Current on Cold Water Bonding Conductor

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Karl H

Senior Member
Location
San Diego,CA
I have a building with a 1200I service 277/480.I understand that a

small amount of current on the GEC is normal. This building has

3I on the cold water bonding conductor.I took this reading with

a Fluke33 ammeter.What is a "Normal" amount of current on a cold water

bond? When the levels exceed the "Normal" levels.What are some "Normal"

causes? The current on this bond is'nt steady there is fluctuation.

All transformers in the building are bonded to this cold water pipe.

I have a few ideas but,I'd like to see what you guys might have to offer.

BTW my test was taken on the bond where it enters the service and on the

pipe itself at different locations.
 
Assuming this is a metal underground water piping system that also serves other buildings in the area, the water pipe is in parallel with the grounded conductor and it is not uncommon to have 20% or more of the grounded conductor current on the water pipe. This current would be on the street side of the water pipe grounding connection. Current on the building side of this point is often caused by illegal load side neutral to grounding connections.
 
don_resqcapt19 said:
Assuming this is a metal underground water piping system that also serves other buildings in the area, the water pipe is in parallel with the grounded conductor and it is not uncommon to have 20% or more of the grounded conductor current on the water pipe. This current would be on the street side of the water pipe grounding connection. Current on the building side of this point is often caused by illegal load side neutral to grounding connections.
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THat's what i would have thought. The building that has the current has

it's own PMT and the building next to it also has it's own PMT.All connections

as far as I can tell are made inside the building.Not a connection within

5' of the building senerio.Just simply a bond.I have not seen a illegal

neutral bond yet.I have been looking.Until I arrived none of the transformers

had a connection to XO to EGC's just primary to case bonds.I bonded all

XO's to EGC's. That's when I noticed the current on the cold water bond.

I also noticed current on other metal parts throughout the building.
 
Karl H said:
That's what i would have thought. The building that has the current has

it's own PMT and the building next to it also has it's own PMT.All connections

as far as I can tell are made inside the building.Not a connection within

5' of the building scenario.Just simply a bond.I have not seen a illegal

neutral bond yet.I have been looking.Until I arrived none of the transformers

had a connection to XO to EGC's just primary to case bonds.I bonded all

XO's to EGC's. That's when I noticed the current on the cold water bond.

I also noticed current on other metal parts throughout the building.
Click to expand...
Karl, please quit hitting the return at the end of each line. Your text will automatically wrap and it will be easier to read like this:

That's what i would have thought. The building that has the current has it's own PMT and the building next to it also has it's own PMT. All connections as far as I can tell are made inside the building.Not a connection within 5' of the building scenario.Just simply a bond. I have not seen a illegal neutral bond yet. I have been looking.Until I arrived none of the transformers had a connection to XO to EGC's just primary to case bonds. I bonded all . . .

A space between the period at the end of the sentence and the beginning of the next would be a plus. :smile:
 
ptonsparky said:
What types of transformers? Do you have 277v lighting?

There were no neutral to EG bonds anywhere on the secondary of these transformers prior to your bonding at the XO of each transfomer? No bonding screws or jumpers at the panels?
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Two 150KVA, one 75KVA Transformer. All lighting is 120. There
were no bonding jumpers from XO to egc at any of transformers,
disconnects,or panels. The only fault path was the case to primary
EGC.The service does have an unbroken 3/0 to CEE and cold water pipe.

This building is the poster child for Poor Electrical Design.

Thanks for the lesson Charlie.
 
From reading your posts, it seems as though there are many grounding issues in this system. If you are opening the service on Saturday just to check for the current on the water pipe, I would wait.

First I would go to all of the panels, and as Don mentioned, I would check for the neutral to equipment ground bonding that may be in place at those locations.
I would also check a few random Jboxes to see what may be lurking there.

Take a good look at 25.30 and see if you can bring those different transformers into compliance with this section number. At that point go back to the cold water pipe and check again for amperage.
Remember, you may not be able to remove all of the amperage on the cold water due to the utility situation.
 
