Why have reversing relays and supervision relays?
- Thread starter Mr Spock
- Start date
here's my impression (just planning my house, so having to learn about it). folks can correct me if I am wrong.
reversing relay - you need this if you have more than one smoke alarm and they aren't all daisy chained together on one zone. without this, when one alarm goes off, none of the other alarms would go off
supervision relay - you need this because a smoke alarm is normally open - meaning you can't put an 1K ohm resistor on it. Without the power supervision relay, if you accidentally cut the smoke alarm wire, you'd have no idea that something was faulty. since 4 wire smokes don't have back up batteries, you wouldn't even get a low battery warning. So if there was a fire, the alarm wouldn't go off. By having the power supervision relay, the panel knows if the power to the alarm gets interrupted.
reversing relay - you need this if you have more than one smoke alarm and they aren't all daisy chained together on one zone. without this, when one alarm goes off, none of the other alarms would go off
supervision relay - you need this because a smoke alarm is normally open - meaning you can't put an 1K ohm resistor on it. Without the power supervision relay, if you accidentally cut the smoke alarm wire, you'd have no idea that something was faulty. since 4 wire smokes don't have back up batteries, you wouldn't even get a low battery warning. So if there was a fire, the alarm wouldn't go off. By having the power supervision relay, the panel knows if the power to the alarm gets interrupted.
Sandpiper
Active Member
dsiroky has it right. Said another way:
End-of-line resistors are necessary for integrity monitoring of the signal circuit for 4-wire smokes. End-of-line relays (supervision relays) are necessary for integrity monitoring of the power circuit for 4-wire smokes. Reversing relays are necessary for those 4-wire smoke circuits in order to simultaneously activate the sounders in the smokes on the circuit. Note that the reversing relay can only be used for smokes designed for the reversing relay. (Not all smoke have this feature.)
End-of-line resistors are necessary for integrity monitoring of the signal circuit for 4-wire smokes. End-of-line relays (supervision relays) are necessary for integrity monitoring of the power circuit for 4-wire smokes. Reversing relays are necessary for those 4-wire smoke circuits in order to simultaneously activate the sounders in the smokes on the circuit. Note that the reversing relay can only be used for smokes designed for the reversing relay. (Not all smoke have this feature.)
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