One circuit often blows

Lately, one circuit on my box blows. It covers the microwave and regular oven. I could understand it blowing when another heat-using appliance, like toaster oven or toaster runs at same time as microwave. But now it's blowing all on its own.

Last time, today, only the micro was being used, to "reduce" a glass dish of chicken drippings.

Can one circuit go bad all on its own? If so, why? And what should I do about it.

Any info appreciated.

Reply to
Higgs Boson
Loading thread data ...

Maybe the breaker is loose or going bad.

Reply to
LouB

20 amp breaker for my living room was tripping so I swapped the wires to my bedroom. Problem stayed with the breaker indicating the breaker was bad.

Jimmie

Reply to
JIMMIE

Breakers go bad. Buy new breaker.

Jon

Reply to
Jon Danniken

As others have said, probably a bad breaker.

Quick test: Plug the microwave into another circuit and use it as normal.

Reply to
DerbyDad03

What is the "regular oven" you speak of? Like a toaster oven but larger? It may have been marginal all along. What is the rating of the two appliances? If the microwave motor is starting to go, it may be pulling more amps that it normally does.

Also. what is the actual voltage coming in? In the summer with heavy loads, the power company sometimes reduces the voltage a bit and that increases the amps. If you live in an area of high tempertures that may be going on some days as the AC load goes way up.

120 volts with a 1500 watt appliance = 12.5A reduce to 110 volts and you get 13.6A Maximum safe load on a 20A breaker is 16A

Others are saying a bad breaker, but while it may be that, I'm guessing overload. Personally, I'd not run a MW and oven together for just that reason.

Reply to
Ed Pawlowski

The best test is to clamp an ammeter on the circuit and see what it's drawing. If there is nothing on the circuit but the microwave being used, it's probably a bad microwave or breaker

Reply to
RBM

Try plugging it somewhere else. If the same problem then it's the device, if not it's the breaker.

Reply to
LSMFT

Have a new dedicated 20 amp circuit installed to the microwave.

Older homes have many things on the same circuits. You can resolve breaker tripping problems by placing "power hogs" on their own breakers/circuits. Then you just need to run one new wire to one thing.

Reply to
Bill

Since nobody has mentioned this yet and it sounds like it's a kitchen circuit, is the breaker perchance a GFI one?

The microwave may have marginal "hot to ground" leakage which sometimes becomes high enough to trip a GFI breaker.

If it's not a GFI breaker, then I'll side with those who say, "change the breaker.

Jeff

Reply to
jeff_wisnia

Whaaaaat?

I seriously doubt that you are correct about that. I say the current at

110 volts would be closer to 11.5 amps. It's quite unlikely that an appliance would be sophisticated enough to continue to consume the same number of watts when the voltage is lowered.

Jeff

Reply to
jeff_wisnia

I didn't make the laws of physics, but I usually follow them. Amps = volts ÷ watts. If one changes, another will. Are you saying the rated watts of the heating element will change?

Reply to
Ed Pawlowski

Except the load usually behaves the other way. !500 watts at 120 volts, and 1250 watts at 110.

The OP wasn't running them together - they were on the same circuit, but he was ONLY running the Microwave - and the circuit breaker is by far the most likely problem.

Reply to
clare

No, what he (and I) am saying is the resistance (effective load) will stay the same, and if the voltage drops, the power consumed will also drop. The only place that doesn't happen is with induction motors where the back EMF drops, making them draw more current when the voltage drops.

Reply to
clare

The rated watts of a heating element is generally an estimation based on the typical outlet voltage divided by the resistance of the element. If the voltage goes down the resistance doesn't change (much) and so the wattage and amperage go down.

However...a microwave doesn't use a heating element as such. It does have a high voltage power supply which IS pretty sophisticated (controlled by solid state electronics) it may try to maintain a constant output power which would require a higher input amperage at a reduced input voltage. Or, it may only care about maintaining the correct frequency and let the power fluctuate with input voltage... I'm not sure which...

Reply to
Larry Fishel

And most electronics (anything with regulated power supplies).

Reply to
krw

The high voltage supply of a microwave oven is as simple as it gets. Just a transformer, diode and capacitor. Then the one tube magnetron. If the voltage drops, the heating power of the microwave goes down. It does not even care about the frequency all that much. Just a simple oscillator circuit.

The microwave ovens with the mechanical timers are about as simple as they come.

The only complicated electronics in the microwave is the ones with the electronic keypads for setting the clock and time. They are not really that much more than an alarm clock.

Reply to
Ralph Mowery

+1 Agreed. It's interesting how the guessers and faux experts climb out of the woodwork for electrical questions as though it were the safest, easiest thing in the world to understand and work with. The degeneration of this thread has gone far enough off base as to make choosing which responses are useful and which are not.

Twayne`

Reply to
Twayne

how does it "cover the microwave and regular oven"? And yes, you could have a weak breaker. Replacing it is the first step to solving the problem. (especially if this hasn't always happened).

Reply to
Steve Barker

Our panasonic looses output power when the voltage sags. An INVERTER type (newer high end) system may maintain the output, as does a regulated switch-mode type computer power supply .

Reply to
clare

HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.