Pierre C Belarge said:
From reading your posts, it seems as though there are many grounding issues in this system. If you are opening the service on Saturday just to check for the current on the water pipe, I would wait.
I'm going to open the main Saturday to install a new breaker.
I'm going to take a reading on the cold water bond and at a few other
locations.Then I'm going to open the main,install the breaker.Then I will be servicing the switch gear,ie.tightening the buss ,checking connections,etc
This install is so bad that I highly doubt the busses have ever seen a
torque wrench.
First I would go to all of the panels, and as Don mentioned, I would check for the neutral to equipment ground bonding that may be in place at those locations.
I would also check a few random Jboxes to see what may be lurking there.
I have opened every panel,transformer,and disconnect in the building.
Except one line conditioner that I found in a small closet.I will check that
tommorrow. I also have been thru at least 15 j-boxes.
Take a good look at 25.30 and see if you can bring those different transformers into compliance with this section number. At that point go back to the cold water pipe and check again for amperage.
Remember, you may not be able to remove all of the amperage on the cold water due to the utility situation.
Click to expand...

I have installed system bonding jumpers in all of the transformers.
All the transformers are compliant with 250.30 now.
I have not opened the gear yet.I'm thinking that if they didn't
install jumpers at the transformers. I bet they didn't install a
bonding jumper in the service. I know for sure they bonded the cold water
unbroken to the CEE and there is a second wire that leaves the CEE
but I cannot say for sure if it bonds to the neutral buss and EGC's.
In order to verify that I will need to open the gear. I cannot open the gear
with it being energized.

What is a "Normal" current level on the GEC or cold water?

Thanks for the replies.
 
Pierre C Belarge said:
I have seen utility documentation that discusses 2 amps as being a number they could live with.
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Thank you for your help Pierre. I have three on the cold water pipe.
Before I bonded the transformers I had 7 on jack chain that wasn't even
supporting a light fixture. I have .75 on a ground wire that feeds a panel
that isn't even energized. This measurement was taken 100' from the nearest
power source.
 
brian john said:
Why dump the main? do zero sequence test, find out is there are downstream grounds. You should be performing iground investigation way before you dump a main IMO.
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I am "Dumping" the main to land a breaker. Since the gear will be
de-energized I'm going to Torque the busses and check for
problems. I do not believe that a torque wrench had been
used in the intial install. I'm going to start a Maintence sched
for this building. I also do not know 100% if the service is bonded
correctly. I don't know what a "iground investigation" is. I am
opening the main to install the breaker because I am not permitted
to bolt this breaker to the buss while it's still energized.

Thank you for your comments.
 
Karl H said:
I am "Dumping" the main to land a breaker. Since the gear will be
de-energized I'm going to Torque the busses and check for
problems. I do not believe that a torque wrench had been
used in the intial install. I'm going to start a Maintence sched
for this building. I also do not know 100% if the service is bonded
correctly. I don't know what a "iground investigation" is. I am
opening the main to install the breaker because I am not permitted
to bolt this breaker to the buss while it's still energized.

Thank you for your comments.
Click to expand...


So if a torque wrench was not utilized during the install, that means all connections are over tightened and re-torquing will not gain anything.

iground was a typing slip "ground investigation" as noted in your other post.

As for installing a CB I am no psychic and could not fore see this.
 
brian john said:
So if a torque wrench was not utilized during the install, that means all connections are over tightened and re-torquing will not gain anything.

iground was a typing slip "ground investigation" as noted in your other post.

As for installing a CB I am no psychic and could not fore see this.[/QU

Ok, I'm done with this. I was just asking for advice from the educated
members of this forum. Thank You ,.for all for your comments. Goodbye.
Click to expand...
 
Karl the thing to realize is that the current may be running INTO the building from poco probs on adjascent buildings. If the objectional current goes away when you dump the main It will be determined to be coming from inhouse. If dumping the main does not fix the situation current could be coming inn from a common point streetside of annother building looking for ground through your good ground. Do not assume anything yet.
 
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