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Aging microwave oven

  1. Nov 23, 2014 #1

    DaveC426913

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    Can an aging microwave oven reaching the end of it life result in a change in its power draw?

    I've had this microwave for many years, and I know they do wear out, but it has begun blowing a breaker when used. I can't think of any changes to our electrical draw in the house that might affect it. So I'm looking to see the unit itself could be changing.
     
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  3. Nov 23, 2014 #2

    Doug Huffman

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    Compare the time to heat a known mass of water from STP to a rolling boil with its rated heating power. Any power beyond that must present as excess heat load. More likely the CB is older, aging and should be at least re-seated if not replaced. It is a thermal sensing device and contact resistance RI^2 loss adds to sensed heat.
     
  4. Nov 23, 2014 #3

    DaveC426913

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    It certainly does seem to be not heating properly.

    But why would that trip a breaker? And not a overheat breaker in the oven, but a breaker in my panel.
     
  5. Nov 23, 2014 #4

    russ_watters

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    A loose or corroded connection can cause something to get hot that isn't supposed to, reducing the output while increasing the input. If you have another circuit you can plug into for a test, try that because the "loose or correded connection" could be in the breaker. But otherwise, sounds like you need a new microwave.
     
  6. Nov 23, 2014 #5

    DaveC426913

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    OK. Perfect. I wanted to ensure it was plausible before simply going out and purchasing a new one.

    Elec. panel is only a couple of years old, having been uprgraded from fuses, (though the wiring has not been updated), so it's less likely to be the breaker.

    I won't bother with the 'other circuit' test since it would only be conclusive should the continue to blow. If it does not, then it proves little.
     
  7. Nov 23, 2014 #6

    russ_watters

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    I wouldn't conclude that -- a newly installed, bad circuit breaker might take a couple of years to die. But if you are going to get a new microwave anyway, that is kinda moot.
     
  8. Nov 23, 2014 #7

    DaveC426913

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    Well, I wouldn't say it's moot...

    If I buy a microwave but the problem is the breaker, I'll have bought a new mc for nothing, and it'll still trip the breaker.

    It's a risk, but I'm going to bet the odds on it. mc's do get old and faulty.
     
    Last edited: Nov 23, 2014
  9. Nov 23, 2014 #8

    nsaspook

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    Something to have for this and general house electrical testing.
    https://www.amazon.com/P3-P4400-Electricity-Usage-Monitor/dp/B00009MDBU
     
    Last edited by a moderator: May 7, 2017
  10. Nov 23, 2014 #9

    russ_watters

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    Moot insofar as buying a new microwave will answer the question about the health of the breaker. Like you say though, odds are better that it is the microwave.
     
  11. Nov 23, 2014 #10

    Doug Huffman

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    If your microwave heater "does not seem to be heating properly" and is drawing excess current then that current represents power that MUST be appearing somewhere as heat.

    A microwave heater is tuned to resonate water. One might say that it loses efficiency by losing tuning, but that would result in lower load and lower current and not increased current. The device doesn't try harder to heat.

    If your CB is tripping then it is tripping on over current and you need to find that RI^2 heat or it is tripping on overheat that can only be local in the contacts.
     
  12. Nov 23, 2014 #11

    DaveC426913

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    Yes but I'm less concerned about the heating than I am about why it is tripping the breaker. The 'poor warming' as far as I am concerned is simply a secondary symptom, to point me in the direction of what might be wrong.
     
  13. Nov 23, 2014 #12

    DaveC426913

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    New microwave purchased.

    Will return with results.
     
  14. Nov 23, 2014 #13

    Doug Huffman

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    Without even trying the appliance on a different circuit? Truly a consumerist culture.
     
  15. Nov 23, 2014 #14

    DaveC426913

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    Yup. It is a conscious choice. I have reached that point in my life.

    And it's a trickle down. I am financing the 2nd-hand gadget repairers in my neighborhood. It will only be on the curb for an hour or two.
     
  16. Nov 23, 2014 #15

    Mark44

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    You didn't say how old the wiring is. Hopefully it's not knob and tube.
     
  17. Nov 24, 2014 #16

    Borg

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    I have a microwave that was throwing a system error starting several months ago. I found a video that showed how fix it by removing connectors from the control panel and cleaning them with rubbing alcohol. Unfortunately I'm having to take it apart and clean it about once per month. I think that my micowave is an alcoholic.
     
  18. Nov 24, 2014 #17

    Doug Huffman

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    Anytime I have to get into an appliance, breaking and re-making connectors, I use a contact improving oxidation inhibiting paste. Most recently on a heated mattress pad that was baking the cheap plastic insulation at the 0.050 connector.
     
  19. Nov 24, 2014 #18

    DaveC426913

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    aaaaaaaaaaaaand the old one has been spirited away...
     
  20. Nov 24, 2014 #19

    Borg

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    That's a mouthful.
     
  21. Nov 24, 2014 #20

    Mark44

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    You're not supposed to eat it. ?:)
     
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