My home air conditioner needed a new start/run cap. Replacing it was pretty simple since I have a background in electronics even though not specifically in HVAC.
One of the spade terminals (a .250 Fast-On, if you care) needs to be replaced. The wire it connects to us already tighter than I like so I want to replace it with a slightly longer one so it has a little slack instead of being drawn tight.
Here’s the thing, and my question: The wires to this cap are 12 gauge stranded but have much thicker insulation than anything I am used to. I want to do it right, can anyone with experience tell me what I need to search for/order?
Google searches about the AC wiring lead me to countless sites telling me how to change the cap, but all of them just tell me to hook up to the original wires. Nothing about the specs on those wires. I note that on almost all the wiring inside the unit the insulation is what I would consider “normal” except for the ones in the vicinity (i.e. attached to) the compressor.
I couldn’t find anything definitive, but I’m pretty sure that the compressor / capacitor wires are designed to be both heavy gauge and flexible, so the insulation is different from the usual stiff PVC stuff.
I would think that 12 Gauge THHN would be fine, if you make it long enough to form a loop, so that there is no strain on the connection.
Have you checked all the way back to where it connects to the motor/board/relay? Often times in home AC units I see wires zip tied together or zip tied to the frame. You may be able to undo one of those zip ties and get some more slack. Especially, if you’re just looking for another inch of two.
This may not be of any help to you, but you want to look for connectors that have 600 volt insulation. This would be the standard for this type of wiring. Some spade-type connectors have only 300 volt insulation, which is appropriate for CL3 wiring systems (300 volt) per NEC.
I have 12 THHN so if nothing definitive comes up that’s what I’ll use.
I have checked all the way back. This wire goes directly from the cap to the contactor with no bundle at all. Unlike almost every other wire in the thing, of course.
My connectors have no insulation on them so I don’t have to worry about that, but thank you for pointing it out since I will have to replace them with something.
If you just want to add 6" or so of THHN to the existing wire, put it on the end furthest away from the compressor. I’d also secure it so it isn’t subject to mechanical damage such as rubbing from vibration.