Fire Alarms Conduit size

Many electricians tell me that the minimum EMT conduit size for fire alarms is 3/4" I can't find any reference in any code book that supports this. Can someone point me to a reference or is the 3/4" not required by national codes?



Reply to
dave evans
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You can use 1/2 " conduit for fire as long as you do not exceed the amount of conductors allowed.

The codes and tables can be found in the NFPA-70- National Electrical Code. and on some internet sites. Theres also couple apps for sizing boxes and conduit available.

A code book can be purchased on line or at most electrical supply houses. You should not be installing or touching fire alarms with out a copy of it and NFPA 72 fire alarm signalling code . Or you will find your self in a big world of shit when things go very wrong.

Most electricians spec 3/4" because its standardizes the run and allows for expansion in future. But there is no such code which requires 3/4" unless it is a specific local code which I do not know of any.

Reply to
nick markowitz

I've heard that many times too, mostly from electricians that have lost the bid and complained when they see me running 1/2". I believe it falls into the same category as the "requirement" that all fire alarm conduit must be red in colour.

The practice of specifying a minimum 3/4" conduit size probably started before addressable SLC circuits drastically reduced the number of conductors in fire alarm raceways.

I have seen numerous job specs that call for a minimum of 3/4" conduit and a few that specify red conduit but I don't believe you will find either anywhere in the NEC.


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I think people get confused because many commercial jobs won't allow anything smaller than 3/4 conduit. Not a code, but it's often spec'd that way

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