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Posted By: watersparkfalls Wire sizing - 10/19/21 11:27 AM
Question about what is considered control wiring…My lead JW is using 14 AWG to control the coil for a starter and heaters of a blower reel/exhaust in a mechanic shop. Basically it’s an interlock to make sure fan is on when the exhaust hose is being used on a running car in the shop. Since this was added after motor disco and reel switches were wired…He’s mounting the starters and piping over to the reel circuit using 14 gauge even though they are fed with 2.0 amp circuit, he says they are control circuits. Is this code compliment? I feel like control wiring is actually for factory assembled panels…but I don’t have much/if any experience with them.

Thanks in advance,
H20
Posted By: gfretwell Re: Wire sizing - 10/22/21 02:12 AM
This is probably a 725 class 1 circuit and the short answer is you usually use chapter 3 wiring methods. There is no code issue with garden variety 14 ga THHN an an appropriate raceway or even tray cable (becoming popular for the control cable on HVAC mini splits). You could use smaller wire tho. 16ga seems popular for this stuff and my old company had purpose built cables using 300v 18 ga that was a sort of "junior" THHN (PVC with a slippery skin).
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