Generator control wires

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frofro19

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VA.
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Master Electrician
Can thermostat wire such as 18/8 be ran in a crawl space and then into a unfinished basement not in conduit? This would be for the control wires going to a 24 Generac generator. It goes from the crawl to the unfinished basement part and would be a little difficult to run the control wires in conduit with everything it has to go around.
 
I don't believe that T-stat wire is rated for the 120/240v that is part of the control wiring.

There is a generator-specific cable available, or you can use regular wire in a flex like LNMF.
 
A lot of installers don’t realize Generac uses 120 and 240 volt controls, along with 12 vdc. I imagine the reason Generac switched from 240 volt controls and battery charger, to 120 volt, because a lot of them were being installed on 120/208 volt systems. The generator controls the transferswitch, instead of the transferswitch controlling the generator like most major manufacturers.
 
LarryFine said:
I don't believe that T-stat wire is rated for the 120/240v that is part of the control wiring.

There is a generator-specific cable available, or you can use regular wire in a flex like LNMF.
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I usually run 14 thhn/thwn wires in conduit, but this particular one is over 100 feet and has a lot of obstacles to go around. Need some tray cable wire but don't have enough time to order so maybe conduit it is.
 
Just make sure you protect those wires properly. I have an incident where the exciter windings got fried because the generator output cables, the control cables, and the exciter wiring were lumped! Vibrations on the machine damaged the cable insulations and 240V jumped unto the exciter circuitry! It's one of those cheap clones that are sold by you-know-who!
 
frofro19 said:
Can thermostat wire such as 18/8 be ran in a crawl space and then into a unfinished basement not in conduit? This would be for the control wires going to a 24 Generac generator. It goes from the crawl to the unfinished basement part and would be a little difficult to run the control wires in conduit with everything it has to go around.
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Absolutely NO. Before I started using Generac composite cable from https://www.cablemasterpowercords.com/ I would use SER for the power and 2 runs of 14/3 for control wires inside the house then transform to THWN outside the house. The control wires are 12VDC and 240/120VAC so you cannot use CL-2 cable.
 
I'm assuming it the t-stat wiring you are taking about is not the generator control, but the load shedding control. I my installation there is t-stat style wiring running from the Generac control panel outside to the air conditioner controls (2 conductor). This cable is tied in series with the A/C thermostat cable in the furnace room. It just opens the A/C thermostat controls to shut down the outside compressor. All the rest of the generator/transfer switch control wiring is inside either in conduit or seal tight.

If you run any wiring unprotected in a crawl space, I would be worried about mice. They love to chew the insulation on wires.
 
RCC1 said:
I'm assuming it the t-stat wiring you are taking about is not the generator control, but the load shedding control. I my installation there is t-stat style wiring running from the Generac control panel outside to the air conditioner controls (2 conductor). This cable is tied in series with the A/C thermostat cable in the furnace room. It just opens the A/C thermostat controls to shut down the outside compressor. All the rest of the generator/transfer switch control wiring is inside either in conduit or seal tight.

If you run any wiring unprotected in a crawl space, I would be worried about mice. They love to chew the insulation on wires.
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Good point, but the OP said it was going to the generator, the load shed comes from the transferswitch if I’m not mistaken.
 
hillbilly1 said:
Good point, but the OP said it was going to the generator, the load shed comes from the transferswitch if I’m not mistaken.
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Yes, I was referring to the control wires from the generator to the ATS. I will be running a 2 conductor 18 guage thermostat wire from the ac load shed in ATS to the ac unit which has 134 LRA. But opt in this case to run ser for generator power and 2 sets of 14/3 UF for control wiring.
 
14/3 is hack work, kinda big to land in those push terminals.
Just get some FNMLT conduit or Greenfield and pull in some 16 or 18 ga. THHN/THWN or MTW
 
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