[rjniles]

I want to replace my existing 15 year old smoke detectors. I have 4 detector that are 120 volt with 9V battery backup; they are not interconnected. The existing smokes are wired to 3 different circuits: 2 on a 20 amp circuit that feeds lights & receptacles in the dining room, one each on 15 amp bedroom lighting circuits.

I want to interconnect the new smokes. Here is a reference to the FireX smokes I want to use.
http://www.sentrydetectors.com/firex/manual/4618.pdf

I am aware that usually interconnected smokes use 3 wire cable and use the red wire to make the interconnection. I would prefer not to have to rewire the four locations.

The manual listed above indicates the interconnection can be made using 18 gauge wiring so I think the interconnection signalling is low voltage. I would like to run a single strand of #14 THWN between the existing boxes to make the interconnection. The FireX manual cautions that if different circuits are used to power the smokes, the neutrals originate from the same phase. This will require I rearrange one of the circuits at the breaker panel but is a minor issue.

My question is: Is my plan to run a single THWN wire (no conduit) between the smokes a code compliant method?

 

[oleguy74]

has to be in conduit or cable.single wires can't be run like that.

 

[SD515]

I don’t think so. Fire alarm systems can have some different rules than the norm, but the typical household smoke alarm is not considered to be fire alarm equipment, therefore the special rules of fire alarms don’t apply. Which means the general rules of branch circuits would apply, and those rules wouldn’t allow it.

Also, this is the wording from the firex link you posted….
Connect smoke alarms to a single AC branch circuit. If local codes do not permit, be sure the neutral wire is common to both phases.
I read that to say that the phases share the neutral….an MWBC.

 

[rjniles]

OP here rehashing an old question.

I hooked up one of the detectors I am planning on using (see original post) with a cord and plug for testing. I used the test button to set off the alarm and used a meter to test the signal on the red wire from the detector. I get 9 VDC.

Does this make any difference to my original thought to use a single #14 THWN wire to interconnect the smokes (without cable or conduit)?

 

[electures]

OP here rehashing an old question.

I hooked up one of the detectors I am planning on using (see original post) with a cord and plug for testing. I used the test button to set off the alarm and used a meter to test the signal on the red wire from the detector. I get 9 VDC.

Does this make any difference to my original thought to use a single #14 THWN wire to interconnect the smokes (without cable or conduit)?

All conductors of a circuit shall be contained in the same cable or conduit. You have to run 14/3.

300.3 Conductors.
(A) Single Conductors.​

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Single conductors specified in Table 310.13(A) shall only be installed where part of a recognized wiring method of Chapter 3. Exception: Individual conductors shall be permitted where installed as separate overhead conductors in accordance with 225.6.​

(B) Conductors of the Same Circuit.​

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All conductors of the same circuit and, where used, the grounded conductor and all equipment grounding conductors and bonding conductors shall be contained within the same raceway, auxiliary gutter, cable tray, cablebus assembly, trench, cable, or cord, unless otherwise permitted in accordance with 300.3(B)(1) through (B)(4).​

 

[vsheetz]

When I did my whole house remodel a couple years ago, I installed battery powered wirelessly communicated smoke alarms. Works well, easy install. Might be an option to consider if allowed in your locale.

 

[rjniles]

When I did my whole house remodel a couple years ago, I installed battery powered wirelessly communicated smoke alarms. Works well, easy install. Might be an option to consider if allowed in your locale.

I looked at those but they were a little to rich for my blood $$$)

 

[vsheetz]

I looked at those but they were a little to rich for my blood $$$)

Depending on the situation by the time you subtract out wiring costs, the delta is not that much.