I am required to turn off a fan that feeds fresh air to acouple of rooms. The rooms are finished and surface wiring isn't an option. If I could use the interlok wire that interloks a regular smoke detector together that would be the simplest but was unable to find what signal they us to turn each other on??? I get about 10VDC out of it when it's alarming but doesn't turn on a relay. I then looked at amperage but came up empty. This isn't for live saving purposes it's just to turn off a fan so it doesn't feed a fire.
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using the interlok wire on a smoke detector 1
- Thread starter eric34
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MacGyverS2000
Electrical
I would consider anything that modifies (or taps off of) the wiring for a smoke detector to fall under the same rules as a life-saving device. In short, don't do it. If you screw up the circuit (and the fact that you're asking how to do it says there's a good chance you'll make a mistake that could go unnoticed), people could die.
Dan - Owner
Dan - Owner
The four AC-powered smoke alarms in my house are all interconnected with the usual extra wire. This extra wire is also connected to a special relay that triggers the alarm system if the alarm is armed (when we're not home).
This 'special relay' was purchased from the electrical supply house that sold me the smoke alarms. In the event that you can't find such a relay for your particular brand and model of smoke alarms, then it isn't really the end of the world to replace the smoke alarms as well (assuming that they're the normal $10 variety).
You'll still need to be lucky because you'll need the 14-3 wire to not just run between the smoke alarms, but also back to the panel (for example) where you could install the relay. Most of the time they'll have installed 14-2 to the first detector, and then 14-3 the rest of the way.
PS: Reading between the lines, I assume that this isn't a 'home owner' question.
This 'special relay' was purchased from the electrical supply house that sold me the smoke alarms. In the event that you can't find such a relay for your particular brand and model of smoke alarms, then it isn't really the end of the world to replace the smoke alarms as well (assuming that they're the normal $10 variety).
You'll still need to be lucky because you'll need the 14-3 wire to not just run between the smoke alarms, but also back to the panel (for example) where you could install the relay. Most of the time they'll have installed 14-2 to the first detector, and then 14-3 the rest of the way.
PS: Reading between the lines, I assume that this isn't a 'home owner' question.
Addressing Dan's point: The 'special relay' is designed and built for this sort of purpose and I believe it's made by the same company that makes the detectors themselves.
But for your application, you might have to have the 'special relay' control another relay to kill the circuit. Or use those (rarely used) circuit breakers that have a low voltage control line.
But for your application, you might have to have the 'special relay' control another relay to kill the circuit. Or use those (rarely used) circuit breakers that have a low voltage control line.
If this is for a legally-required fire detection/control system, you cannot just go wiring up smoke detectors to fan controls. I believe you will need a UL-approved fire alarm panel, or at the least, detectors approved for the intended application.
I suggest you post a more detailed question, including the building occupancy in the NFPA Code Issues forum on this site.
This is a situation where the legal/code issues trump any clever engineering solutions.
I suggest you post a more detailed question, including the building occupancy in the NFPA Code Issues forum on this site.
This is a situation where the legal/code issues trump any clever engineering solutions.
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I saw something about how the fire-safety boffins have recently (five years ago?) decided that it might be best to provide maximum air flow to a burning building so that the people can have enough breathable air to escape (as opposed to being suffocated). I guess this hasn't trickled down to the building codes yet.
DonPhillips
Structural
Smoke control in buildings have been in the building codes for years.
Don Phillips
Don Phillips
DonPhillips
Structural
There are duct-mounted smoke detectors that are designed to shut down fans. These are typically required on the return air side of a air handler or fan that moves over 2000 cfm of air.
Don Phillips
Don Phillips
This is usually for a commercial application were the Fire Marshall is asking for a fan cut off switch when the line voltage smokes go off. You should be able to pick up a UL Listed fan cut off relay or switch depending on who you are talking to. Its straight forward to install.
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