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wiring smoke detectors - parallel/series

C1802362's picture

I'm in the attic re-insulating and my wife wants to add smoke detectors to each bedroom - do I run the 3-way wiring between all the detectors in series or in parallel?


(post #107485, reply #1 of 9)

Good move putting in connected smoke detectors.

Each one needs a hot, a neutral, and 1 wire conecting them all, normally the red one.

Series and parallel are terms that easily get mis interpeted.

(post #107485, reply #2 of 9)

understand the connection - what I'm wondering is can I run the detectors from each room to a junction box with the line back to the main panel, or do I have to connect one detector to the next to the third and so on (in other words a continuous circuit that goes from room to room) before I hook the last one up to the home run?

Sorry about the parallel and series terms - I'm using it from my basic electricity classes.


(post #107485, reply #3 of 9)

Having the red black and white wires run from each SD back to a j box with power feeding the white and black should work just fine.

(post #107485, reply #4 of 9)

The electrical circuit has to be parallel, but the phisical wiring can be run either way theoretically. I suppose it depends on how many wires will end up in one junction box and what the box fill limit is. Virtually all home elctrical loads are wired in parallel, if not you would not have 110 at each fixture.

Edited 11/29/2008 3:17 pm ET by TomW

(post #107485, reply #5 of 9)

great - thanks

(post #107485, reply #6 of 9)

First let me say that I'm NOT an electrician.

I don't know of any situation in the normal wiring of a single family house where anything is wired in series. As a previous post said "the terms series and parallel or often confused and misunderstood".

I my neck of the woods, line voltage smoke/fire detectors are connected to an adjacent/near-by lighting circuit and on various circuits. I am told that this is because if that circuit trips or whatever, you are more likely to discover it more quickly. If all of the detectors are on one dedicated circuit and the circuit breaker trips, all of them will be disabled and you would not know it until it was to late. I suppose that if the power had not been off to long and the back-up batteries still were charged, you would be covered.

I repeat, I am NOT an electrician. I am just parroting what I have been told. From the for what it's worth department.

(post #107485, reply #8 of 9)

that code around here, must be hook to a circuit that you cant live with it bein=g turned off.

(post #107485, reply #9 of 9)

 That is what I was trying to say or at least to imply. What you said is better.




(post #107485, reply #7 of 9)

As someone else said, the white and black you run like any other appliance - the red is the signal wire. 

One thought:

I wish now I had a way to break the signal connection to all the detectors at once.  Every once in awhile, I have a detector go bad, get dirty, or just get a smoky kitchen scent and the whole house goes nuts... sometimes after the kids have gone to bed.

I wish I had a way NOW to isolate the one ringing detector!

Rebuilding my home in Cypress, CA
Also a CRX fanatic!

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