007
Posts: 7
Frankfort, Ky, USA
thanks alot, It's probably just a local requirement due to the corrosion like you stated.

I have seen the 1/4" rule before, I guess with no studs the plywood gives the 1/4" and the corrosion.


#100768 - 01/02/07 09:11 PM Re: Panels in basement  
ShockMe77  Offline
Member
Joined: Jun 2005
Posts: 821
Rahway, New Jersey
I had an inspector once who wanted sheet metal placed behind the plywood!

Anyone have any idea why?


#100769 - 01/02/07 09:37 PM Re: Panels in basement  
HLCbuild  Offline
Member
Joined: Dec 2004
Posts: 209
Herndon,Va USA
Termite shield...you wouldn't want those termites to eat the plywood and get corrosion on their little bodies would you!


#100770 - 01/02/07 09:45 PM Re: Panels in basement  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,142
Estero,Fl,usa
The sheet metal protects the plywood (vapor barrier) and the plywood protects the panel?
I would think VisQueen would do the same thing. If the basement walls are damp you can make the 312.2 (1/4") rule work.


Greg Fretwell

#100771 - 01/02/07 09:54 PM Re: Panels in basement  
ShockMe77  Offline
Member
Joined: Jun 2005
Posts: 821
Rahway, New Jersey
I figured the sheetmetal was for some sort of protection for corrosion, but why isn't it in the code somewhere?

Or maybe the AHJ was using 300.6 as his justification.

Anyway, I only did it a few times and no one has enforced it since.

Gfretwell, you're an inspector, right? Do you enforce this?


#100772 - 01/02/07 09:59 PM Re: Panels in basement  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,142
Estero,Fl,usa
I didn't do that much residential. In commercial the enclosures were usually on strut. Also we don't have basements. [Linked Image]


Greg Fretwell

#100773 - 01/02/07 10:23 PM Re: Panels in basement  
ShockMe77  Offline
Member
Joined: Jun 2005
Posts: 821
Rahway, New Jersey
I forgot that basements are non-existant in some areas of the country. I just got back from the Carolina's and they didn't have any down there either. I've become so accustomed to them that I could not imagine not having one. Where would I store all my crap? LOL.

By the way, isn't all concrete considered to be a damp location? And why don't inspectors enforce 4x4 metal boxes on concrete walls be mounted on some sort of wood? If we do it for panels, we should also do it for any metal electrical box.


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