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Attached Garage #79759 01/19/02 11:01 AM
Joined: Jan 2002
Posts: 13
Ron Hoback Offline OP
A new home being built with an attached garage. The wall between the home and the garage is fire rated. Is it permissable to put outlets anr/or switches on either side of this wall? Is there a fire rating for metal switch boxes? How about a fire rating for plastic switch boxes?

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Re: Attached Garage #79760 01/19/02 11:05 AM
Joined: May 2001
Posts: 717
George Corron Offline
BOCA code 714.1.6.1 says you cannot have an outlet facing in opposite directions within 24" of each other in a fire wall. The purpose is to eliminate the possibility of a fire in one room traveling to the other side of the wall to the next room, which would defeat the purpose of the fire wall.
It your area adheres to the BOCA, it would be a violation.

Re: Attached Garage #79761 01/19/02 11:32 AM
Joined: Oct 2000
Posts: 2,749
Joe Tedesco Offline
2002 NEC:

300.21 Spread of Fire or Products of Combustion.

Electrical installations in hollow spaces, vertical shafts, and ventilation or air-handling ducts shall be made so that the possible spread of fire or products of combustion will not be substantially increased.

Openings around electrical penetrations through fire-resistant-rated walls, partitions, floors, or ceilings shall be firestopped using approved methods to maintain the fire resistance rating.

FPN: Directories of electrical construction materials published by qualified testing laboratories contain many listing installation restrictions necessary to maintain the fire-resistive rating of assemblies where penetrations or openings are made.

Building codes also contain restrictions on membrane penetrations on opposite sides of a fire-resistance–rated wall assembly.

An example is the 600-mm (24-in.) minimum horizontal separation that usually applies between boxes installed on opposite sides of the wall.

Assistance in complying with 300.21 can be found in building codes, fire resistance directories, and product listings.

Go to for more information.

Joe Tedesco, NEC Consultant
Re: Attached Garage #79762 01/19/02 12:37 PM
Joined: Jun 2001
Posts: 161
Mike Wescoatt Offline
Some palstic boxes are fire rated and they'll say right inside them how long they are rated for. You can use these as part of a properly constructed firewall system as described above. There are also intumescent putty pads that will attach to the rear of the box to keep the fire rating of a wall, but this requires access to the rear of the box to install properly.

Mike Wescoatt
Re: Attached Garage #79763 01/19/02 06:02 PM
Joined: Sep 2001
Posts: 26
johngeorge Offline
I have to type this all over again because the site is case sensitive so here it goes.
The wall that seperates the garage from living space is an area separation wall that can have a 3/4 or 1 hr rating. This means that this particular wall design has been tested by companies like U/L and they have determined the resistance to fire and heat is good for a certain time period. When the wall is tested certain allowances are made for outlets switches etc. and are tested accordingly. The plastic boxes with the 2hr rating embossed on the inside of the box, have also been tested in these walls, and the electrician can tell which box he can use and where they can be installed in relation to other outlets in the same wall. This information is all found in the listing and can be looked up in the white or green U/L directories. The metal boxes have been tested by category and not by manufacturer and all are restricted to 16 sq in in size. Some 3 gang plastic boxes have been listed for 2 hr walls and Allied has had a 3 gang box listed for a two hour wall with another 3 gang allied box back to back. So its all in the listing when it comes to plastic boxes. Caution should be taken when installing a flush panelboard in this fire rated wall - on either side - because there are no fire rated panelboards manufactured.
Your question is a good one and should be taken seriously by other electricians and other trades as well. This wall is not just "another" wall. You can check out the web sites of the Gypsum manufacturers - they contain a lot of information for the asking.

Re: Attached Garage #79764 01/20/02 02:09 PM
Joined: Sep 2001
Posts: 25
dlabrenz Offline
I guess I don't see this as that much of a problem.
The wall between the garage and the dwelling is not a true fire wall in the sense that it has no rating.

If my memory about BOCA is correct, all it requires is 5/8 dywall on the GARAGE side of the wall. All UBC and CABO requires is 1/2 in drywall on the GARAGE side of the wall.

The Interational code (that I assume we you all will be enforcing soon) reads as follows

R309.2 Separation required. The garage shall be separated from the residence and its attic area by not less than 1/2-inch(12.7 mm) gypsum board applied to the garage side.Where the separation is a floor-ceiling assembly, the structure supporting the separation shall also be protected by not less than 1/2-inch (12.7 mm) gypsum board or equivalent.

As you see even the Interational Residential Code doesn't call it a fire wall (it even seems to ignore whats on the side of the wall not facing the garage.


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