Smoke detctor in an 1943 duplex

[powerplay]

In an old duplex with a smoke detector on different panels on either side of the common wall, would it be practical to run an 3 wire cable with the black and white capped together and taped "do not use" and the red wire labeled "from the other suite" of common wall, and connecting red wires of all smoke detectors together with the same model of smoke alarm to signal with the low voltage signal circuit safely? If the extra wire is marked low voltage, there should be no shock hazard from the other wires, or perhaps I should just cut the black and white wires off the common cable? It is an 1943 duplex with only one story, and only 600sq feet a side with a crawl space, so no fire sprinklers or exterior bell are required that I know of.

 

[kwired]

Why do you want to tie them together if they are in separate dwelling units?

 

[powerplay]

To alert the adjacent tenant if there's a fire hazard? can be a nuisance, but in case the place requires interconnection?

 

[John120/240]

He just wants to notify the other tennants of the fire. Probably no fire wall

seperation. Maybe you could run a test & see if you can hear one in alarm

from the other unit. Then there is nusiance alarm from burnt popcorn or

bacon.

 

[kwired]

...Then there is nusiance alarm from burnt popcorn or bacon.

Exactly, this often leads to someone disconnecting the thing so they don't have to hear the false alarms rendering it useless to a fire in their own unit. The only right solution is the proper fire barrier between the units. It will give the occupants of one unit time that having no fire barrier may not.

 

[hurk27]

In an old duplex with a smoke detector on different panels on either side of the common wall, would it be practical to run an 3 wire cable with the black and white capped together and taped "do not use" and the red wire labeled "from the other suite" of common wall, and connecting red wires of all smoke detectors together with the same model of smoke alarm to signal with the low voltage signal circuit safely? If the extra wire is marked low voltage, there should be no shock hazard from the other wires, or perhaps I should just cut the black and white wires off the common cable? It is an 1943 duplex with only one story, and only 600sq feet a side with a crawl space, so no fire sprinklers or exterior bell are required that I know of.

I would say no as to the way your wanting to do this, most smoke detectors today use a 9 volt DC as a signal to trip the other alarms, this 9 volts is between the neutral and red wire, negative on the neutral and positive on the red, also this signal circuit is very current limited meaning only so many can be put on the circuit before it causes problems, this is also why each interconnected set of smoke detectors needs to be served by the same circuit, almost all manufactures do have two methods to over come this, one is a interface unit to go between the two sets of smokes, the other is a wireless unit placed in each system to interconnect the two, but the wireless might not be allowed by all AHJ's.

Go to the web site of the brand you have installed and see the options they have to interconnect two separated interconnected systems.

 

[gndrod]

1 hr. barrier

1 hr. barrier

A single 5/8 sheetrock cover on one wall side will be a one hour fire blockage.

 

[kwired]

A single 5/8 sheetrock cover on one wall side will be a one hour fire blockage.

You sure it doesn't have to be both sides, or 2 layers on one side?

 

[John120/240]

That will be a real PIA to install sheetrock in the attic to acheive your fire

rating. What is the cost-benifit ratio ? Yes a life is priceless, but tell that to

the landlord. As for the common wall in the living area use box extenders &

long screws.

 

[gadfly56]

Why do you want to tie them together if they are in separate dwelling units?

Unless specifically allowed by the AHJ, the IBC (if your jurisdiction uses it) forbids this.

 

[kwired]

Why do you want to tie them together if they are in separate dwelling units?

Unless specifically allowed by the AHJ, the IBC (if your jurisdiction uses it) forbids this.

I thought it may not be allowed but also wondered why you would want to do that anyway. Think about all the trouble that would be caused in say a 30 apartment complex if all 30 of them sounded alarm everytime someone burned something on the stove.