117V to earth

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Fred B

Fred B

Senior Member
Location
Upstate, NY
Occupation
Electrician
Called in for service call on an old mobile home for a water heater fire. Water heater breaker never tripped. Owner shut off breaker when they saw smoke coming out from where water heater was. Partner went in ahead of me and when he reached for the door he got zapped. Immediately metered from metal siding to earth (literally the dirt) and got the 117V reading. Is this a problem? Owner didn't think so.
 
Fred B said:
Called in for service call on an old mobile home for a water heater fire. Water heater breaker never tripped. Owner shut off breaker when they saw smoke coming out from where water heater was. Partner went in ahead of me and when he reached for the door he got zapped. Immediately metered from metal siding to earth (literally the dirt) and got the 117V reading. Is this a problem? Owner didn't think so.
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So, ... what happened? Get run off or ... ?
 
oldsparky52 said:
So, ... what happened? Get run off or ... ?
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No, found offending circuit and turned it off. Tried to explain the level of power that represented. While may not be 100% accurate in that don't know the amperage potential but told her that she could take her TV and plug it into the sidings and power it. She understood that she wouldn't think of putting her finger in the outlet for the TV.
 
My wonder is why breaker wouldn't trip. Would or could the breaker maybe trip if I took a lead from trailer siding and a grounding conductor? Could this be a symptom of a failed or missing bonding of trailer frame?
In addition to the electrical issues it has substantial structural issues including what led to the water heater fire. Water heater fell thru floor stretching and shorting the conductors. It just never tripped the breaker for the water heater though. A breaker did trip that had circuit on the same side of trailer as water heater. I believe if a building inspector saw the home it would be condemned.
 
My uncle had an old mobile home that he moved to a different park and wanted me to wire it up to the pedestal. Turned the power on, one of the breakers tripped. He said it didn’t do that at the other park. I told him he has a fault in that circuit, and his trailer probably wasn’t grounded at the other park. Tracked it down to a light in the hallway. He had changed out that light a few years back, and tied the ground and the hot together!
 
I'll assume the trailer had the power not the earth. If so then the siding obviously is not bonded to the frame of the trailer. If you know what circuit then trace it out. Someone probably drove a nail thru the siding into the wire. It actually could be many things...
 
Dennis Alwon said:
I'll assume the trailer had the power not the earth. If so then the siding obviously is not bonded to the frame of the trailer. If you know what circuit then trace it out. Someone probably drove a nail thru the siding into the wire. It actually could be many things...
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Or the frame was not bonded……..see a lot of trailers with only three wires ran from the pedestal or service pole. Ever time I get a call from someone who is getting shocked from their trailer door, I know the reason right off the bat!
 
Dennis Alwon said:
I'll assume the trailer had the power not the earth. If so then the siding obviously is not bonded to the frame of the trailer. If you know what circuit then trace it out. Someone probably drove a nail thru the siding into the wire. It actually could be many things...
Click to expand...
Isolated the circuit. Breaker off, siding voltage gone. Part of circuit on same side as water heater that dropped through the floor, outside wall also buckled out in same location as water heater. Not sure on mobile homes the wiring of circuits, they never made any sense to me as to coordination of location.
readydave8 said:
which circuit was it? I've found similar on bathroom receptacle circuits that include exterior receptacles, and one underneath for heat tape
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It was on a circuit that included part of a bedroom (same that had water heater in the closet), part of the living room, kitchen lights and the refrigerator.
 
Fred B said:
Isolated the circuit. Breaker off, siding voltage gone. Part of circuit on same side as water heater that dropped through the floor, outside wall also buckled out in same location as water heater. Not sure on mobile homes the wiring of circuits, they never made any sense to me as to coordination of location.

It was on a circuit that included part of a bedroom (same that had water heater in the closet), part of the living room, kitchen lights and the refrigerator.
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You're correct, wiring in mobile homes sometimes makes no logical sense in both the direction run and what is on what circuits.
I think you may have had one or both of two problems,
1) water heater was not bonded to the EGC
2) trailer frame was not bonded to the EGC
Possibility of a 3rd problem, no EGC ran from the outside disconnect.
 
ptonsparky said:
OP. You win the prize. I’ve never had some one call me to help with any thing that fell through the floor.
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Unfortunately typical of old mobile homes, floors rot out and equipment goes thru. This one, one of the more extreme that I've been called to "repair". Seen one the refrigerator went thru the floor, and more than a few toilets.
 
Fred B said:
Unfortunately typical of old mobile homes, floors rot out and equipment goes thru. This one, one of the more extreme that I've been called to "repair". Seen one the refrigerator went thru the floor, and more than a few toilets.
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Hope nobody was on them lol.
 
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