Cold water bond

Jgoot

Member
Location
San Jose, Ca
Occupation
Inside wireman
Hello all,

Ive searched the forum, and the internet and still can't come to a conclusion.

Usually engineers do this stuff for our jobs, but I thought I would try and figure it out, until the newest 250.66 stumped me.

Commercial building 4000A 3phase 480v main. The building was built in 1996, and we are doing a full gut and TI. Main switch board is energized so I havent opened the utility or main section to see if there are feeder cables (for sizing). Buss duct is used from the utility transformer into the building and into the back of the main.

The issue: the cold water bond is made in the core of the building at a restroom using 3/0 copper to 2" copper plumbing, unfortunately the water service (3" copper) enters the building about 150 feet away and completely on the opposite side of the building as the electric service (estimated 300'). I need to relocate this water bond to be with in 5' of the service entrance right? I initially thought I could run a 3/0 cu conductor, but a check of 250.66 now has "notes" for 1100kcmil or larger. These notes read like lawyer speak.

Can someone help me size my water bond? Code reference, and explanation? Or help me justify why I dont need to move it?

Thank you in advance,
Josh
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Your conductors are larger than 1100 kcmil so the largest GEC required by table 250.66 is #3/0.

Welcome to the forum.
 

Jgoot

Member
Location
San Jose, Ca
Occupation
Inside wireman
Perfect, thank you for the quick response!

I often search this forum to help me solve my field issues. Its a great resource!

Thanks again,
Josh
 

Electromatic

Senior Member
Location
Virginia
I was about to make the clarification Larry just did.
Also, you can use the building steel as a jumper to get to that location of the water pipe.
 

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
Can someone help me size my water bond? Code reference, and explanation? Or help me justify why I dont need to move it?

Thank you in advance,
Josh
You keep saying "water bond", are you actually talking about bonding the water piping or using it as a GEC. If you are in fact talking about bonding per 250.104 you will not have to move it, if it is a GEC then it could (and probably will be) a problem. Can you tell us which situation you are asking about?

Also if you talking about a GEC make sure the water service meets the conditions of 250.52(A)(1), I have seen commercial buildings supplied by non metallic piping.

Roger
 

Jgoot

Member
Location
San Jose, Ca
Occupation
Inside wireman
Multiple replys, I love it.

@ Larry - Yes, with in 5' of the water service entrance, not electrical service.

@ Roger - I dont think there is an intent to use the water service as and GEC. The underground domestic water piping here is usually not metallic until it hits the meter and or back flow device, then transitions to copper and enters the building. Our drawings usually indicate a 3/0 GEC to cold water piping with in 5' of the service entrance (water service). This job does not have that detail. I am essentially trying to get work done while in the demo portion of the job, due to the ridiculous schedule these jobs are given, and the drawings do not have the detail I usually refer to. If I ask an engineer they will probably cut and paste the detail into the drawings 3-4 weeks from now. This specific AHJ tends to pick appart things like this and I would prefer to do it now, even if its not needed rather than do it later when there are walls and just under 1 million dollars in lighting I'm worried about damaging. Yes, 1 million. Im not worried about spending money on 400' of 3/0, its change in this budget.

I tried to attach a generic bonding detail that is usually on our drawings, but couldn't figure out how. Guess its irrelevant anyway.

Josh
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Multiple replys, I love it.

@ Larry - Yes, with in 5' of the water service entrance, not electrical service.

@ Roger - I dont think there is an intent to use the water service as and GEC. The underground domestic water piping here is usually not metallic until it hits the meter and or back flow device, then transitions to copper and enters the building. Our drawings usually indicate a 3/0 GEC to cold water piping with in 5' of the service entrance (water service). This job does not have that detail. I am essentially trying to get work done while in the demo portion of the job, due to the ridiculous schedule these jobs are given, and the drawings do not have the detail I usually refer to. If I ask an engineer they will probably cut and paste the detail into the drawings 3-4 weeks from now. This specific AHJ tends to pick appart things like this and I would prefer to do it now, even if its not needed rather than do it later when there are walls and just under 1 million dollars in lighting I'm worried about damaging. Yes, 1 million. Im not worried about spending money on 400' of 3/0, its change in this budget.

I tried to attach a generic bonding detail that is usually on our drawings, but couldn't figure out how. Guess its irrelevant anyway.

Josh
That could just be a boiler plate specification because if there is no metallic water pipe buried for at least 10' in the earth there is no electrode and the bonding connection does not need to be within 5'.
 
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