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Thread: Really weird short/ground situation

  1. #1
    Join Date
    Jun 2018

    Default Really weird short/ground situation

    Hello all, I have a few questions and hopefully, you have some answers. I live in a mobile home, 1980's vintage, with some writing difficulties. I heat with propane and electric. Last winter, I noticed the
    lights in my bedroom flicker and get dimmer. I checked around the house and the breaker box and nothing was burned out or broken or tripped. But the lights in the bedroom and kitchen were still a little dim. I checked the heaters and the outlet one of them was plugged into was a little discolored. I checked it with a meter and it read 78 volts. I started checking other outlets and about half the house read the same(75-90 volts). The effected outlets appeared on four separate circuits. Including two 220v circuits. The dryer will not function and the hot water heater is so-so( like its running on 110?) Also, the washer, on a 110 circuit, won't start. Everything in the breaker box seems normal. The breakers all control their respective circuits. Except the hot water heater. If I trip that, all four circuits die.

    Obviously, that hot water circuit is key to this whole thing and I have an open circuit somewhere but why would it effect four. And especially two 220s and two 110s. I know trailer writing is notoriously crappy but this one is from a reputable manufacturer who's still in business but no wiring diagrams exist for my house.

    I've always done my own electrical and would like to fix this myself but I'm stumped as to what's going on and I don't want to start tearing into walls only to find that that's not where the problem lies.

    Any thoughts, suggestions, comments would be greatly appreciated. Thank you in advance for your time.

    Also, would this type of situation drive up the electric bill? Mine are out of control. Like double normal. I did use a few new appliances last winter but no dryer and the water heater is iffy. Less lights, too. Thanks again!


  2. #2
    Join Date
    Feb 2012
    Lala land, OH


    Start at your dryer since you have a meter. Measure from one of the hot's to neutral, then measure from the other hot to the neutral. Those numbers should be close to being the same.. A little off isnt too bad. but 78v is approx 40v lower..

    If you have a loose neutral situation then that would mean your other side is about 160V.. That's bad! This would also mean that some lights are getting brighter when others are getting dim. This will fry electronics and the low voltage can burn up motors.
    This could be in your trailer electrical panel (your responsibility if you own the trailer) or could be outside in your service (which could be the responsibility of the utility and/or the landlord (if you are in a place like a trailer park)) If you have a management company or landlord, call them first.. If not, call your utility, they usually don't charge to inspect it, but they usually wont or cant go past your meter.

    The other scenario that you could have is that you have low voltage on one leg, and the other leg is still 120V hot to neutral.. This is a issue with a hot leg or service conductor.. The areas that it could occur in are the same as above.. This is dangerous in another way.. Something is loose and acting as a resistor which is generating heat. This is a major fire hazard.

    If the issue is in your panel it is usually on the service side of the main breaker which means you either will need to pull your meter or flip a disconnect if you have one at the meter, (between the meter and that disconnect would still be inaccessible)

    If you have the trailer style outlets that snap together without a box it may be time to rewire.. Those have been known to fail.

    Unplug any electronics and large draw devices until this is looked at.

  3. #3
    Join Date
    Feb 2012
    Kent, WA


    A few further comments:

    When you are measuring the low voltage (e.g. around 80V), go to the panel and measure the voltages at the circuit breaker output for that circuit. If the voltage at the breaker is low, then move up to the two lugs feeding the panel and see if one of those is low. If it is, then repeat the test at the meter. Be extremely careful with your meter probes when poking around these large lugs and in the meter -- a lot of current is available here and can make huge sparks and fireballs. Wherever you find the low voltage, but it is normal upstream, is where the poor connection is (the first place where the voltage reduces).

    If the voltage at the breaker is fine, then you have a poor connection in the branch circuit somewhere. I'd reterminate the receptacle. A dryer and water heater should be dedicated circuits. If you see extra wires in either of those boxes, then someone has extended them to other rooms which is a problem because these are usually 30A circuits and I'll bet there are no 30A outlets anywhere else... Also look in the breaker panel for extra wires coming off these breakers.

    When testing for this lower voltage, you most likely need some load on the circuit to drag the voltage down. A high resistance circuit with no load (other than the micro amp the meter draws) will not show up as a reduced voltage. The more current you suck through a bad connection, the more the voltage will drop (and the more heat will be produced).

    I'm thinking since you use space heaters, someone has tapped off the water heater circuit to other rooms because most 15A circuit are going to trip with a space heaters if you're running other stuff on that circuit. Even worse would be if they paralleled the water heater and dryer circuits. Space heaters are a tough load for marginal wiring to accommodate. If you use them, I'd look for ones that are under 1000 watts (many have switches such as a 900W element and a 600W element -- just use one or the other but not both). These connections are probably poorly made and will catch fire if you don't fix them.
    Last edited by suemarkp; 06-16-2018 at 11:51 PM.
    Kent, WA

  4. #4
    Join Date
    Jan 2014
    Central Minnesota


    Does the power come to your trailer house underground?

    You got me when you said your electric bill is out of control. A lot of times when you have a bad wire underground, the current is actually flowing from hot to the earth-dirt (since the system is grounded). What I try to explain to people is the power is "leaking" kind of like water. It is going somewhere, drawing current and spinning the meter, but giving you nothing. This generally starts as a break in the insulation on a directly buried wire. It gets worse until you loose power. When I dig the bad spots up I find the aluminum conductor has turned to white powder. The only reason I bring this up is generally the power to a trailer house is a service on a pole (or freestanding pedestal if the service is underground from the utility), but most of the time it goes underground from that point under your trailer to the panel inside. Between those two places is where I would look. I bet the power is fine at the main breaker on the pole or pedestal.

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