Need help on wiring light unit. Have three plug-ins inside unit. One for light , one for fan , and one for heater. Have three cables coming into unit. All three cables are 2 wire with ground wire. Black wire , white wire, and ground in each cable. One cable goes to a junction box and other two cables come from wall switches. Light plug has one blue and one white wire. Fan plug has one black and one white wire. Heater plug has one red and one white wire. How are the three cables wired to the plugs and ground.Furnace quit working after first attempt.

  • Can you post photos of the insides of the boxes in question? Dec 22 '17 at 1:46
  • We need more information. Where is this junction box in relation to the switch box? Does the switch box have full time power from 15-amp circuit? Is there a thermostat on the wall? Are all of he cables in the fan assembly 14-guage wire? Is there a separate timer switch location for the heat?
    – Paul Logan
    Dec 22 '17 at 7:13
  • Thanks for your help.The junction box is in the attic, right next to the exhaust fan. It has 4 cables coming into it. One from exhaust fan , one from outlet circuit and 2 others from the old 2-wire wiring.The switch box is on wall going into bathroom. It has a 20 amp circuit breaker with full power. Three switches in this box. Has a black and white cable coming into this box. There is a black and white cables going into exhaust fan in attic.Wires are mixture of 14 and 12 gauge wire. There is a separate thermostat for the furnace with timer. Seems to be on same circuit.
    – william
    Dec 22 '17 at 16:52

Not being there, it is hard to say for sure. But a fair guess is the the J-box wiring takes care of the heat. This wiring includes the wall stat/timer. (Hopefully this is the 12-gauge wire.) The other two cables take care of light and exhaust fan. So: j-box cable to red and white in fan. The other two, take your pick, color to color.

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