How do I fire block outlet boxes in my garage ceiling?

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  #1  
Old 01-19-13, 11:40 AM
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How do I fire block outlet boxes in my garage ceiling?

I have a garage addition with a living space and bedroom above it. I plan on using 5/8" sheetrock on the ceilling but also need electrical boxes for lights and the garage door opener. How do fireblock them. Are there special boxes I should use or a product that will do the job?
 
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Old 01-19-13, 11:49 AM
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Just use regular boxes, properly supported with your mud on the sheetrock within 1/8 of the ring. In addition you can buy Fire Stop caulking (red) at the box stores to finish the seal around the boxes. What type lighting are you proposing?
 
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Old 01-19-13, 11:57 AM
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Some of the information here may be helpful.

http://www.sjgov.org/commdev/cgi-bin...E_LID_WALL_REQ

http://www.gaylor.com/what_we_do/kno...ated_walls.pdf

I believe you will need to use 1 hour rated metal boxes with mud rings. You won't have to worry about a 2nd penetration since you probably won't have floor outlets in the room above. You may want to install fire blocking on either side of the metal box within the floor joist, and insulate the space above the box with a fire rated mineral fiber insulation, assuming you are using standard fiberglass everywhere else.

You could also surface mount all of your electrical boxes and conduit so that there are no penetrations.
 
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Old 01-19-13, 11:58 AM
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I plan on using 4' floresents with a cord and plug. My concern is that altough I can seal the gap between the box and the sheetrock, the box itself has holes and I don't know if they provide enough of a fire block.
 
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Old 01-19-13, 12:01 PM
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Are the materials you suggest available at Home Depot or do I need to find an electrical supplier.
 
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Old 01-19-13, 12:18 PM
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This is an example of the style you would probably want to use. Notice it specifically states it's fire rating.

http://www.homedepot.com/Electrical/...1#.UPryRB3LRmA

mud ring:

http://www.homedepot.com/Electrical/...1#.UPryyh3LRmA
 
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Old 01-19-13, 12:20 PM
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Many of the plastic boxes are two hour rated. This is higher than the 5/8" drywall.
 
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Old 01-19-13, 01:27 PM
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Yeah, don't overthink this, as the materials you are using have a higher rating than the sheetrock itself. Do a diligent mud job around the mud rings and seal gaps as you see fit, and it will work. If you still feel it is inadequate, use wire mold or conduit and surface mounted boxes.
 
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Old 01-19-13, 06:33 PM
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14 or 15 years ago there was only one manufacturer who made a fire rated plastic box. Today, most plastic boxes are fire rated. Most likely, way back then there was only one manufacturer who had gone to the expense to have it's box tested by U.L. to meet fire rating requirements.

My concern is that altough I can seal the gap between the box and the sheetrock, the box itself has holes and I don't know if they provide enough of a fire block.
If you still have concerns, treat your boxes like a commercial job and use 3M putty pads on the boxes.

3M US: BCSD - Product Catalog: 3M
 
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