Aux Generator

[SJTD]

Everyone suffers a blackout once in a while. Inconvenient for us since we have tankless water heaters; two electric and one gas. Currently if the power goes out I have to run an extension cord from the inverter in the truck to the gas heater.

Been planning to get a generator; nothing too big, just enough for the gas water heater, fridge and a few lights.

I have an outlet on the back patio. When the power is out I'm thinking I can open the main breaker and plug the generator into the patio outlet to feed the house through that circuit.

Obviously have to shut off the electric water heaters and tell the womens not to run hair dryers, etc.

What am I missing other than the legalities?

[acct21]

Backfeeding isn't a great idea -- for several reasons.

You absolutely have to make sure your main panel is shut off -- or else your generator is going to attempt to backfeed your entire neighborhood. That's bad for your generator, and bad for the pole jockeys out trying to restore service. It's obviously extremely illegal to backfeed beyond your home.

In addition, you probably don't have all of your 'necessary' circuits fed from the same 120v 'leg' coming from the utility company. Your main panel is fed by separate 120v lines coming into your house -- and each leg is separated from the other at the main panel. The lines typically alternate down the breaker panel (in separate conductors called "bus bars"), which is why you need to straddle two adjacent spots in order to get 240v.



If you energize one of the legs via a generator backfeed, you will likely be disconnected from circuits on the other 120v leg (you'll just be able to connect to circuits also connected to the one bus bar that is usually supplying that outlet). Everything connected to the other bus bar will be disconnected. There isn't a straightforward way to overcome this, other than making sure all of your necessary circuits are re-arranged in the breaker box to be on the same 120v service leg. Don't know if that is feasible, or even advisable (the panel was probably balanced by the electrician that originally installed the wiring in your house, and you'd potentially be undoing that).

Get a manual transfer switch installed next to your service panel, and connect the circuits you want to energize with your generator. When you lose power, connect your generator to the transfer switch, and you'll get only the circuits you want -- nothing more, nothing less. Much safer all around.

[77Deepj20]

Yeah, don't backfeed the house with some random hookup like that. It would also require a special extension cord with two male ends on it, which is also dangerous.

A manual transfer panel is a good choice if there are only a few things you need to operate. Another option is a generator interlock kit. They use a sliding mechanical interlock bracket installed on your electrical panel.box between the main breaker and usually a 30amp 2 pole breaker installed in the panel. The 30 amp breaker is connected, via wiring, to a remote outlet box installed somewhere outside that you can hook a large cord from the generator into. This will feed the entire panel box and allow the use of almost any circuit. Obviously you will.likely have issues running an electric water heater, air conditioning or any other large single load, but is a more versatile setup than most manual transfer panels.

[SJTD]

You'll note I said "open the main breaker".

I understand about the two legs. This house was wired with the wall outlets on one leg and the overhead lights on the other. I followed that convention when I added a bedroom, bath and laundry where the gas water heater is. It only needs power for a small fan and igniter.

The other possibility is to plug the 240 output of the generator into the welder outlet in the garage. That would run the whole house including the heating.

I get that what I propose isn't the best or safest plan but I don't want to install a transfer panel or switch for something that I might need once a year. If I install solar I would do it at that time.

[acct21]

If you wired your house, then you can build a transfer switch for your gas heater for under $100. You could also relocate the breaker for that outside outlet higher up in the panel, so you can put it on an interlock with the main breaker. Pick one and revel in the satisfaction of having solved a tough problem the right way.

[TexasJ10]

A cheap transfer switch is definitely the way to go for safety and to insure that you don't overload your generator or potentially create low voltage situations that will kill motors and electronics. If you insist on doing it, make double sure the main is thrown and probably all the individual breakers other than the hopefully two dedicated circuits you need. I hope you will get a transfer switch though or consider a disconnect on your water heater with direct generator feed and direct feed to your refrigerator.