Is it common for heat detectors to have only 2 terminals? We are installing heat detectors throughout the bulding; some are addressable and some with an EOL but I cant stop from wondering why do they only have 2 terminals. I remember a while back when I did heat detectors there were 4 terminals on the back of the heat detector, 2 were used for the wire comming in and the other 2 terminals for the wires going to the next heat detector. And if this is common to have only 2 terminals then whats the best way to wire the heat detector? Some of the guys were using pigtails and i thought that was wrong.
Heat Detector connection
- Thread starter ianis
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- Location
- Massachusetts
I have to imagine if there are only two terminals they are of the 'pressure plate' type with a square washer under the screw head that will accept one conductor on each side of the screw.
- Location
- New Jersey
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- Journeyman Electrician
They only require 2 wires, wired in parallel to each device, hence two terminals. If they use an EOL resistor then in normal operation the FAP is reading the resistance of that resistor at the end of the circuit. In an alarm condition the device closes across the two terminals and the FAP reads this as a closed circuit. If a wire breaks or is removed from a device the circuit is now open and the FAP will read this as a trouble alarm. Pigtailing in this type of system is not permitted since a device could be removed without the system seeing it as a trouble.
- Location
- Massachusetts
I know we are kind of saying the same thing but I can not really agree with putting it this way.
The device can not be supervised (other then a missing address) with just two conductors.
The heat will have to have four distinct conductors connected to it and this is as you pointed out a 'no pigtailing' and 'no looping' application.
Four wires can be connected to two terminals assuming they are the correct terminal type.
infinity said:
The device can not be supervised (other then a missing address) with just two conductors.
The heat will have to have four distinct conductors connected to it and this is as you pointed out a 'no pigtailing' and 'no looping' application.
Four wires can be connected to two terminals assuming they are the correct terminal type.
ianis said:
If the detectors are in fact addressable there is no issue with pigtailing and the device may well only have two connection points..................... If you have a class A loop with an EOL then no you can not pigtail and your wiring needs to be supervised.
But you can't have it both ways unless you're working on some type of system with which I am not familiar.
My guess is that you have addressable heat detectors.
Is it possible to have both types in the same building? Maybe an older portion that is non-addressible, so it needs the EOL resisitors, and a new, addressable portion for the new heats?
Seems to me I've seen this done in the past, but can't put my finger on where I say it right now. Getting old sucks... my memory was the second thing to go.
Seems to me I've seen this done in the past, but can't put my finger on where I say it right now. Getting old sucks... my memory was the second thing to go.
gadfly56
Senior Member
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- New Jersey
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- Professional Engineer, Fire & Life Safety
480sparky said:
Interesting thread...
I am just about to start installing a boat load of initiating devices ....we have addressable heat detectors as well as 2-wire (non-addressable) models....haven't recieved the entire shipment yet, so I don't know how many modules will be included ~ whatever the engineered count was to be, it will be wrong due to numerous changes in the building
The 2-wire heats are System Sensor 5600's:
(Don't click..it doesn't enlarge :roll
The smokes and other apparatus seems to be Notifier (website seems to be down, BTW):
I am just about to start installing a boat load of initiating devices ....we have addressable heat detectors as well as 2-wire (non-addressable) models....haven't recieved the entire shipment yet, so I don't know how many modules will be included ~ whatever the engineered count was to be, it will be wrong due to numerous changes in the building
The 2-wire heats are System Sensor 5600's:
(Don't click..it doesn't enlarge :roll
The smokes and other apparatus seems to be Notifier (website seems to be down, BTW):
mdshunk
Senior Member
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- Right here.
Yeah, I noticed that earlier today. The whole Honeywell family of fire alarm stuff seems to be down. I needed to download a FireLite paper, and it was down at about 4pm Sat. Still down at 2am Sun.celtic said:
gadfly56
Senior Member
- Location
- New Jersey
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- Professional Engineer, Fire & Life Safety
celtic said:
It's odd to mix addressable and non-addressable in a new install. Are you (or really, the designer) sure about this? The only reason to go non-addressable in this case would be if some of the new H/D's were going somewhere where the ambient temperature was below 32F or above 100F. Or if there were renovations to part of the building serviced by the original install and they were too far/too inconvienient for the addressable loop.
mdshunk
Senior Member
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In an existing building, we do this all the time. Gives the owner time to budget for replacement of the non-addressable equipment later on. It does strike me as a bit odd for a new construction too.gadfly56 said:
I am 100% sure....sorted through a dozen or so boxes matching the parts to the Bill of Materials....we have LOTS of modules to install now w/seperate 24v feedsgadfly56 said:
We have addressable units in a comm. kit.; non-addressable in the "fan loft" (attic mech room)gadfly56 said:
All new work.
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