Microwave tripping breaker

Could be magnetron failure (shorted)

There must be a fairly major issue with your microwave to trip a 20 amp breaker. I would recommend taking it to your local repair shop or replacing it.

Generally microwaves should be on their own breaker. Hard wired ones are required to be by code.

If yours has a plug - make sure the plug is original with the unit, not added later or spliced onto hard-wired power leads.

Plug into and outlet rated 15A as the only thing on a 15A branch circuit and try again. If it still trips, try a 20A line and circuit. If it trips that, trash the microwave and buy a new one. Nothing is meant to be repaired inside.

Answered earlier, another tips is to disconnect the power to the board and see if the circuit breaker holds, if not check the main line circuit.

The magnetron probably has a partial short pulling more current than normal as it runs, the other two items that give trouble is the high voltage diode, "sometimes cracks" to the high voltage capacitor, "usually shorts"

If the breaker is an earth leakage type, it is possibly an earth leak problem which could be caused by insulation breakdown on the heater inside the microwave.
I would consult an aporved electrician for advice.

from online Microwave Repair Manual: Totally dead oven (no lights, no clock, no display, no fan, no heat...)First, check power to the outlet using a lamp or radio you know works. The fuse or circuit breaker at your service panel may have blown/tripped due to an overload or fault in the microwave oven or some other appliance. You may just have too many appliances plugged into this circuit - microwave ovens are high current appliances and should be on a dedicated circuit if possible. If you attempt to run a heating appliance like a toaster or fryer at the same time, you *will* blow the fuse or trip the circuit breaker. A refrigerator should never be plugged into the same circuit for this reason as well - you really don't want it to be without power because of your popcorn!

If you find the fuse blown or circuit breaker tripped, unplug everything from the circuit to which the microwave is connected (keep in mind that other outlets may be fed from the same circuit). Replace the fuse or reset the circuit breaker. If the same thing happens again, you have a problem with the outlet or other wiring on the same branch circuit. If plugging in the microwave causes the fuse to blow or circuit breaker to trip immediately, there is a short circuit in the power cord or elsewhere.

The microwave oven may be powered from a GFCI outlet or downstream of one and the GFCI may have tripped. (Removing a broken oven lamp has been known to happen.) The GFCI outlet may not be in an obvious location but first check the countertop outlets. The tripped GFCI could be in the garage or almost anywhere else! Pushing the RESET button may be all that's needed.

Next, try to set the clock. With some ovens the screen will be totally blank following a power outage - there may be nothing wrong with it. Furthermore, some ovens will not allow you perform any cooking related actions until the clock is set to a valid time.

Assuming these are not your problems, a fuse has probably blown although a dead controller is a possibility.

While you can do some repairs on your microwave, what you don't know can kill you... even on an unplugged microwave, so make sure you understand the dangers and how to reduce them before you try anything inside a microwave. If you want to do more yourself, go to the link at the top of this post.

I have a hard time believing that the home's main breaker is tripping instead of the branch circuit breaker that feeds the microwave. I suspect it is really just a difference in terms. You should disconnect it and try using in another outlet - preferably one on a different circuit if possible. If the breaker continues to trip; this appliance should be disconnected and either be discarded, repaired or replaced before using again.

If the microwave works as expected (on a different circuit), it may indicate the original circuit is overloaded. Microwave overs are supposed to be installed on a dedicated circuit. This means only one outlet is on the circuit - no other loads (lights, appliances, etc.) are permitted on this circuit. A microwave typically requires 10 Amps or more when on "high" and will require a significant portion of the power supplied by a 15 or 20 amp circuit breaker. There is little unused to power much of anything else. If other appliances go out when the microwave trips the circuit breaker, you should contact an electrician to have a dedicated outlet installed for the microwave.

I hope this helps!

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

check for a shorted hi voltage capacieor ,transistor or shorted multiplier diode