Question about Microwave Ovens

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My Kitchen counter receptacles are wired to a 4 pole quad circuit breaker with twin 2P 15 amp but 1 of the poles trips as soon as it is turned on. I replaced the breaker and the same thing happens with a new breaker. The house is 15 years old and this just started happening out of the blue. What could be the cause and how do you fix it?

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When you close the microwave oven door, the latches operate some switches. One of them, the interlock monitor, is probably stuck closed or is out of adjustment far enough not to operate. When this happens, the circuit breaker will trip (or the fuse in the oven will blow) when you start the cook cycle. If the oven door gets slammed, this can damage the switch.

Another possibility is that the high-voltage (HV) rectifier diode is shorted. This mat be a separate part or it may be built into another piece called the HV capacitor.

The first step is determining the cause. An ohmmeter can be used to check the switch for proper operation and to see if the diode is shorted. The switch should change from very low resistance (nearly a short-circuit) with the door open to very high (open-circuit) when it's closed. If it doesn't behave like this, make sure the door latch is operating it correctly. If it is, the switch is bad. The diode should measure a very high resistance (close to infinite) with the test leads connected one way, and drop to a low value when the leads are reversed. A low reading in both directions means the diode is shorted. Then it's a matter of obtaining and installing new parts as needed.

MICROWAVE OVENS USE HAZARDOUS VOLTAGES WHICH CAN KILL YOU. Make sure the oven has been unplugged for some time before removing the cover. Then discharge the HV capacitor by momentarily touching its terminals to the microwave oven chassis using an insulated jumper lead. Some troubleshooting experience is helpful. If you aren't comfortable with your ability, be safe and let a professional repair the oven, or give an estimate for the cost of the repair. For a small countertop model, it may be more economical just to buy a new one.

If you decide to try repairing the oven yourself, be careful. Replacement parts are available from many online sources, and possibly locally if you have an appliance parts store or service shop in your area. Good luck, and thanks for using Fixya!

Posted on May 28, 2011


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Posted on Jan 02, 2017


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1 Answer

Trip Circuit Breaker

The circuit breakers may both be functioning properly. What might be happening is that both circuits have other current drawing appliances on them. The circuit breakers react to the sum of all of the currents drawn by all of the devices on that circuit. So, if you have a 15 amp microwave and an 8 amp refrigerator on the same circuit, you would overload a 20 amp circuit by 3 amps.

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Blowing breaker

In general house hold circuit breaker of the house is 15 Amps or 20 Amps.

Either you have defected (weak) circuit breaker and wiring or bad Microwave oven.

The 99.99 % house hold Microwave ovens pull less than 15 Amps. They may have internal ceramic 15A fuse or 15 Amp internal circuit breaker.

To isolate your problem:

1. Plug your Microwave oven to different areas (different electrical circuit) if the different circuit breaker still trips... your Microwave oven has a short - Most of them has a small ceramic fuse 15 amps fuse.-also check some inter lock switches at door .

2. If the Microwave oven works Ok then you may have:

2a. You may overload the existing electrical circuit, try to unplug some other appliances

2b. You may have bad electrical outlet receptacle (Replace it with the same type , - may need helps from licensed electrician)

2c. Weak or defect house hold circuit breaker. (Replace it with the same type , brand - may need helps from licensed electrician)

Jan 24, 2014 | Goldstar Microwave Ovens

1 Answer

On breaker 7 that runs the lights and receptacles in 2 bedrooms, the light in my crawlspace, the light in the attic, two ceiling lights in the kitchen (but no receptacles), and the outlet for the...

1) You must see if the circuit where the microwave is overload, you must use the amperimeter and see how many amperes are reading when all the load in the circuit 7 are running. if is normal about 10amp-12amps the circuit is o.k
2) test the c.breaker can be faulty, since there are NOT tripped.
3) However you must see if the lines for power in that circuit is loose?
4) Tight very well the Neutral +Ground
5) see the diagram attached, and correct if the outlet is wrong.
6) If you are NOT qualified to do this electrical job , call some electrician for to avoid danger to your home or yourself.

God bless you198ace60-27b8-4867-bf57-4b0086ba4f59.jpg5755a5d4-1228-483b-969d-82f0a795cbc3.gif
Of course you must test the microwave magnetron for faulty or short in the magnetron+diode+transformer+capacitor. ISOLATED the microwave first and then troubleshooting the circuit of your home.
God bless you

Nov 01, 2013 | Whirlpool Microwave Ovens

1 Answer

I was cooking food for 1 minute and it just shut off after approx. 30 sec. There are no lights or power now. The outlet is fine. The unit is 4 yrs old.

Check your other appliance. You may have tripped a break. If they are all functioning, and you have no dead outlets in your kitchen, then the unit will need to be serviced. Hope it's the breaker.
a 1200w microware will draw 10 amps all by itself. Your outlets are most likely on 15 amp breakers, so it wouldn't take much amp draw from another kitchen appliance to trip the breaker.

