I need to cut out the existing wire and splice on new wire since the insulation is torn up beyond repair (shorted out the 5A fuse) , obviously a Temp repair until the part can be ordered

  • Does the float switch run at mains voltage, or at 24VAC? Is it a built-in part of the HVAC unit, or external to it for that matter? – ThreePhaseEel Jan 27 '19 at 23:50
  • it is contained within the unit. I assume its 24vac. existing wire appears to be 16-20awg but I don't know where or what type of wire to use safely – dave Jan 28 '19 at 0:19
  • Can you find a wiring diagram or make & model number for your HVAC unit and post it? – ThreePhaseEel Jan 28 '19 at 1:30
  • for the 5 amp fuse can I just use a car fuse? I think the wire is #20 – dave Jan 28 '19 at 5:42
  • I take it the 5A fuse is on the control board? – ThreePhaseEel Jan 28 '19 at 12:36

I would use an 18AWG multi-rated TFFN/AWM/MTW here

The most commonly available wire that I can reasonably say is usable for this application would be an 18AWG wire that is multi-rated as TFFN (fixture wire), AWM (appliance wiring material), and MTW (machine tool wire). This wire is generally a stranded copper, with PVC insulation rated for 105°C in appliance (AWM) applications, and should be available from any competent electrical supply house (as it's also used for internal wiring in light fixtures, hence the name "fixture wire").

UL 486 listed wirenuts or insulated butt crimp splices suitable for connecting 18AWG to 20AWG (the latter applied using an appropriate crimp tool) should be used to splice the patch-wire into the float switch wiring, by the way. You are correct, though, that the low-voltage fuses used on HVAC control boards are typically of an ATO (automotive) type (rated for 32VDC/VAC), so replacing the fuse with a plug-in automotive type of the same amp rating will work.

  • thanks. I didn't change the wire I just taped all the scuffed insulation/wire . in two places I had to cut the wire and re-splice the wire to itself. I added the 5A fuse I bought at advanced auto parts. it works but after about 5 minutes the double 60 breaker trips. you think that's from the damaged float switch wire or what? – dave Jan 30 '19 at 1:36
  • @dave -- can you post a new question, with the make/model + wiring diagram of your unit? – ThreePhaseEel Jan 30 '19 at 1:50
  • where can I find a wiring diagram, I think there is one taped to the back of the control panel is that it? – dave Jan 30 '19 at 2:13
  • @dave -- yeah, that sounds about right -- if you can get a clear photo of that and put it in your new question, that'd be awesome – ThreePhaseEel Jan 30 '19 at 2:50
  • I posted the question but images are at imgbb name 'blaze2248' – dave Jan 30 '19 at 12:50

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