Generator: Microwave vs. Electric Range vs. Toaster Oven

[thinkxingu]

Hello All,
Wind storm blew out power the other night, so I had a chance to use my genny for the first time. 5,500 Briggs & Stratton: Able to run water heater, fridge, lights, and one burner on electric stove. Anything more threw a genny breaker (which makes sense) and did not like microwave!

Question: looks like one burner on my stove is around 1,400 watts and my toaster oven is about 1,200. I didn't try the toaster oven, but it seems like I should be able to use that in place of my range's oven, yes? Feedback on microwave use with genny?

Thanks!

S

 

[Adios Pantalones]

Is the water heater electric, or just the pumps are electric? Seems like a bit of a light load if the heater is gas/oil etc. I assume it's main 240/250V supply is plugged in through a transfer switch, or are you running multiple cords?

Limit the lights, unplug the fridge when using something with more juice and you should do better for the time you're cooking I think. My 5K genny runs fish tank, insert blower, old fridge, oil based water heater, few lights, WATER PUMP (the major draw, on startup), and a few other things just fine.

edit: what's good about a transfer switch is that you can selective throw the breakers for all but one or 2 circuits if you need juice somewhere in particular (oven). I'm not running my welder when the power is down or anything, but it's nice to have the giddy-up if I need power for something in particular.

 

[thinkxingu]

Hey There,
It's an electric water heater. I'm running the genny directly to my panel with a 30amp breaker (interlock protected). All our lights are CFL and I shut off all electric heat.

S

 

[velvetfoot]

You should measure your wattage with something like one of those kill-a-watt things, for 25 bucks.
That still doesn't do in-rush current, but I don't think that's much of a factor with a microwave, but maybe some.
You have enough juice to run the microwave with nothing else connected, for sure, but if it doesn't work, maybe it's an electronics/generator power quality problem.
Plus, some of those other things might have started at the same time, causing the overload.
Plus, as far as my limited knowledge allows, each leg of your 240volt feed can only be half the total, so if it's not balanced, you could have a problem there.
I think I would throw the water heater breaker and use that with discretion.

 

[Highbeam]

Yep, your problem is the 220 vs. 110 issue. Your water heater, and range evenly load both phases so the 2750 available on each leg has no problem handling those loads. Flipping on the microwave is about a 2000 watt load on only ONE phase. It would be great to have a 220 microwave that would only put 1000 on each phase but I've never seen one.

Everything will be happier with 220 volt loads so use the range. Also, the voltage regulator is often using only one leg to regulate the voltage for both phases so when you unevenly load the genset such as with a 2000 watt 110 volt load, you can really send the voltage both phases into strange places. For instance you'll get 100 and 140 instead of 120 and 120.

I've gone so far as to be sure that each of my freezers are on seperate phases so that the genset is evenly loaded.

 

[thinkxingu]

Highbeam, I know what you mean--when one of the breakers tripped on the genny, nothing would run if I shut the water heater breaker off! So, if I'm understanding correctly, every 220 item (Water heater/range) uses both phases whereas 110 uses only one. If that's the case, should I try to get my fridge and toaster oven on separate phases or do they not draw enough to worry?

S

 

[seige101]

Highbeam, I know what you mean--when one of the breakers tripped on the genny, nothing would run if I shut the water heater breaker off! So, if I'm understanding correctly, every 220 item (Water heater/range) uses both phases whereas 110 uses only one. If that's the case, should I try to get my fridge and toaster oven on separate phases or do they not draw enough to worry?

S

Sounds like only one leg of the 240 tripped on the generator, thats why nothing would run without the hot heater breaker on. It passes some power to the previously other dead leg. This causes wild imbalances within the system and will burn out devices quickly.

 

[Later]

The electric water hearers that I am familiar with are usually either 4500 or 5200 watts. Most counter-top kitchen appliances don't exceed about 1700 watts. Refrigerators have a high demand at start up and during defrost but aren't too demanding otherwise. Check the manufacturer's website for data on your model. Easier than crawling on the floor. 5,500 watts isn't a lot but it should be able to get you by.

 

[Highbeam]

Highbeam, I know what you mean--when one of the breakers tripped on the genny, nothing would run if I shut the water heater breaker off! So, if I'm understanding correctly, every 220 item (Water heater/range) uses both phases whereas 110 uses only one. If that's the case, should I try to get my fridge and toaster oven on separate phases or do they not draw enough to worry?

S

You are right that the 220 volt appliances use both phases. Since the two legs are out of phase and peak at 110 in opposite directions, the difference is 220. 220 is nice on a genset kinda like carrying one 5 gallon bucket of water in each hand vs. trying to carry both buckets in one. A balanced load.

Unless you are very familiar with your panel's circuit layout whip out your voltmeter and run the house on genset power. Plug in a big 110 device like a space heater. Trying to load one phase. Now go around and check voltage at the different outlets around the house and you will find that all of the circuits are running at one of two voltages. It might be 110 for one and 130 for the other phase. Now you have your home's phase layout and you can make efforts to load each phase somewhat equally. I have two fridges, one on each phase. If you have one fridge and want to use a microwave then I would be sure that those two are on different phases. Then use the kitchen plugs that are on the microwave phase when the microwave is off. That reserves the other phase for the high startup hit from the fridge.

Assume your fridge (at startup) and toaster consume about the same, 1500-2000 watts. Yes, that is significant, a big bucket, for the 5500 watt genset.

It is not terribly difficult to move circuits from one phase to another inside your panel. Even when under grid power you will benefit from the balanced load. The transformer that feeds your home will be happier.

 

[thinkxingu]

Believe it or not, the fridge is on the same circuit as the microwave. And toaster oven. Yes, I'll be changing that this summer when I begin the wiring for central air--I'll need to run a conduit to the attic for the handler, so I'll throw a couple more lines while I'm at it. I've a split with a finished basement, so getting into the walls from the attic is the only way. In any case, when I do that, I'll run dedicated lines for the fridge (mic and toaster oven will still be on same circuit) and audio system.

S

 

[Highbeam]

Today's codes require that microwave to be on its own 20 amp circuit. I even had to have one of those single outlet plug ins. The micro should be on a different circuit than the fridge AND a different phase if possible. I'm jealous of you putting in a central heat pump system, that's one of my goals someday since we have wood or non-ducted electric resistance heat.