2 generators simultaneously for backup power

The beautiful theory: Use one generator on one leg, Use the other generator on the other leg.

The murder of a beautiful theory by a gang of Brutal Facts.

When you are adding batteries, in series,6+6 = 12

But when you are adding generators it only works that way if they are in perfect phase with each other.

So using two 120 volt generators you can ONLY operate 120 volt stuff NOT 240 volt stuff.

Second, IF you have say 30 amp wiring and 3000 watt generators well, one leg,works great.. IF they are in phase or nearly so..Works great

But when they move 180 degrees out of phase the neutral wire is carrying BOTH legs,Overheat and fire may result.

A disadvantage of heavily loading a single phase is fuel economy down the tubes. 3,300 watts of 120 loads the generator just as much as 4000 watts of 240. I have a 12-wire connection on the KATO

wnjj wrote:

KD4UPL wrote:
The neutral doesn't touch the breaker.
No, you probably wouldn't overload the neutral because each gen. would have it's own.
It's still a terrible idea that would not provide 240v power.

The concern is over a shared neutral that may be in the house. Shared neutrals were sometimes used to save wire with the knowledge that the 2 hots were on L1 and L2 so canceled each other's neutral current. If you were to effectively power both in phase, the neutral would carry 2x its rated load.

Ditto. Contractors who build a lot of houses in planned subs do this often to save pulling extra wire or if, for example, multiple circuits are being run to the same destination. In my case, I ran this exact circuit for my basement plugs so I could plug in two space heaters into two adjacent receptacles in my basement, but fed off two separate circuits. I also used this trick to pull one piece of wire to power my basement fridge and deep freezer (again, two separate circuits, one wire).

It's this type of arrangement that can overload if the two legs of the power feed aren't in-phase with each other. If, for example, all three wires in the wire are 12 gauge (rated for 15A) and both circuits are carrying a 10A load, the neutral is carrying 0A. If, however, the two circuits are out of phase (actually in-phase with each other), the neutral would be forced to carry the load of BOTH circuits; in this example 20A.

Running two generators into the same panel is a recipe for disaster on several levels.

LOTS of Generator info on the link below.

If "Professor95" still monitors this thread, no doubt he would love to chime in.
Check his location - wealth of electrical talent in your backyard!

Several posters in your neck of the woods have powered their homes with Champion gens, including the Prof for several days - including 220V (although *not* the way you envisioned, LOL!)

"Chinese Gensets Info" - beginning of thread.

This should get you at least close to the end of the thread

It's *not* limited to the 3000watt gens -or- Champion.
Lots of good stuff in those 996 pages!..:W

There is also another lengthy thread with Champion *Inverter* gen info.

.

Mex, as regards the Champion 3500/4000, I've metered it under real-world conditions, and 120v-wise it performs perfectly: 125v at the gennie with no load, 120v at gennie with 20a load, 116 at the TT with 20a load.

Never metered the 240, maybe that's the falldown.

KD4UPL wrote:
The neutral doesn't touch the breaker.
No, you probably wouldn't overload the neutral because each gen. would have it's own.
It's still a terrible idea that would not provide 240v power.

The concern is over a shared neutral that may be in the house. Shared neutrals were sometimes used to save wire with the knowledge that the 2 hots were on L1 and L2 so canceled each other's neutral current. If you were to effectively power both in phase, the neutral would carry 2x its rated load.

Pre-proven disaster ready to pounce. Paralleling generators is an artform. The generators must be similar. Same type of voltage regulator. Neutrals connected. An incandescent lamp connected parallel with both L1 Phases. Speed MUST BE EXACT between the two prime movers. 60 Hz right on the nose.

When the generators are out of phase the light bulb will light up. Slowly but surely the light bulb will dim then go out. Count the seconds the light is out. Wait for another lighting of the bulb and when it goes out again count to one half the total time the lamp remained off the first time.

If the lamp stayed off 6-seconds the first time count to three then trip the main switch to on. The generators are paralleled. Instrumentation is mandatory. Two ammeters are mandatory.

Fun & Games will begin if the genertors are not identical in both capacity and govenor response. One willead the other will lag. One or both will start surging.

You don't really want to get too deep into all this do you?

Dual voltage generators NEVER offer a 120vac output anywhere near the advertised wattage of the machine. If you operate dual voltage machine for max 120 volt output get a transformer.

The neutral doesn't touch the breaker.
No, you probably wouldn't overload the neutral because each gen. would have it's own.
It's still a terrible idea that would not provide 240v power.

kaydeejay wrote:
Where did the OP say the neutral would be shared?
Two gens with two neutrals wired to the panel would run all 120V appliances just fine.
It's the 240V stuff that would make it just too complicated and prone to mistakes.

The OP said, " i would also purchase a second non-nverter gennie and use it to power one leg of a 220 breaker, and the inverter gennie to power the other leg of a 220, both wired to neutral and ground."

If he is wiring these two generators to one 220 brkr, is there not but one neutral leaving the breaker? :?

BurbMan wrote:
Even 120v circuits....you could have a pair of 12ov circuits wired out phase with a shared neutral...the circuits would work fine powered in this manner, but you would severely overload the neutral with twice the current it was designed for and probably start a fire. As was stated, 220v appliances would likely fry themselves if powered with 2 inputs on the same phase. Plus you would need 2 transfer switches. This is a BAD idea no matter how you slice it.

The Champions are cheap enough, just buy a second one and run the parallel, this way you have one power cource to the panel, even though 22v stuff wont work. If you need power to 220v stuff then you need a bigger generator.

Where did the OP say the neutral would be shared?
Two gens with two neutrals wired to the panel would run all 120V appliances just fine.
It's the 240V stuff that would make it just too complicated and prone to mistakes.