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Thread: Dimming lights

  1. #1
    Join Date
    Feb 2013
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    Texas
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    Default Dimming lights

    My home was built in the 50's and has the original wiring .
    Just 3-4 days ago all the ceiling lights would dim as the microwave was turned on .
    I turned off all lights except for one and that still dimmed on microwave use . I have metal incased wiring under the house and wiring in the attic also . I believe the ceiling lights are separate from the wall plugs . The washer also causes this . I believe that the washer is on a dedicated circuit as it
    appears to have been run directly underground to the outside box .
    no breaker has tripped outside and no fuse has blown inside .
    Whats going on here ?

  2. #2
    Join Date
    Dec 2010
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    Houston Texas
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    2,363

    Default Re: Dimming lights

    It sounds like you don't have enough amps coming into the house. What does the meter panel or breaker box say on the largest amp fuse / main shut off ?

  3. #3
    Join Date
    Jan 2011
    Location
    Columbiana, Alabama
    Posts
    623

    Default Re: Dimming lights

    If it just started, call the power company before an electrician.

    You may just have a defective crimp connection where they feed your house. Or, at the pole.
    Good Luck from Columbiana, Alabama
    Maurice Turgeon, Hidden Content

  4. #4
    Join Date
    Feb 2013
    Location
    Texas
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    Default Re: Dimming lights

    The outside box appears to have what I believe is called duplex breaker . They are 60 amps ea.
    Also have two other singles at 30 amp ea. I've never had to reset them . On the inside there are 4 fuses . I haven't had to replace any of those in quite a while , all 20 amp.

  5. #5
    Join Date
    Dec 2007
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    Tennessee
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    Default Re: Dimming lights

    The problem could be almost anywhere from the fuse box to the transformer on the pole outside. If this is a relatively new problem, I would look at the fuse box first, and since it is a fuse box, you really may need a replacement. The outside wiring comes to a pair of buss bars in the fuse box. If the connection of the outside wires to the buss bar gets corroded or loose, then you will get the kind of issues you are experiencing.

    With only 4 fuses in your fuse box, I don't think that you have as many dedicated circuits as you think. You should remove the fuses one at a time and map out what outlets, appliances and lights are affected by each one. Your microwave may be sharing a circuit with more things than you think.

    If the lights in question share the same fuse as the microwave and the washer, the issue could be the fuse connection itself. Just pulling the fuse and resetting it might clear up the problem.

    The reason the fuse is not blowing is resistance in the circuit. a connection that is going bad will develop more resistance than it should. Then when a load (light, microwave, etc) is turned on, that resistance drops some of the voltage. All the loads are in parallel, meaning that the loads are electrically side by side and not strung out in a row. Each time you add a load, more current goes through that resistance, which causes it to drop more voltage, so each load in turn gets less voltage. Hence the lights dim as you turn on appliances.

    semi-retired is right in that it could also be loose nut and bolt on the transformer or a loose connection in the meter box, especially if it is an old meter box. The power company can check those first, but if they are OK, you will need a licensed electrician.

    The short story is, you need a qualified electrician to look at this, and do not be surprised if the recommendation isn't for a new breaker panel to replace the old fuse box. BTW, I had an old breaker box in my house that started doing this and I ignored it too long. It eventually caught fire, fortunately the fire was contained inside the box and only lasted till the main breaker melted. Not much damage, just had to replace the breaker box. Mine was an older box that used an aluminum buss bar, back when they were allowed. Got a copper one now.
    Last edited by keith3267; 02-03-2013 at 02:01 PM.

  6. #6
    Join Date
    Feb 2013
    Location
    Suburban Chicago
    Posts
    13

    Default Re: Dimming lights

    Nice answer Keith. Well said.
    Joel @ The Renovation Place

    Check out my website at Hidden Content

  7. #7
    Join Date
    May 2008
    Location
    Pacific Northwet
    Posts
    1,361

    Default Re: Dimming lights

    Can you tell what brand the breaker is? There are some that are known to be prone to failure (in a bad way), particularly Zinsco and Federal Pacific Electric.

    This site has more information on the failure modes of those brands:

    www.ismypanelsafe.com
    The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.

  8. #8
    Join Date
    Feb 2013
    Location
    Texas
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    Thumbs up Re: Dimming lights

    Quote Originally Posted by tooltrader View Post
    My home was built in the 50's and has the original wiring .
    Just 3-4 days ago all the ceiling lights would dim as the microwave was turned on .
    I turned off all lights except for one and that still dimmed on microwave use . I have metal incased wiring under the house and wiring in the attic also . I believe the ceiling lights are separate from the wall plugs . The washer also causes this . I believe that the washer is on a dedicated circuit as it
    appears to have been run directly underground to the outside box .
    no breaker has tripped outside and no fuse has blown inside .
    Whats going on here ?

    I called the elect. company as advised . I got excellent response from them . The guy went to check and was back at the door with-in 1min. He said that it was obvious that the crimps were bad .
    When I got home that afternoon they had replaced the wires from the pole . NO MORE DIMMING . YAAAAHHHOOOOO !!!!!. I hope to help someone here as you fine people have done for me . THANKS again, Now about the roof !

  9. #9
    Join Date
    Dec 2007
    Location
    Tennessee
    Posts
    1,381

    Default Re: Dimming lights

    good call The Semi-Retired Electric. This is also beneficial to the utility company because a bad connection like this drives up the load losses of the transformer. Since the transformer is before the meter, these losses are borne by the utility company and not the customer, at least not directly.
    Last edited by keith3267; 02-07-2013 at 12:09 PM. Reason: correct spelling

  10. #10
    Join Date
    Jan 2011
    Location
    Columbiana, Alabama
    Posts
    623

    Default Re: Dimming lights

    Quote Originally Posted by tooltrader View Post
    I called the elect. company as advised . I got excellent response from them . The guy went to check and was back at the door with-in 1min. He said that it was obvious that the crimps were bad .
    When I got home that afternoon they had replaced the wires from the pole . NO MORE DIMMING . YAAAAHHHOOOOO !!!!!. I hope to help someone here as you fine people have done for me . THANKS again, Now about the roof !
    Glad everything worked out!
    Good Luck from Columbiana, Alabama
    Maurice Turgeon, Hidden Content

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