Linking smoke detectors

[augie47]

One of the areas I work has just recently adopted the regulation requiring smoke detectors both inside the bedrooms and in common areas and all levels, with all detectors "linked" (IRC). Most contractors are either wiring the detectors to a bed-room arc fault circuit, or putting in a seperate smoke detector arc-fault circuit.
Not wanting to "rehash" the wisdom of the detector being on an arc-fault, I have a question. If the bedroom smoke detectors are on the bedroom circuit (AF) and detectors in other areas are on a different circuit, can these detectors be linked simply by inner-connecting them from linking terminal to linking terminal ?
In othe words can detectors on seperate circuits be linked? If so, is it permissible to link them with a single conductor, such as a 14THHN (I know the link circuit does not have line power)?
If one does this is it a violation of 300.3(B) ?

 

[iwire]

Re: Linking smoke detectors

Originally posted by augie47:
In othe words can detectors on seperate circuits be linked? If so, is it permissible to link them with a single conductor, such as a 14THHN (I know the link circuit does not have line power)?

Hey Augie, I have some smokes here at home that the instructions say you can have them on separate circuits but must be on the same leg of the panel. They also recommend one circuit.

So I think the answer to your question is it depends on the manufactures instructions.

The interconnect on these ones is 9 VDC so any size wire would work.

 

[allenwayne]

Re: Linking smoke detectors

IRC that really s_ _ _ s,they still have to be interconnected....... inside a bed room outside each bed room as far as I know within 10 ft of the door and top and bottom of the landings.Also stay trimmed out 36 in. from any FORCED air vent and also bathroom doors when there is a vent fan in them also count

 

[allenwayne]

Re: Linking smoke detectors

Also the highest point in a home within 1 ft down and 3 ft from ceiling peak (forgot that one)

 

[benaround]

Re: Linking smoke detectors

Augie,

If you are refering to the common 3 wire 120vac interconnecting smokes,that (orange) link is an open grounded conductor until there is an alarm then it closes and sends out to the others.

 

[iwire]

Re: Linking smoke detectors

Here is some info from Firex.

Use #18 AWG minimum solid or stranded wire. When interconnecting, maximum wire length between any two is 1,500 feet for #18 AWG or 4,000 feet for #14 AWG (20 OHMS loop resistance).

DO NOT connect to any other type or model of heat or smoke alarm. Connect smoke or heat alarms to a single AC branch circuit. If local codes do not permit, be sure the neutral wire is common to both phases

Firex