I need to run smoke/co detectors that meet the new building codes in Danbury CT. I also am trying to connect them to my hard wired alarm system. I found a smoke/CO detector that has relay outputs to connect to your alarm system GN. They indicated the low voltage alarm contact wiring needs to be atleast .25" away from the line voltage (120VAC) to meet NEC code but I should check with my local codes. Does this 1/4" spacing sound correct? does anyone know of a low voltage (12VDC) smoke/CO detector that has a sounder and form A,B,or C outputs for both the smoke and CO side?
Most interconnected CO, Smoke or combo units, will have one wire that allows a signal to be sent between units, to sound them, which is the Red wire usually for the 14/3 that they are using to power & have a signal wire.
As long as the LV wire is a part of that unit, it is fine to have it in the same box, or the same conduit. It is when you say run the Doorbell button wire, through conduit for say the front entry light, then you have an issue, because they are not for the same circuit.
Most new CO/Smoke units, no longer use the third wire. They will use what is called a "Mesh" network. Some also have the choice of either the third wire or the Mesh network for com's to the alarm panel.
It does help to know the model & manufacturer of the panel & the sensors in question.
I'm using a Vista-128BPT and GN-503FF smoke/CO detectors by Gentex. Tech support indicated the 1/4 spacing inside the same box met NEC standard. I was planning on using 4/18 firewire to run back to the alarm panel from the smoke detector gang box.
There really is no NEC standard in this case. It may be manufacturer recommendation on how you run the two different circuits into the box that the device attaches to. You do not use 4/18 firewire for this. You just need to follow what the manufacturer recommends for wiring the devices to their panel.
Usually it is just Bell wire or #18 CL-2 Inside wall Stranded wire with a outer jacket on it, that is used.
The only thing about NEC that is required, is that the LV wiring has to control the same circuit that it is going through the same conduit. In the case of Smoke, CO, Personnel sensors, Heat Sensors, there is nothing out there that states that there must be a 1/4" separation.
Now if they are separate systems, say CATV, Telephone lines running into a house or building. Then they need to be at least no less then 1 foot distance from the High voltage electrical drop going into or exiting that structure. Some like to keep them apart by at least 2 feet, just for grins.
Once you place the unit onto the junction box, the 120vAC & signal wires are going to be against each other anyways, so it really will not make any difference.
Now if you want to do it correct, you need to use the Red jacketed wire that is used for alarm systems, so that the next guy/gal that comes along, knows that line is for only the alarm system, not for a doorbell or something else, if they find it in the attic, basement, crawlspace or garage.
Usually it is just Bell wire or #18 CL-2 Inside wall Stranded wire with a outer jacket on it, that is used.
The only thing about NEC that is required, is that the LV wiring has to control the same circuit that it is going through the same conduit. In the case of Smoke, CO, Personnel sensors, Heat Sensors, there is nothing out there that states that there must be a 1/4" separation.
If enclosed in the same raceway or box.........there may be something about the insulation having the same voltage rating..
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