On Thu, 09 Sep 2004 17:04:08 GMT, Walter Maxwell wrote:

|On Thu, 09 Sep 2004 08:41:17 -0700, Wes Stewart wrote:
|
|On Thu, 09 Sep 2004 15:10:28 GMT, Gary S. Idontwantspam@net wrote:
|[snip]
||In industrial situations, I have had to deal with ground loop
||problems, which are a PITA to find. Do your grounding correctly, and
||you will be safer, and have an easier time of it.
|
|You should have seen the problems I had when I had the house
|electricians wiring up an r-f shielded room. Trying to convince them
|that they had to run just *one* ground wire from a single point on the
|room to a building ground and not the service entrance ground *and*
|that the wire couldn't be bare and laying on the sprinkler system
|piping, the A/C ducts and electrical conduit in the overhead.
|
|Then fighting off the fire department guys that insisted that they
|were going to run a pipe into the room for sprinklers.
|
|Apparently the electricians only knowledge of 'loop' was in 'loophole'.

Yep. To elaborate. The building (100,000 sq ft) was constructed of
tip-up concrete exterior walls and steel columns and roof trusses. A
few of the columns, were dedicated ground points, complete with copper
plates for wire attachement. They were bonded to the steel rebar grid
in the concrete slab-on-grade floor.

All of the A/C conductors into the room, neutral included, ran through
some real hefty line filters that were on the outside of the room with
feedthrus into a distribution box inside. On top of the room was a
single copper stud for ground connection.

As I said earlier, the electricians wanted to ground the room with the
usual A/C distribution safety ground wire. When I said no, they
needed to go to the nearest column ground, they ran a 6 AWG bare
copper wire to the grounding plate. Of course the wire was in contact
with everything it contacted.

So when I saw this I said no, you have to run an insulated wire. So
the next iteration was a single green wire. I said no, some bozo
plumber (I shouldn't say this, my brother's a plumber) or HVAC guy
will be up there working and the wire will be in the way and they'll
cut it and my room with be a 100 or so V above ground due to all of
the capacitors in the filters. I finally got my insulated wire in
conduit.

Then the HVAC guys wanted to run a steel duct to the room. Noooo, use
an insulated collar and give me a pneumatic thermostat.

Then as mentioned earlier, it was the fire department. They saw all
of the handy pipes running through my feedthru panel (actually
waveguide below cutoff feedthrus) and said we can just plumb in the
water through one of these. Nooo, can't have a metallic connection.
So they say, they can use a dielectric union. Nooo, the water in
those pipes hasn't moved in 20 years and is primarily rust.

When they started talking about halon I said that my widow was going
to have a real good time with the millions she would get from the
lawsuit. They decided that the regular sprinkler system above the
shielded room was okay afterall.