Stray Voltage?

[ken44]

I just got back from trying to troubleshoot a problem that a customer was having at the electrical service of a recently purchased repossessed mobile home, they called me because lamps started blowing out when they went to turn on the switches. When I arrived I turned on power at the meter(200 amp service with the grounded conductor being grounded by means of a split bolt to the wire that was going up the pole to the transformer) and checked line and load voltages, everything was in order at the pole, however when I went to the panelboard, I found 230 volts from "A" phase to neutral explaining the burning lamp problem, at this point I had not turned the 200 amp breaker in the mobile home panel on yet, with it still off, I went outside to see the ground rod and wire, the person who did the work had put a plumbing fitting in line with the electrical PVC that had a hole in it and they ran the solid ground wire and the A/C wire out of that hole, then the ground wire was connected a ground rod sticking 16" out of the ground and clamped by means of a rubber hose clamp! I touched the rod and got a shock, there was 60 volts from the ground rod to the earth, I keep getting a continuity reading of zero ohms between one ground bar and the "A" phase wire and when I go to the other side of the ground bar to "A" phase with my ohmmeter, I get around 400 ohms. Alot of weird stuff going on, can anyone help. The panel in the mobile home is a 200 amp siemens panel. The service at the pole is a 200 amp GE and was done poorly by the utility company, they used 20' of EMT going up the pole, there are no screws in the meter box at all and only one screw in the GE can.

 

[tom baker]

Re: Stray Voltage?

Take lots of pictures
Is there a main bonding jumper?

 

[pierre]

Re: Stray Voltage?

It is difficult at best, to help with your situation online, but it seems as though your grounded conductor (neutral) is energized. I would have the POCO at the site to check their side.

Pierre

 

[ken44]

Re: Stray Voltage?

I had to install a main bonding jumper, there was not one there when I arrived and upon getting shocked by the ground rod, I went straight to the pole to check that out.

 

[hurk27]

Re: Stray Voltage?

Ken a trailer has to be fed by a 4-wire feeder ran from either the disconnect within 30' or if the main service is within the 30' requirement then it must be ran from there. the grounding and grounded conductors should only be bonded in the main service or the disconnect. Not in the panel in the trailer. If you had voltage upon the grounding of this trailer then either something is using the grounding conductor for a return path which only had a rod for a return path or the electric dryer has the heating element that went to ground. or the something but with the electric water heater.
Look at your other post on this and read my reply
one of the reason's for this requirement is that with a 200' run you will have a voltage drop. and if a child is playing out side and happens to be touching the siding and standing bare foot in water and a fault in one of the circuits was to occur this child will have to full voltage of the voltage drop across him/her. This is why it is important to keep grounding and grounded conductors separate. This has been in the NEC and the HUD codes (3280) for a long time, and has been a very common violation that is done by unqualified trailer setup crews. Just remember isolated grounding in the trailer panel. This isolates the current carrying neutral from the non-current carrying grounding of this trailer. But a grounding conductor will have to be ran back to a disconect located no father than 30' from teh trailer and a grounding electrode will have to be installed at this disconect and at the trailer by where the feeders enter the trailer. This GE can be bonded to the fram or ran inside to the panel.
Just one other note is any grounding conductor has to be insulated and be green.

[ August 20, 2004, 09:36 PM: Message edited by: hurk27 ]

 

[jimwalker]

Re: Stray Voltage?

If your saying it is 3 wire 200 feet away and goes directly into trailer panel then this oviously was never permitted and inspected.Needs fixed fast.

 

[josidasilva]

Re: Stray Voltage?

Grounding on single phase 240 volt transformer is essential for safety purposes, otherwise you may read up to 120 Volts between 'neutral' and ground.
See wiring diagram at:

(http://ecatalog.squared.com/pubs/Electrical%20Distribution/Low%20Voltage%20Transformers/General%20Purpose%20Transformers%20(7400)/3590.pdf)