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When running a portable generator to provide power to my furnace, sump pumps and television etc during an extended power outage, can I simply run a ground wire in alongside the extension cord(s), from the grounding terminal on the generator, to a water pipe grounding clamp?

The furnace has an individual transfer switch (it goes by the name "EZ Generator Switch") that receives the female side of the extension cord. The Sump Pump, TV, etc. get unplugged from the home outlets, and plugged into the other extension cords coming from the generator.

  • How are you isolating the generator running the furnace, sump pumps and TV from the normal building wiring? Unless you have hard wired those items into a generator only mode of operation it is essential that you install a proper transfer switch and interlock system. This is required by the electrical code and demanded to ensure the safety of line workers, especially in the case of an outage where your generator may be running. IT IS NOT GOOD ENOUGH TO JUST PLAN TO SHUT OFF CERTAIN POWER PANEL BREAKERS. – Michael Karas Dec 10 '16 at 20:41
  • Michael, thanks for the quick response. The furnace has a Transfer Switch, with a recessed male connector that receives the female side of the transfer switch.(Purchased on E bay under the name EZ transfer switch). Pretty cool set up.. The sump pumps and other appliances get plugged into the extension cords coming from the generator. Basically unplugging from the house outlets, and plugging into the extension cords from the generator – Duro Dec 10 '16 at 20:47
  • Does your EZ Generator Switch have a switched or an unswitched (continuous) neutral? – ThreePhaseEel Dec 10 '16 at 20:58
  • I just verified, the neutral DOES NOT get switched. It's continuous. – Duro Dec 10 '16 at 21:24
  • @Duro - Good to hear that you have a scheme in place that indicates to be relatively safe. Sounds like it could be a bit of a hassle getting it hooked up when there is an outage but at least the ancillary equipment is pluggable by extension cords. – Michael Karas Dec 11 '16 at 2:11
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Grounding isn't the problem, your neutral is

Since the EZ-Generator-Switch for your furnace has a continuous neutral and ground, I'd recommend doing nothing additional here for grounding. Your generator is already grounded through the ground connection from your house wiring to the EZ-Generator-Switch and the ground wire in the cord from the EZ-Generator-Switch to the generator.

Now, the neutral is a different problem. Portable generators bond the neutral to the ground themselves as they're intended to be used as standalone supply sources. Your house wiring also bonds the neutral to the ground at the main panel. So, not switching the neutral to your furnace between your house wiring and your generator effectively parallels the two neutral/ground bonds, which is problematic from a Code compliance/safety standpoint (a GFCI equipped generator will trip its GFCI under these circumstances, and it can have other baleful effects as well such as inadvertently energizing grounded metal objects with circulating currents).

If you wish to use this generator only for powering your important things in this (hacky, but safe) way, you can remove the neutral/ground bond wire from the generator and set it aside. However, if you do this, you'll need to replace the neutral/ground bond if you wish to use the generator for anything else. A better solution would be to switch out your existing EZ-Generator-Switch for the version with the switched neutral -- that way, the two neutral/ground bonds (your house's and the generator's) never get put in parallel.

  • Just to clarify, until I can switch out the ez transfer switch on the furnace to a switched neutral type, , if the generator is needed MORE for the other items such as lights and sump pumps, I should not try to run the furnace this way. Correct? And, once I do get the EZ Transfer Switch replaced, going back to the original question, could I ground the actual generator unit using the water pipe in the house instead of pounding in a ground rod for that generator? – Duro Dec 10 '16 at 22:38
  • @Duro -- my "anything else" is referring to using the generator as a portable generator, not a house-generator -- and you don't need to bother running an extra ground wire for the generator at all -- it's grounded by way of being plugged into grounded house wiring! – ThreePhaseEel Dec 10 '16 at 23:48

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