On Mon, 11 Jun 2007 16:40:39 -0000, BobK207
wrote:

On Jun 11, 8:02 am, dpb wrote:
Stormin Mormon wrote:

...



They built a mess hall, cabins, and a couple shower and toilet
buildings. Cement slab, wood frame walls. Shingled roof.

The campers are complaining that when they touch the shower
handle, they can feel an electrical tingle. The WH is propane gas
fired. The propane line (black iron) also goes to a Rheem Contour
furnace, which supplies an overhead heat duct.

I took a VOM and length of copper pipe, used that to check from
the shower handle to the drain. Got 5 volts AC. Doesn't happen
when the power is switched off for the furnace.

I traced the wiring, the furnace was only put in a year or two
ago. (Nobody complained about shocks until the new furnace was
put in.) New, shiny copper wires. I pulled the wire nuts on the
neutral and ground. The wires are clean, adequately stripped
back, and the wire nuts get a good "bite". The panel box, like
the rest of the building is only two or three years old, and nice
and new.

The WH has dielectric thread connections at the top, I can see
the red plastic at the fitting. From what I can tell, the water
main coming out of the ground is plastic.

The questions a

1) Why would a brand new furnace be leaking power? And how's it
getting into the shower? The only other electrical devices in the
building are lights, and a couple electric sockets.

2) Why isn't the power going out the neutral and ground?

3) How to safely take care of the problem so the campers aren't
being shocked?

My thoughts at the moment, are that the neutral / ground has some
corrosion or resistance past the panel. Meaning outside the
building. And that the solution is to run a new ground wire out
the wall, and sink a ground stake right outside the wall with the
panel box. Any other thoughts of how to handle this shocking
problem?

You have, almost certainly, a grounding issue. My first thought w/
separate buildings an auxiliary ground is inadequate/missing, but with
only a general description not possible to tell much specific.

Need to know how the power is distributed and where the ground(s) are.
I'd be a little concerned that your measurement of the voltage is an
underestimate from the technique to reach so I'd treat this as a
potentially (pun not intended) serious issue. Probably adding a ground
directly at the shower head as a temporary pallative would help. Surely
there's a good electrician-type in the church that
can help diagnose this? Distributed system grounds can be very
difficult to trace and a pro should be able to recognize where there's a
problem if a needed ground is missing.

--


All-

Some comments & more questions than answers.......


Sounds like he's got a grounding problem but desn't he also have a
problem in the furnace itself?

the resistance from the grounding system to the earth is too high?

& the "ground path" from the grounding system to plumbing, instead of
grounding the shower plumbing is actually "hotting it"

but isn't the real problem in the furnace? some how is the power
leaking over to furnace frame & thereby "hotting" the furnace frame &
ground?

now you've got some juice in the (inadequate?) ground system that is
trying to find it's way back to earth.......the shower plumbing & the
showerers are part of this ad hoc path.

shouldn't the fault (nsulation? wire contacting bare metal?) in the
furnace be looked into? maybe a fault in the blower motor?

Grounding is part of the issue but isn't the source of the voltage of
equal importance?


cheers
Bob

The first thing he should do is completely disconnect the furnace.
The switch shuts off the HOT. But open the box and disconnect the
neutral too. Then see if you get a shock or voltage reading. If not,
there is an electrical leak, bad motor or something else. If there is
still voltage in the shower, the problem is not the furnace.

You did not mention what kind of pipe feeds that shower. Is it
copper, steel or pvc or some other plastic? If it's copper, or steel
ground the pipes to a good ground. If its a type of plastic, some
wire has to be touching the shower valve. It could be someone
punctured a romex cable with a nail and it's leaking into something
metal touching the shower valves.

On the other hand, it could be the drain that is getting the voltage.
I dont think anyone uses metalic pipe for drainage these days. Thus,
with pvc pipes, the voltage it leaking into the drain, or the tub
itself if it's a metal tub.

Here's another test. Shut off the MAINS in thge breaker box. Do you
still get a shock? If not, turn on the mains and turn off each
breaker one by one till you find the one that kills the shock. Trace
that entire circuit. I'd guess it does to that bathroom.

Of course, since this is a church project, it could be that the man
upstairs is just having a little fun, or maybe he needs more people in
heaven. So, if all else fails, blame God.

T8EPLO96