Bad Neutral?

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Praedatus1

Praedatus1

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Portland, Oregon
Okay so here's the story.... Workers doing street repair for water main took apart a water line going to a house, when he did, he got electrocuted when he bridged the pipes with his hands... we got called, I inspected and found this:
The panel has 3Wire SE back to back with meter, which is underground service...wires going out of meter to the pole are 4/0 4/0 2/0 and 35 feet away they go up the pole 2/0 2/0 #2 bare solid(neutral), so somewhere underground there must be a splice. The panel has a 1/2 emt pipe coming out the top and runs 5 feet to a waterpipe clamp with a #4 bare ground in it bonding the pipe. With the pipe clamp ON OR OFF, I get around HALF the house CURRENT measured through my amp-clamp meter. The rest of the basement is finished, so I do not know of another bond to the water, but there must be one buried somewhere. I took the bond clamp off and tried to measure voltage, and got 12 volts or so, but when I "touch" the clamp to the pipe there is sparking and it "hums" until tightened. Regardless, when the workers took the pipe apart, it IMMEDIATELY blew up the guy's washing machine and 2 surge suppressors on computer equip. FRIED and melted.
I am thinking the underground neutral is corroding apart and had just enough continuity to get some of the return current. When they took apart the water pipe the system went haywire and got weird voltages due to the loss of its "supplemental neutral"(although I dont think thats what water pipes are supposed to be, right?) ...The City of Portland says no way, the problem is ours. They also say that current on the water pipe is "normal"...Really?? Help!!
Tim
 
sorry my post is so long... this is quite the perplexing case for me... the city REFUSES to dig up the service, so I'm stuck troubleshooting it without that factor.
Tim
 
Are you saying you think there's an open neutral somewhere outside the house in a buried service lateral?

If so, time to get out a fault locator.
 
Fix these all of the time, the neutral is burned or corroded in half in the utilities cable. The transformer is bonded again at the pole or pad mount, which probally also feeds another residence. Since both residences are bonded to the cold water, the current had an alternate path, as soon as the plumber broke that path they became the new path. The other grounding electrode were of too high of resistance to offer an alternate path. The utility company around here have a portable 10 kva transformer on handtrucks that take the two good legs and change the staight 240 back to 120/240, not saying that this real safe, but is a temporary until the crew burys a new cable.
The utility company is tring to cover their butts, but most likely its their cable, unless it is customer owned/installed. Some utilitys the customer even has to supply the transformer.
 
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i dont think its completely burned through,,, but it is very hard to tell, the only bond I see in the panel I removed, and I still get current(and plenty of it) on the water pipe, so im not sure how to check without digging up the friggin service drop. I thought about doing a new service overhead and seeing if that solves it, but the city says no way.
 
yeah hillbilly1, I think that is the case here, I was just wondering if anyone else had seen it and found a different problem... the city semms to think we have a "hot" wire touching the waterline somewhere,,, they dont know anything about in-house electrical apparently. No breakers have ever tripped to my and the homeowners knowledge.
 
Wait.....someone was ELECTROCUTED and the city REFUSES to dig up the service?


I am hoping you meant "shocked".


When the grounded service conductor is broken the electrons will take whatever path is available. This is OBVIOUSLY the case here. When they removed the meter they took the only grounded path available and the 120 stuff became 240ized.;)



the city semms to think we have a "hot" wire touching the waterline somewhere,,
Click to expand...

This is stuff you learn about in yout first year. What city is this?
 
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well that tears it... i am going to meet the city out there tomorrow and show them the evidence. They must replace the underground or let us re-do it in overhead fashion.
thanks for the help guys.
 
if by lateral you mean the service drop, yes. If you mean the power, its PGE. I want to do an overhead b/c I think its the easiest fix (the guy has a ton of flowerbeds and nicely designed water features over the underground- I know it doesnt really matter, but still...) and an overhead would be fast. also, the pole-mount transformer is 300 feet away- the secondary runs across 2 poles to this house. So I am concerned for the neighbors regarding the current through the waterpipe. Its just not safe.
 
One of the problems with city services that are grounded to water pipes is that one house can lose its neutral and the water main then becomes a current carrying conductor. Everything goes back to the panel where grnd and neut are bonded and then through the water pipe back to the center tap of the POCO's transformer via someone else neutral conductor. Most of us know to be very carefull opening up ground connections but unfortunately others don't.It sure surprized me the first time I saw a water pipe spark.
 
A service lateral is underground. A service drop is overhead.

If it's PGEs line, why would the city get involved?

If the yard is so prized, have a new lateral bored in. But I would still start with a fault locator.
 
Bad Neutral,
There is a way to find it with a digital meter by connecting one end to the ground rod and the other end on a probe. Stick the probe end in the ground as you work toward the utility pole.
The voltage should increase (or is it decrease) as you get closer to the fault.
Somebody help me out here please!
 
oh sorry by "city" i mean pge, they do most of the city here. I guess that explains why they don't care. The city water workers probly just went home pissed instead of calling pge. The homeowner has been trying to get it resolved. I am meeting with them tomorrow and will plead our case. One way or another, the current service lateral is history.
 
220/221 said:
The landscapers damaged the insulation and it eventually turned to powder.
Click to expand...

A good guess, IMO
This is almost certainly an open neutral.
I can't believe the POCO won't do more with a death involved. (By the use of the term, "electrocuted", I am assuming the worker was killed.)
 
This is why i hear that some plumbers/pipefitters, want to change the NEC with the using the water pipe to the house as a GEC. They sometimes have to change them to plastic when repairing and they get shocked.

So what do you think of the NEC changing the water pipe from being used as the GEC?? Making people use more ground rods or ring or plates as the GEC.
 
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