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Thread: Magnetic fields, mains hum, and one quacky garage

  1. #1
    Join Date
    Feb 2015

    Default Magnetic fields, mains hum, and one quacky garage

    Hello, new to forums & electrical, but have some basic knowledge.

    2+ years terrible magnetic fields and terrible mains hum in "parents" house and garage. Im 25, was on my way to moving out of the house and was then struck with a horrible sickness that i think is electrical related....but thats a whole different story, at this point taken any and all help.

    100 AMP main service in house. detatched garage 60 ft away supplied by a 20 amp single pole breaker using 14-2 romex UF W-G in metallic conduit. Ths subpanel feeding this garage is an old school screw in rated at 60 amps where the overhead lights are on one fuse, outlets on another, and a freezer on another. When observing the subpanel there is a hot jumper across the set of 4 fuses from one side to another. No ground rod driven at garage and the neutrals and grounds are tied together. I have water, gas, sewer and phone (with its own seperate uffer not bonded to the main grounding system) in between both structures. At the main panel the green wire that exited from the panel to the grounding electrode has also been "snipped" somehow, but according to pop's thats why you have your grounded neutral. And directly behind the garage two feet away are the edison, phone and cable lines.

    Now call me crazy... because my dad just cant seem to get enough of that in. "la la la we been hear 30 years and havent had any problems get off the drugs kid"... but the person who wired this garage back in the late 70's had one to many old milwaukee's when doing this weekend job , and isn't that copper wire from the ground bus to the electrode essential in tripping a breaker?

    Any help would be greatly appreciated as where to begin with something like this.. Currently i have seperated the neutral and grounds and isolated the neutral bus as it was all bonded to the enclosure, and installed a simple light switch before this whole mess just to be on the safe side. The 20 amp breaker in the house used to trip when using too much in the garage but now the fuses just melt in the garage and I get the faint smell of burning insulation underground every now and then.
    Attached Thumbnails Attached Thumbnails Magnetic fields, mains hum, and one quacky garage-img_0110-jpg   Magnetic fields, mains hum, and one quacky garage-img_0109-jpg  

  2. #2
    Join Date
    Feb 2012
    Welland Ontario


    1. 14/2 is only rated for 15 amps so the first problem is the 20 amp breaker in the main. It should be changed to a 15 amp.
    2. The grounding electrode has nothing to do with tripping breakers. That is what the neutral ground bond is for.
    3. The jumper is because you can only get 120 volts from a 14/2 cable. The jumper is connecting the other side of the panel together to compensate for the lack of a second hot wire in the feed. Not really a problem. With out it only half the fuse slots would be live.
    4. Since you only have a three wire feed the ground neutral bond in the garage is OK. It was code back in the 70s when this was done. You should add a ground rod at the garage.
    5. The overloads make it sound like you really need a larger feed to the garage. Use a four wire feed and separate the ground and neutral.
    Last edited by chrisb; 02-21-2015 at 09:24 AM.
    Operation Overlord.

  3. #3
    Join Date
    Feb 2012
    Kent, WA


    To add:
    • Romex isn't allowed outside, even in conduits. You should use individual wet rated conductors or UF cable.
    • A single 20A circuit to an outbuilding doesn't need a ground electrode system. But if you have a feeder (i.e. that wire from the house is landing in a fuse or breaker panel in the garage), then you are supposed to have a ground electrode system at that detached garage. The benefit is dubious, but code requires it. The main reason is dissipation of induced lightning voltages.
    • None of this should be causing magnetic field problems. That is usually caused by older knob-and-tube wiring installations where there is a lot of space between the wires of a circuit. Modern methods put all the wires in a single cable where they are all close together. This cancels out the field.
    Kent, WA

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