I'm in Northern Virginia and hoping to get my furnace wired up to plug into my generator. I talked to an electrician about a transfer switch a couple of months ago but he was booked up and I didn't follow up, shame on me.

Storm is coming tonight and ice + long term sub freezing temps means I want to figure this out today. Pic below of the furnace hard wired into 110 going to a dedicated breaker. In the event of an outrage, could I simply cut the breaker, cut the wire, and splice into an extension cord to run the furnace and blower? The thermostat wires also run out of the furnace so that should get power.

Current comes in from the top of that switch box. The wire to the left powers a standard 2 outlet plug for a humidifier and electrostatic air cleaner that I don't use. Wire to the right goes into the furnace.

Gas heater and the wire coming out of the switch box to the right is just control/fan power? No need to cut the wire.

Turn off the breaker and then open the switch box and unwire it. That's where you'd connect an extension cord to the wire going to the right. Add some temporary wirenuts to isolate the breaker supply for good measure.

SweaterVest said:

---

I'm in Northern Virginia and hoping to get my furnace wired up to plug into my generator. I talked to an electrician about a transfer switch a couple of months ago but he was booked up and I didn't follow up, shame on me.

Storm is coming tonight and ice + long term sub freezing temps means I want to figure this out today. Pic below of the furnace hard wired into 110 going to a dedicated breaker. In the event of an outrage, could I simply cut the breaker, cut the wire, and splice into an extension cord to run the furnace and blower? The thermostat wires also run out of the furnace so that should get power.

Current comes in from the top of that switch box. The wire to the left powers a standard 2 outlet plug for a humidifier and electrostatic air cleaner that I don't use. Wire to the right goes into the furnace.

---

If the wire to the right feeds the furnace blower and control board you could cut or disconnect from switch and add a male plug end like this

https://www.lowes.com/pd/Eaton-15A-125V-Heavy-Duty-Vinyl-Plug-YL/1002943706


Then it will plug into an extension cord ran from the generator. Keep in mind some blower motors pull 7-10 amps depending on size and age. Make sure your cord is heavy enough for the distance from the generator


If you want to get fancy, add another single gang box with an outlet that is wired to that switch and your plug will connect back to that if it is not plugged to the generator


"The wire to the left powers a standard 2 outlet plug for a humidifier and electrostatic"

Is this outlet controlled by the switch ?

Or is it always hot even when the switch is off ?

Thanks Ben and JP. I suppose if I disconnect the wires from the switch box and install a male connector I could just leave it that way and plug the connector into the 110 outlet that is powered by the wire coming out the left side of the switch box, at least until I have the transfer switch installed.

Yes, it's a gas furnace and I believe that is the only power going to the unit. The only other wires coming out are low voltage, I believe just for the thermostat.

SweaterVest said:

---

Thanks Ben and JP. I suppose if I disconnect the wires from the switch box and install a male connector I could just leave it that way and plug the connector into the 110 outlet that is powered by the wire coming out the left side of the switch box, at least until I have the transfer switch installed.

Yes, it's a gas furnace and I believe that is the only power going to the unit. The only other wires coming out are low voltage, I believe just for the thermostat.

---

You could do that. Then your furnace is either only plugged into the breaker or the generator. I'm assuming the outlet is also supplied by the same breaker? If so, when you unwire the switch, you'll need to rewire the outlet to get power from the breaker.

You could also convert the switch to this





The switch is there for a service break so tech can kill power without having to go back to the breaker box. I have seen it both ways either with switch or with a male plug to create the service break depending on how the electrician set it up.

Yeah, that's a better setup.

Just backfeed your panel through your dryer plug and make sure your main breaker is off. Then you can pick and choose what circuits you want to get power based on how big your generator is.

Thought about that but I'd have to make a big ass cable to run from my generator down through a window in my basement, probably a 60-70' run, and lock my basement down so the kids couldnt get down there and mess with anything. Would you just do that with a 12g extension cord with a male dryer connector on one end and 220 generator connector on the other?

Just cranked my 800 kw up yesterday to make sure it runs and have 15 gallons of ethanol free gas so I'm ready to roll. 4 120v and one 220v receptacles so that should be good enough for me.

Depends on the amperage of the circuit from the generator

20a=#12
30a=#10
50a=#8

I bought a 50' roll of 10 gauge and made a few adapters so I can use it as an extension cord on my welder as well. I have since graduated to a much bigger generator and installed a box tied straight to a 50 amp breaker that it plugs into and use 50 amp camper extension cords.