Three or four years ago, my church set up a summer camp retreat.
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?

--

Christopher A. Young
You can't shout down a troll.
You have to starve them.
..