Yes, yet another generator question - Oven-Micro combo Unit Q

[CHDinCT]

With Sandy now come and gone here in CT, we lost power for five days. No property damage thank goodness. We purchased a 6400 WATT (running) generator last year just before Irene and had a generator interlock switch wired in last summer so we were able to run most circuits in the house including the well water pump and furnace (for hot water - heat with wood now). Our generator can run any of our circuits except the 50 amp stove and 50 amp combo oven/microwave.

Which brings me to the question of whether we can run the microwave unit that's part of the 50 amp oven/microwave circuit? I know that the microwave runs on 120 volts somehow. I'm thinking that the 50 amp circuit delivers two 120 volt lines to the oven/micro and the oven uses both lines while the micro only uses one of the 120 volt lines. So, could I energize the 50 amp circuit and only use the microwave unit? If not, we'll have to purchase a separate table-top microwave for when we're on generator power. Any electricians out there that can say yeah or nay? Thanks in advance

 

[sailfast]

Yes

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[cmore]

Yes, but since u probably have other devices drawing power at the same time, u might kick out the gen's beaker.

 

[CHDinCT]

Thanks - that was my gut feeling but didn't want to do something to damage the genny or anything else. And yes, we'll have to manage when to use it. Biggest draw is the well pump. I can hear the genny pull down on RPMs momentarily when it comes on. When I first start up the generator, I put the well pump on first and then let the genny stabilize before openning more circuits. We'll have to make sure the pump doesn't come on when the micro is running, so I'll just shut that one down for a few minutes.

 

[dave1949]

With 6400 watts, you should be able to run your whole house - minus those two big 50 amp loads. Your stove-microwave combo doesn't use power (except for a few watts for a clock and control panel maybe) unless you actually turn on a burner or start the microwave. So, using your microwave will only draw whatever the microwave itself actually uses, probably around 1500 watts.

If you scroll down and look to the right side of your screen, there is a list of common watts usage for households.
http://michaelbluejay.com/electricity/howmuch.html

If you have two 50 amp breakers (one for oven and one for stove-micro) you must have one heck of an oven(s?) and stove. You can probably run one stove burner on your generator, the worst that can happen is you will trip the generators circuit breaker, so what ?, that is what the breaker is there for. If that happens, turn off the load that caused it to trip and reset the breaker. Usage doesn't happen until you turn something on.

 

[Mickey_Fx]

Just adding you do need to try and balance your load between the (2) 120 legs. Most transfer switch panels have Watt meters to show how big a load each leg is carrying. Unfortunately with an interlock switch you don't have that but something could be added. Maybe to the genny itself.

I just finished wiring my transfer switch panel in yesterday. Before hand I decided which circuits to include and which leg they are connected to. Had to have some wiring changed so loads were better balanced.

 

[CHDinCT]

If you have two 50 amp breakers (one for oven and one for stove-micro) you must have one heck of an oven(s?) and stove.

Thanks for the link. The stove(top) is a totally separate unit from the oven/micro. I'll have to double check, but I think each one is running on a 50 amp line..

 

[SPYDERLK]

Thanks - that was my gut feeling but didn't want to do something to damage the genny or anything else. And yes, we'll have to manage when to use it. Biggest draw is the well pump. I can hear the genny pull down on RPMs momentarily when it comes on. When I first start up the generator, I put the well pump on first and then let the genny stabilize before openning more circuits. We'll have to make sure the pump doesn't come on when the micro is running, so I'll just shut that one down for a few minutes.

The thing you are seeing with your pump is the momentary starup draw which is around 4x+ of the running draw. [This draw may approach or even slightly exceed your gen rating.] Once that pump is running youre ok for virtually every load you have, incl micro not stove Where you are likely to have trouble is if there is much other load when the pump tries to start. Experiment til you find out what running combination of other items prevent the pump start [other motors running will be particularly critical]. ... Then avoid pumpstart when those loads are running.
larry

 

[Clint S]

You can even run one small burner on the cook top if you are careful with the load. The small burners are 12 to 1500 watts, not much more than running a coffee maker or the micro.

 

[Carl_NH]

I had a 5700 w runnnig unit with a 1.5 HP well pump drawing 20-22 amps starting 11 amps running and yes the genney dogged down. Also its big $$ if well pump fails so we would shut down heavy load circuits and take showers and run water pump selectively. We have 28 gal storage (two bladder tanks in series) so can go for a while with water between cycles.

I got a new (portable) genney 7 run/9K max last fall to run everything at once, but still dont run the microwave since the Mwave along with the fridge, and coffee maker draw large amounts of current - so we turn off the coffee maker and selectively use the microwave, but use the gas oven instead (or gas grill) to heat/cook food.

Carl