Microwave causing voltage spikes?


Old 11-29-04, 08:24 PM
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Microwave causing voltage spikes?

This thread is a bit similiar to my very last thread I just wrote. I have had many DVR (Tivo's, hard drive video recorders) blow up. My cable company has given me the second place ribbon for the most amount of blown up DVR's from any one residence.

I did have a high voltage problem up until recently, until the electric company dropped it down from 128v to 125v (126 v is the legal limit). Now since then no blow ups.

But, the other night while heating up a cup of water in my microwave, my DVR/digital cable box had a major hickup. I thought it was blown up. It went offline and was what I thought completely shot. The next morning it apparently decided to reboot and all was fine. Not sure what was going on.

I stuck my volt meter in the socket to see what was happening. When the microwave was on the voltage went from 123 v, to 122 v, and up to 124 v, all in one minutes time. So obviouly the microwave was having an impact on the available voltage.

My question is, is the voltage drop and increase normal? Also, can this sway screw up sensitive harddrives?
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Old 11-30-04, 04:45 AM
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We need some more information.

When you say you 'stuck my volt meter in the socket' do you mean the socket that the DVR was plugged into, or do you mean the socket next to the microwave.

Do you know if these are on the same circuit? (When you trip the breaker for the microwave, does the DVR turn off?)

If you watch the voltage _at the DVR_ with the microwave off, what happens the instant the microwave is turned on?

Finally, disconnect your DVR from wall power and from the incoming cable. Now use your meter to check for voltage between your electrical ground and the grounded shell of your incoming TV cable.

Old 11-30-04, 01:16 PM
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WELL GOING FROM 122-124 IN 60 SECONDS IS NOT THAT BIG OF A PROBLEM. bnasic electric teaches u that when place a load on a supply system it is common and acceptable for the voltage to drop.
also are both these devices on the same circuit and what is the voltage at the mains in your panel
Old 11-30-04, 01:49 PM
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Fluctuations of a couple of volts is normal, and unavoidable. Wire has resistance.
Old 11-30-04, 08:43 PM
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Thanks for your replies. I will do further investigating and get back.

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