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Thread: Acceptable voltage drop or bad connection(s)?

  1. #1
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    Acceptable voltage drop or bad connection(s)?

    I had a customer complain about lights flickering. Upon investigation, it seems that the lights flicker while his wife was using an iron in their bedroom.

    So, I took some measurements:

    Voltage in bedroom with several lamps lit: 120
    Voltage measured with iron on too: 105

    I checked the Volts and Amps at the panel as well:

    Lamps only: 122 Volts, 2 Amps
    Lamps w/iron: 120 Volts, 9.5 Amps

    So, there seems to be a 15 Volt difference from the panel to the outlet(s) in the bedroom.

    I figure that there is about 125-150 feet of 14/2 NM cable involved.

    This is a "double-wide" home, so there is a "crossover" connection underneath, as well as those nasty non-box outlets. Which means you can't check their internal connections without tearing them apart.

    I figure that the best remedy here is to remove all those non-box devices, install some boxes, and then use some real duplex outlets. Same goes for that plug-in crossover: Cut it out and hard-wire a permanent connection.

    What should be the voltage drop on a circuit with 150 feet of 14/2 and a load of 9.5 Amps?

  2. #2
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    The volt drop should be about half of what you are seeing.

    Here is a good volt drop calculator:

    http://www.electrician2.com/calculat...culatoradv.htm
    Advise is a dangerous gift, even from the wise to the wise.

  3. #3
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    Thanks for the link. I knew there were some out there, but didn't have time to manually calculate it, or search for the links.

  4. #4
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    Your number comes up at 6.5% VD for me.
    Voltage drop under 3% (3.7 volts) is not possible w/ #14 over 70ft
    Tearing out walls & devices for perfect connections will not fix this piss-poor design.

    Sharing lights & plugs on same circuit is a cost-cutting measure, but doing it with #14 is really cheep.
    Running 150ft of #14 with lights & plugs on the same circuit was just plain stupid.
    Last edited by ramsy; 03-30-12 at 07:48 PM.
    Roger Ramjet NoFixNoPay

  5. #5
    I would not blow this off as a simple voltage drop problem. Start pulling devices and looking for loose connections.

  6. #6
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    Bad connects will get hot because bad connection introduce resistance into the circuit.

  7. #7
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    bad thing about those trailer box's is taking it apart all the wire fall out of it, good thing is most of them are feed through meaning the conductors are not cut but a piercing device just Perice's the insulation to make contact, but you will have some with more then one NM running through it, and this is where a connection can be lost, but like you said, jump over connections can also be a problem, easy way to check as to where it is, just measure the voltage at each receptacle, or feel for a hot receptacle while iron is on.
    Wayne A. From: N.W.Indiana
    Be Fair, Be Safe
    Just don't be fairly safe

  8. #8
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    Quote Originally Posted by ramsy View Post
    ...Tearing out walls & devices for perfect connections will not fix this piss-poor design....
    Who said anything about tearing out walls? These devices are self-contained, and as such you can't check the connections without literally destroying them. But it's a simple task to remove `em, cut out the hole a bit larger for a standard pop-in box, and install a real duplex receptacle in its place.

    Time-consuming, but simple, and no patchwork should be required.

    My estimate of 150 feet for the circuit includes the home run, the crossover, and all the loops required around the room to encompass the entire circuit. It's probably less, but I was liberal in my overall estimate. Typical for any bedroom circuit in a decent sized house.

  9. #9
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    Quote Originally Posted by kbsparky View Post
    Typical for any bedroom circuit in a decent sized house.
    Where is it typical to combine lighting & plugs on #14, much less over 100ft long? How do you access factory NM junctions that don't require boxes?
    Last edited by ramsy; 03-31-12 at 07:12 PM.
    Roger Ramjet NoFixNoPay

  10. #10
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    Ask them if they want a receptacle at the panel, only one solution.

    You'd need to load all the circuits to find the loose noodle... What do they want to pay for QA, Service or Repair ?

    If your even thirsty, your two quarts low.

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