power issue at house effecting only microwave


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Old 12-12-05, 11:40 AM
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power issue at house effecting only microwave

I have a house that when I plug in a microwave into any outlet the microwave acts all strange. What happens is if you watch the electronic time clock you can see it "flip" off and on every few seconds. sometimes its on for 10 secs and then on off on off every second for a few. Its almost like the unit looses power for a split second and then comes back on. I took this same microwave to another house and it works perfectly there. What could be wrong with my house's power? My house was built in 1980 and it does not have a ground outside. I'm assuming it must be grounded to the power companies line.
 
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Old 12-12-05, 11:45 AM
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Does this problem with your microwave happen anywhere in your house, or only in the kitchen?

The neutral that the power company provides is grounded either at the meter box or at the main panel. You service is most likely grounded to the water pipes that enter your house.
 

Last edited by John Nelson; 12-12-05 at 08:18 PM. Reason: off topic
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Old 12-12-05, 11:50 AM
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You need to check the voltage you are actually getting. It could be too hoigh or too low.
 
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Old 12-12-05, 11:50 AM
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I have tried the microwave on 5 different outlets in different rooms of the house and the same problem occurs all all outlets. Infact the microwave outlet is a dedicated 20 amp circuit from the breaker panel. I'm not sure what would cause this issue with only the microwave as when I plug in other devices (refrig, oven's) etc into the house wiring there is no issue of this matter.

A coworker thinks my house is not grounded well and that this microwave has some sort of a very sensitive internal GFI and that trips everytime the house looses ground.

I dont know if I should go to the expensive to have a electrican come out and add a grounding rod system at the breaker box if this wont help. Also is this type of repair expensive? I'm not sure how much to expect this type of repair from an electrican.
 
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Old 12-12-05, 12:02 PM
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I highly doubt you suspected lack of ground is the problem. You can buy a tester for about $8 at a home center that plugs into a receptacle. It has three lights on it that indicate various conditions like hot & neutral reversed, lack of ground, lack of neutral etc.
 
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Old 12-12-05, 12:13 PM
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I'd call your power company and ask them to come out and check your power. Most power companies will do this promptly and without charge. You could have a loose neutral that is making the voltage too high or too low (as Joe suspected).
 
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Old 12-12-05, 04:38 PM
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I pulled off my electical panel cover and here is what I see. There are 3 large alumin wires coming from outside. 2 go to the 2 main breakers, and the 3rd one goes to a bar on the side of the panel. That bar on the side has both the white house wires and the copper ground wires attached to it. There is no additional ground wire to be found on that side bar (IE: no copper going to a water pipe and there is no rod in the earth outside either). Is this a problem?
 
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Old 12-12-05, 04:44 PM
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Originally Posted by WFO
dallastx75206....
Turn the lights on in your house so that they are representative of both legs of your service. Turn on the microwave and see if some lights get bright while the others dim.
If the lights only dim, you probably have a loose connection. If any get brighter (and these will be on the opposite leg of the one feeding the microwave) you have a neutral problem.
I turned on lights throughout the house and then had the microwave starting and stopping. I could see no lights diming or any lights getting brighter.
 
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Old 12-12-05, 05:13 PM
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You are fixating on the no ground rod question. I don't believe the lack of a ground rod will cause this problem. There could be a ground rod attached somewhere else like at the meter.
 
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Old 12-12-05, 06:57 PM
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Not a ground problem, a neutral problem. And judging from his response on the "brighter, dimmer" question, I'd say that's not the problem.

Get a voltmeter and put the probes in the un-used half of the outlet you have the microwave plugged into and see exactly what the voltage does when you turn it on. If you don't see anything, it may be the microwave. (I know you tried it at another house, but sometimes loose connections have a nasty habit of temporarily making ....especially after they've been bounced around.)
 
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Old 12-12-05, 06:57 PM
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Originally Posted by John Nelson
I'd call your power company and ask them to come out and check your power. Most power companies will do this promptly and without charge. You could have a loose neutral that is making the voltage too high or too low (as Joe suspected).
With de-regulation in Texas, the company you buy your energy from is not the same company as the company that delivers the energy. If you call the "wires" company (in this case TXU Electric Delivery), I'm sure they will advise that there will be a charge if the problem turns out not to be theirs.

Joed is right about the possible lack of a ground rod being unrelated to your problem. And WFO gave you good advice on how to check for a loose neutral or loose connection (not sure why it was deleted - I guess it offended one of the moderators here). Anyway, since the procedure WFO suggested did not shed any more light on the problem (pardon the pun), I believe an electrician would be a better choice. An electrician could check the current drawn at the microwave and also monitor the voltage. TXU will only check the voltage at the meter and the connections on the service and secondary. If the connections inside the meter socket are loose (and most likely, they are - even though it may or may not be your problem) TXU will most likely charge you for the service call.
 
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Old 12-15-05, 05:11 AM
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Originally Posted by WFO
Get a voltmeter and put the probes in the un-used half of the outlet you have the microwave plugged into and see exactly what the voltage does when you turn it on. If you don't see anything, it may be the microwave. (I know you tried it at another house, but sometimes loose connections have a nasty habit of temporarily making ....especially after they've been bounced around.)
Ok I checked with a voltmeter. When the appliance is off the outlet reads between 124V and 123V. It changes every few seconds. Then when i power on the microwave the same outlet reads between 120V to 119V. Changing every few seconds. Does this information shed any light?
 
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Old 12-15-05, 05:32 AM
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Actually, that sounds pretty normal.

In your original post you stated that "the electronic time clock you can see it "flip" off and on every few seconds. sometimes its on for 10 secs and then on off on off every second for a few. Its almost like the unit looses power for a split second and then comes back on."

Is it only the display that seems erratic? Most microwaves have a turntable. Does it stop and start? Does the unit hum and then go quiet at the same time the display is going on and off?

Dallas75208
 
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Old 12-15-05, 05:37 AM
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yes if your using the microwave the whole microwave stops (including turntable) and then restarts a split sec later. then the microwave can work for 10 secs without issue and then it happens again and then maybe 3 seconds pass and it happens again, then maybe a minute passes and it happens again. no real pattern to this. If your not using the microwave you can see the clock display loose power in this same pattern. Also if you have the door open to the microwave when the blip happens the interior light will go off as well as the clock display flash.
 
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Old 12-15-05, 05:53 AM
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I know you said that you took the microwave to another house and it worked fine but it really does sound like there is something wrong with the microwave. Especially since the display malfunctions with it just sitting there plugged in. A microwave is about 1000 watt max. Does a hair dryer (1500-1800 watts) behave as erratically?
 
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Old 12-15-05, 05:59 PM
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Might not be this, but thought I'd mention it. We've been having lots of weird outlet problems in the house we moved into. I bought a space heater, and it wouldn't work. The lights came on, but not all the way until I pushed down on the plug. I replaced all the outlets.

The cause was due to back stabbing. Every one of them. The wires might have been oversized or something but when you apply pressure to the outlet, the wires can move a little and mess up the connections and spin around. Especially strain on outlets, like vacuuming, pulling cords, or whatever, so maybe check to see if the wires are back stabbed, and if so, connect them properly with the screws.
 
 

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