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1) The entire house looses power including all receptacles, lights, everything?
2) Have you tried to temporarily relocate the microwave oven and plug into another circuit such as a bathroom or another kitchen counter top receptacle using a heavy duty extension cord (12 AWG wire on the extension cord) and see if the microwave will work or not?
3) Does the main breaker in the electrical panel trip or does the circuit breaker for the microwave oven trip?
4) When this occurs, do any of your interior lights dim or flicker at all prior to loosing power throughout the entire house?
5) Do you have any adjacent neighbors that may be experiencing similar problems and/or dimming or flickering of lights?
1) Is your main panel a 100 amp service or a 200 amp service? Do you have a sub-panel installed in the house or just the main electrical panel?
2) Is the AC located on the same circuit breaker as the microwave oven or located on separate breakers?
3) I assume that if you don't use the AC or the microwave, everything is normal and nothing trips?
4) Was there any recent electrical work performed in the house?
5) How old is the house? What is your wiring scheme? Metal conduit, Romex, Knob & Tube?
6) Are either the AC or the Microwave oven on a GFCI or AFCI protected circuit? Ground Fault or Arc Fault?
7) Same thing occurs if you use an extension cord and plug the window AC into a different circuit?
8) Does the branch circuit trip along with the main breaker or is it one or the other that trips?
Can you provide me with the circuit numbers of the microwave oven and the window AC located on the directory panel of the main electrical panel? The left side of the panel will be odd numbered and the right side will even numbered. Are the microwave and AC circuit breaker located on separate full size breakers or are they located on tandem (mini) breakers?
9) Do you have or can you borrow a 2-prong AC voltage tester or a voltmeter that is capable of measuring 120 and 240 volts AC? If so, are you comfortable to verify a few quick voltage measurements inside your main electrical panel?
1) OK, very good... thanks for the replies.
2) Let's try this.........turn the breakers for both the window AC and the microwave oven to OFF. Temporarily plug the microwave into a different receptacle and let me know what happens.
3) Turn the breakers back to ON and plug the microwave back into the original receptacle. Let the microwave run and watch very carefully if any of your lights dim or flicker. Turn on as many lights in the kitchen or nearby room so you can observe.
4) I need to know if these two appliances are sharing 1 circuit or if they are on separate circuits? Is the window AC unit 120 or 240 volts?
1) I suspect a few things that are possible. I asked the question about the dimming of lights and that usually indicates a loose neutral wire connection either at the electrical utility transformer or inside your meter socket or inside your main panel. Appears that you don't have that problem since you do not notice any dimming or flickering of lights.
If the main is tripping, that tells me that the entire panel is being overloaded or that the main breaker is faulty. Main breakers can become faulty, but this is not a common problem. If you only have 5 circuit breakers, that is a very small electrical panel and circuits are not broken out accordingly, thus causing an over-load condition.
The Window AC unit should be on it's own dedicated circuit. Same thing for the microwave oven. Both of these types of appliances generate a fair amount of wattage and depending if they are located on the same circuit, the circuit becomes overloaded and breakers start to trip. Both of the appliances need to be on their own dedicated 20 amp circuit and not shared with any other connected or plug-in loads.
2) Not sure how many spaces your main panel has or the square footage of the home or the service amperage, but sounds to me that the main electrical panel is way undersized if you only have (5) five branch circuit breakers?
1) Do you have a 100 amp service now?
Is your service from the electrical utility over-head or underground?
2) What is the approximate square footage of the house only including habitable areas? Do not include a basement, attic, crawl space or garage.
3) Does the house have a Central Air Conditioner, Electric Heat, Baseboard Electric Heat, Electric Dryer, Electric Range or Double Oven or Electric Water Heater, Sump Pump, Well, Ejector Pump?
1) OK, the house is somewhat small, if you have a circuit breaker panel and not a fuse box, I would assume that it is a 100 amp service since the house was built in the late 60's or early 70's. Doubt that you have a 60 amp fuse box service just due to the time frame the home was built.
2) A 100 amp service should be sufficient for that square footage of a home. However, if the panel only has 5 branch circuit breakers plus the main, the panel is way undersized, even back then it was undersized, not too mention all of the additional electrical items that modern day homes now have. A 100 amp panel should have a minimum of 24 available circuits. Yours only has (5) five).
3) I would recommend to have a licensed electrical contractor assess your existing electrical panel as well as a breakout of circuits in the home. If you only have 5 circuits, the wiring needs to be split up accordingly so not to cause potential over-loads. If the house is built with metal conduit, this is doable. If the house was wired with Romex cable or BX, then it will be costly to require portions of the home and split the wiring. I would not be able to provide you with a budgetary price for breaking out the circuits and having the correct amount of circuit breakers in the panel. This will run into the low thousands if that is required.
4) If the panel is 100 amp, but too small and insufficient amount of breaker spaces, then a 24 or 30 space panel will be required and you're looking on average of $1000 just for the panel swap out, plus the wiring breakouts in order to correct any overloading problems.
1) You're welcome... .glad I could assist. Thank you for the excellent rating....much appreciated!
Take care and have a great evening...............Thanks..............Kevin!