May 11, 2011 | Dacor DMT2420SS Microwave Oven

1 Answer

Need hook up diargam for 240 volt 30 amp washer dryer residential xyo-gnd for free .like your web site said. or i will presume this is just a scam trying to lure people in for some...

Hi Watsonelecco!

No scams here... most of us on FixYa are like me.... we enjoy helping people out with their everyday problems. I work nights and do this as a hobby... I used to teach advanced electronics and Radar for the US Navy.
It is difficult for me to give you a diagram for "xyo-gnd" since the term is not familiar to me, even though I worked as an industrial field service engineer. My guess is that you need to connect your washer/dryer to your electrical outlet.
First thing.... I need to know where you are located, and what type of power service you have coming into your home. Most US homes are wired for 115 Volts and require a separate input for 230 volt appliances. Most European, Australian, and Asian homes are wired for 230 volts and connecting your washer/dryer will be simpler, but still require some work.
The first thing we will need to know is how the power comes into your home and how it is distributed. Look at your circuit breaker panel. You will have a mains coming in that feeds a 2 pole "main" breaker- it will be rated at between 100 and 300 AMPS in most homes.
Next... the other breakers in the panel.... how many are "2 pole" breakers (what looks like 2 switches connected together) and how many are single pole? Only a 2 pole breaker can supply power for your washer/dryer.
Now, you need to determine which of the two pole breakers are rated high enough for 30 amp service. If none say 30 amps or higher, you will need to install a new breaker and run a 10/3 AWG type UF cable to where you are installing the washer/dryer. Find a recepticle that matches your washer/dryer plugs, and install it with the black wire to the brass lug, the white wire to the silver one, and the green wire to the green lug.
Once you have the wiring done, you will be good to go!
If you already have a dual breaker rated at 30 amps supplying an outlet where you are installing the washer/dryer, match up the plugs/outlets the same way... black wire to brass, white to silver, green to ground. You may have to purchase either the correct outlet, or (more likely) the correct plug, since most units do not ship with power cords.

Apr 07, 2011 | Microwave Ovens

1 Answer

15A breaker tripping; Is this the right size breaker for the unit?

The breaker is sized according to the size of the wire used in the circuit. The breakers task is to protect the wire from an over current.
The allowed sizes are
#14 wire .... 15 amp breaker
#12 wire ..... 20 amp breaker
#10 wire .. 30 amp breaker
To check if the oven and circuit are compatable .. run an extension for the oven to an outlet outside the kitchen and see if it holds.

Please Vote !!

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2 Answers

Microwave / Frigidare PLMV

Chek the high voltage capacitor and the diode . If one of them are short there is a chance for tripping the breaker

May 25, 2009 | Frigidaire PLMV168 Microwave Oven

4 Answers


Two possible causes.

First (and most likely) the circuit is being overloaded. This kitchen circuit may be shared with another appliance (like the refrigerator) which is drawing enough power when both are running to trip the breaker. A Typical kitchen circuit is 20 amp with #12 wiring. So an 1800 watt microwave might draw 13 or 14 amps while a fridge compressor kicking in can surpass 7 amps before it levels off. If this is an older home the kitchen may have a 15 amp circuit with #14 wiring. If the circuit is a 20 amp you will have to split the appliances onto separate circuits. (Under code a kitchen must have a minimum of 2 separate appliance circuits). If it is a 15 amp you might be able to split them as well or may be looking up upgrading the breaker and the wiring from 15amp #14 to 20 amp #12 (but you could still have the same problem).

The other possibility is a short or loose connection. If splitting appliances onto their own circuits doesn't fix this you would probably want an electrician to come in and check for other underlying causes which could represent a fire hazard.

Hope this helps.

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1 Answer

Our Engineering Compamy Here In CANADA Montreal Quebec, Is Recommending To Use A 20Amp 2P-120V GFCI Breaker To Split A 15/20---120V Receptacle?? I Heard From Siemens Canada, That We Can Connect The Split...

First of all, is this to power a microwave?

If so, it is always recommended that microwave be on it's own breaker with nothing else attached to that breaker. This is due to the typically high current draw (12+ amps) of the oven.

The most important items which should be on a ground fault interrupter are those which may fall into water or get wet, but it's of course never a bad idea to use a GFI.

If this doesn't answer your question, please rephrase it with some more details.

We're happy to help and we appreciate your thoughtful rating of our answer.

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Make sure it is plugged into a 20 amp circuit. If it is in a kitchen it should be a 20amp breaker if it trips a 20 amp breaker it needs to be replaced. If it is a new house and you plug it in in the kitchen and it trips a 15 amp breaker then the house does not meet code. ref Article 210.52(B)(1) NEC

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