On Sat, 11 Oct 2014 21:26:22 -0400, "Robert Green"
wrote:

"John G" wrote in message On Saturday,
October 11, 2014 10:00:19 AM UTC-4, Robert Green wrote
in message
wrote:

In that case the ground wire did NOT go back to the panel, but to a
clamp on a cold water pipe.

Until the 70s that was legal.

But stupid. And that's why they outlawed the practice. The wire went off
to parts unknown (in my case) and some small amount of current leakage
apparently caused galvanic corrosion to occur where it lamped to the
waterpipe. It caused a pinhole leaked to develop. All tucked away
behind a stapled ceiling and hard to find without making a mess.
In my mind, those are two good reasons why they changed the code and
why such connections should be removed and done according to modern
rules whenever they are discovered even if they are still grandfathered.

As for the OP, what was legal in the 70's is moot.

*Actually the 2014 code does still permit the connection to the waterpipe.
Article 250.130(C)(1) states that is is permitted "At any accessible point
on the grounding electrode system as described in 250.50". The waterpipe is
part of the grounding electrode system. The water meter and water heater
bonding jumpers would have to be in place and the clamp would need to be
approved for the type of metal piping.

I really don't want to dive into this can of worms again so I'll just note
all the potential failure points of using a clamping method from the code
fragment you cited and I'll bet many more live in 250.50:

The waterpipe is part of the grounding electrode system

IF and only if

1) The water meter is jumpered

2) the water heater is jumpered

3) any section of the pipe that's been replaced by pex or plastic is
jumpered

4) the right kind of clamp is used that won't cause galvanic corrosion

I would add that the wire from the outlet box is labeled as to where it's
going off to. When I checked the outlet and it failed, opening the box was
no help. When I tried to trace the cable back to the panel with a fox and
hound I couldn't tell where the ground wire was going because it was stapled
high inside the joist (badly stapled, I might add).

I removed one stapled ceiling tile (what a mess that was - so much so it
helped lead to taking the whole damn ceiling down) and saw the wire going
off at 90 degrees from the main cable. Tracing that proved to be impossible
with the fox and hound so that aided in the decision to pull more tiles
(this was a critical outlet for power tools in the workshop). The readings
on the tester were flakey. Sometimes it would be grounded, other times the
test lamp would flicker or extinguish completely, especially if there was a
load on the second outlet of the receptable in question.

It's just my opinion, obviously, but a wire that's used primarily as a
life-saving measure going off to parts unknown should have a "good"
provenance. It was obviously NOT done by an electrician because of how
poorly the wiring was connected - it was nicked and barely under the screw
and not stapled near the box. Another clue was that it was 10 feet FROM the
damn panel and done when the ceiling wasn't in place so a real sparky would
have just run a new wire and breaker (and they did for the window air
conditioner outlet that was clearly added on at some point).

Tote all the potential failure points up and it's clear using a pipe as a
ground has lots of potential risk - at least compared to pulling new wire.
I understand why it was grandfathered: I am sure the NEC weenies feel that
any form of grounding is better than no grounding at all.

Many of the outlets in the house were three-pronged but NOT grounded, FWIW,
another sign of a rank amateur. Still with the basement open it would have
been simple to do it right and after pulling the ceiling that's what I did.
Replaced all the old outlets that I found that had three prongs but no
actuall ground connection with new two pronged ones and ran all new circuits
to areas that were critical - along with GFCI's.

This was 1940's cloth covered wiring and I am sure oxidation of the
conductor along has slightly degraded its ampacity.

That is what I think happened in your case. The disimilar metals of the
ground clamp (Brass) attached to a steel pipe acted as a battery.

FWIW, it was a plated steel clamp on a copper pipe - same thing really.

Just like a water heater. The clamp should not have been buried in a
finished ceiling. The ground wire should have been run over to the water
meter location where it would have been accessible and could have been
clamped to the water pipe or the grounding electrode conductor.

I think you're 100% correct about how that happened. Obviously none of this
work was ever inspected - properly at least - and the only good thing about
all this jack-legging was I got to knock a few thousand off my offer after
doing a walkthrough of the house with my outlet tester. I recall the
comment "We had a lot of appliances that had three prongs so my son replaced
the old two prong outlets so we didn't have to use those adapters anymore."
The sounded proud that he could do it! I really don't think they understood
the ramifications of using 3 prong outlets on ungrounded circuits. Someone
did, eventually, which is why the green wire to the basement outlet
eventually appeared. I believe he had installed new shop lights that needed
a ground to operate properly.

The wiring in this house ran up to the attic and then down again like
octopus tentacles inside hard plaster walls so running a ground wire along
the original cables (or pulling new wire) just wouldn't be feasible. And
that's why I can understand the NEC rules about waterpipe clamps.

So I ran new 12/2 w/ground and GFCI's to the window AC's, the outside of the
house, the kitchen and the office and used dual skinny breakers to wire them
to the panel. For the most part, only very light loads are now running off
the old wiring. Much of it is CFL lighting, further reducing the risk of
overloading the old wires and in most cases, not needing a ground wire
anyway.

At first I was concerned that I had too many dual breakers, but the electric
consumption has dropped slightly each year as I retired plasma TV's for LED
TVs, 30 year old refrigerators for new high eff. ones, CFLs for tungsten
lighting, etc. So it's clear that even though I have more circuits than
before, the total load on the panel is actually lower than it's been
historically.

I'll save it for another thread but my neighbor's electrician son solved a
very interesting puzzle in which some of the lights in his mom's house went
off for several hours early in the AM and then came back on by themselves
without resetting any breakers or GFCI's. I couldn't diagnose it, and
neither could he until I told him that a single UPS's started chirping at
3AM, which I thought was low voltage but seemed to be battery failure., so I
got up and shut it off. No other UPSs beeped so I assumed it was a local
event until my neighbor told me about her basement tenant's lights going
out, too. When I restored power to the UPS and turned it back on the next
day, everything was fine and the battery tested out as good - I was about to
replace it just in case but it was less than a year old.

You've got good analytical skills, John. What do you think it was? (-:
I'm waiting to hear this one!! I'll bet it was something so simple
we'll all say "duh" and whack out foreheads when we hear it.