Power Outage is Expected, Hooking up a Generator

If I understand your scenario correctly, the cord connecting the genset to this outlet will be a grounded plug at both ends, instead of the common plug and receptacle layout. So, probably not going to work. You may be backfeeding the entire house with this scheme.

This receptacle you describe, is anything plugged into it? If yes, it would be usual to be the furnace… this arrangement lends itself easily to unplug the pigtail from the fixed outlet and then plug that into your extension cord from the genset.

Do not feed the generator receptacle from the generator. It can feed back into the entire electrical system grid. The HV transformers work both ways.

19,200 volts steps down to 120 volts and 120 volts can be stepped up to 19,200 by the same transformer. The result could be back-feeding the 120 volts into the high voltage wires, causing a dangerous voltage to linemen working on a supposedly dead utility line.

If you must power the furnace, isolate the generator from the house wiring. Consult a licensed electrician for advice and further guidance. It is simple to do but since you have no electrical experience, it is better safe than sorry.

Thanks, I’ll find another way to stay warm.

Labyguy

Being a lazy guy, I would connect my special made double plug extension cord to your furnace outlet. Of course, throw off the furnace breaker, and for good measure, open the main circuit breaker before you plug in the cord. Plug the cord in after the breakers are off. Then start the generator.

Reverse the steps, stop generator, unplug cord, turn breakers back on.

Watch your neighbors to decide if the electric is back. Maybe 8 power outages and counting since 1984 or so. I use the dryer 220 receptacle and feed the entire house. I then decide what gets powered if the load is too high, such as running both AC units. First 1, then the other.

People who can’t follow instructions should probably not do this. :)

Another question, what if I open my main breaker on my electrical panel, would that isolate my home from the grid???

Labyguy

Yes.

It would isolate you from the main panel, depending on the type of system you have but everything below the main will have power. Turn off all breakers, before connecting the generator. then turn on only what you need, if not, expect an instant overload on the generator.

You may be required to install a grounding rod, according to the NEC, or local regulations. Check with the local AHJ(Authoriy Having Jurisdiction).

Be safe, not sorry.

Usually there is a ground rod that is hard-wired to the panel ground bus that is independent of any breakers. Any generator connection should include a ground wire connection.

If you intend to feed the genset into the house wiring and not just power the appliance directly, then, in addition to grounding the genset, you should also remove the neutral tie in the genset itself. The reason is that the only place the neutral and ground should be tied is at the mains panel. This might be overkill for an emergency hookup, but if you connect the hot(s) neutral and ground wires to house wiring, then you need to isolate them from each other except at the mains panel.

Somebody correct me if I'm wrong.

You are correct, if the neutral of the generator is bonded to the generator frame, and even if you don’t intentionally ground the generator, then you have two grounds on your power system. I suppose you could verify this easily with an ohmmeter. As you suggest, removing this ground link in the generator should be the easiest way to avoid double grounding the system.

From an engineering standpoint, the power system should only have 1 ground. If you connect your correctly sized ground wire between your generator and panel (at least same size as current carry conductor), the system is grounded. The available fault current on most generators is significantly lower than your utility supply, so the short time rating of your #14-#10 wire is plenty to trip the generator main or branch breaker.

If you run the generator as the sole supply for your appliances, such as on extension cords, then you need to ground the generator separately. You need a good ground to serve as a fault return path.

What you don’t want is a power system with two power system grounds on it, especially if one of your return conductors is intentionally earthed, like in the US. That is why you do not earth the neutral at a subpanel, for example. There are a number of possible faults where two grounds can split fault current, so the fault current bypasses the main breakers, leading to misoperation of circuit protection, especially backup protection provided by main breakers.

Here is our favorite AI rundown on this:

• Increased Shock Risk: When there are multiple, unbonded ground points, electricity may use metal plumbing, conduits, or even a person as a path to find the "lowest potential" ground, resulting in electric shocks when touching appliances or pipes.
• Fire Hazard: Improper grounding can cause electrical panels or wiring to overheat, increasing the risk of fire.
• Failed Circuit Protection: If ground and neutral are improperly connected at a subpanel or outlet, a fault may not trip the circuit breaker, allowing electricity to continue to flow through the casing of an appliance.

We could use some specific examples for points 2 or 3, but I suspect they exist. The first is good enough for me.

If your power goes out anywhere, anytime, turn off your mains breaker.

It prevents double ended dildos-of-death power cords from killing linemen and it also prevents the power surges etc from killing your household appliances.

I replaced quite a few kitchen appliances that were killed by the power coming back on, spotty, brown-out or otherwise. Fortunately they weren't mine.

You hope that all your neighbors don’t do the same thing. :)