BRK Smoke Alarms

[goldstar]

I think I was just PO’d that I didn’t find the Firex relay at the outset :happyyes:

 

[gadfly56]

I think I was just PO’d that I didn’t find the Firex relay at the outset :happyyes:

Just so you know, that sort of lash-up isn't code compliant. The wiring to that relay is unsupervised so if it came loose, you'd never get a signal to the fire alarm control unit and you wouldn't even know something is wrong. Actually, none of the smoke alarms are either, so double-plus ungood.

 

[LarryFine]

Does anyone know the voltage on the interconnect conductor, and whether they're all the same?

 

[GoldDigger]

Is there a limit to the number of interconnected units without using multiple zones and relay(s) to join them?
With some circuit designs unalarmed units might be leaking enough signal onto the interconnecting wire to cause a false trip when all are added together.

 

[gadfly56]

Is there a limit to the number of interconnected units without using multiple zones and relay(s) to join them?
With some circuit designs unalarmed units might be leaking enough signal onto the interconnecting wire to cause a false trip when all are added together.

For your usual 120VAC interconnected devices with battery backup, a maximum of 18 alarm devices, 12 of which may be smokes, is allowed, unless they are supervised then it's 64 and 42. No multiple zones with relay interconnects; they are all one big happy family. If you have a panel with connected low voltage smoke detectors, that's a whole different ball game.

 

[JFletcher]

Does anyone know the voltage on the interconnect conductor, and whether they're all the same?

Wag, I would think 9 volts or less since the interconnect will operate on battery power.

Schneider Electric list the voltage of their interconnect at 5 volts with a maximum of 9 volts with the
755PSMA2 model.

I would think that all battery backup smoke alarms would have the same or similar enough voltages on the interconnect wire to allow mixing and matching, though the instructions probably disallow that installation.

 

[GoldDigger]

For your usual 120VAC interconnected devices with battery backup, a maximum of 18 alarm devices, 12 of which may be smokes, is allowed, unless they are supervised then it's 64 and 42. No multiple zones with relay interconnects; they are all one big happy family. If you have a panel with connected low voltage smoke detectors, that's a whole different ball game.

I was thinking more about the practical limitations of particular designs rather than code requirements or generic behavior. The smoke alarms we are looking at here do not AFAIK have any provision for supervision.

 

[goldstar]

Just so you know, that sort of lash-up isn't code compliant. The wiring to that relay is unsupervised so if it came loose, you'd never get a signal to the fire alarm control unit and you wouldn't even know something is wrong. Actually, none of the smoke alarms are either, so double-plus ungood.

I know that to be true by today’s codes and standards but this installaion was done a long time ago. I’m not sure if it was ever acceptable to interface them with an alarm system. The woman’s husand obviously knew what he was doing at the time.

 

[gadfly56]

I know that to be true by today’s codes and standards but this installaion was done a long time ago. I’m not sure if it was ever acceptable to interface them with an alarm system. The woman’s husand obviously knew what he was doing at the time.

What would have been compliant is if the interconnected smoke alarms met all the placement and coverage requirements and the panel was really acting as auxiliary equipment, or if each smoke alarm had a smoke detector twin.