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Fire blocking and the building code. #95442
09/13/05 07:15 PM
09/13/05 07:15 PM
Joey D  Offline OP
Joined: Oct 2003
Posts: 259
Arlington MA U.S.
I got called on an inspection today for my boxes in a fire wall between two condo's. The inspector and myself didn't see the hr rating on the box. It was there I just missed it. He told me about these puddy pads that go over the box to make it comply.
I solved that issue but now there is an issue about boxes in the same bay. They need the pad and fire block insulation around them.
My point is should I be doing all this or should I just tell the contractor to do it as it's a building code?
Any projects from here on in will have a note about this though to cover myself.

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Re: Fire blocking and the building code. #95443
09/13/05 07:57 PM
09/13/05 07:57 PM
HotLine1  Online Content

Joined: Apr 2002
Posts: 7,081
Brick, NJ USA
As far as I know, the EC's around here do the putty pads/fire blanket thing. There's a 19 bldg apt complex going up, and the EC is doing the putty pad thing. There is supposed to be a 'rated box', but I have not seen it yet.

Careful layout avoids the multiple boxes in the same bay.....they need a minimum 24" spacing to the best of my knowledge.


Re: Fire blocking and the building code. #95444
09/13/05 10:18 PM
09/13/05 10:18 PM
e57  Offline
Joined: May 2003
Posts: 2,876
We have to do it all the time. Putty pads, chalking. Recently found a good, (Darn pricey) foam that works well for multiple penetrations with conduit, made by Hilti.

Mark Heller
"Well - I oughta....." -Jackie Gleason
Re: Fire blocking and the building code. #95445
09/14/05 06:17 PM
09/14/05 06:17 PM
Redsy  Offline
Joined: Mar 2001
Posts: 2,056
Bucks County PA
Allied Moulded Products Inc. makes a fiberglass box that, according to the literature reduces separation requirements from 24" to 3" without the use of putty pads.

[This message has been edited by Redsy (edited 09-14-2005).]

Re: Fire blocking and the building code. #95446
09/14/05 06:51 PM
09/14/05 06:51 PM
eprice  Offline
Joined: Aug 2003
Posts: 64
North Logan, Utah, USA
With any non-metalic box, it's use in a fire rated wall depends on it's UL listing. When it comes to installing boxes in oposite sides of the same rated wall, the separation required varies greatly not only between manufacturers, but between different boxes by the same manufacturer. This information can be found by going to The UL web site and searching for UL categories QBWY and CEYY. I was able to find information for Allied boxes which can be spaced 3" apart as Redsy stated, but the wall must contain bat insulation.

I remember inspecting a motel where the electricain had used a variety of boxes by different manufactures. There were 6 or more different standards that needed to be applied throughout the building on a case by case basis depending on which box was used at a particular location. What a nightmare. My advise is, settle on a particular type of box that you will use throughout a project and stick with it. Find the UL information on the installation requirements for that box and use that information. Have it available for the inspector when he come.


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