fire walls and plastic boxes

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Joseph Alexander

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METAL BOXES IN A FIRE RATE ASSEMBLY ARE LIMITED TO A MXIMUM OF 16 SQUARE INCHES (PER IBC 714.4.2) WHAT ABOUT PLASTIC BOXES ARE THEY LIMITED ALSO?
 
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Strathead

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Ocala, Florida, USA
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Electrician/Estimator/Project Manager/Superintendent
It isn't the box that is limited to 16 square inches, it is the opening. So a 4S box with a single gang mudring has an opening of 3x2 or less. 714.4.2 exception 2 answers your question regarding plastic boxes.
 
augie47

augie47

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Plastic boxes of ANY size in a fire rated assembly can pose firestop problems.
 
augie47

augie47

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State Electrical Inspector (Retired)
NTesla76 said:
There are nail on boxes with UL fire ratings stamped inside the box.
Click to expand...
Understand but, depending on the install, sometiimes that "rating" requires additional steps.
There are folks here than can elaborate but the rating marked in the box can have "stipulations"
i know building inspectors have required "more" than just a box with a 2 hr stamp
 
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