Sizing a Bonding Conductor

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P.E.S.

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I need help to size a water/gas bonding conductor on a 600 a service. There are no feeder conductors for me to know the size. Inspector calling for
#3/0cu, that seeems too big, but cannot find specifically in code to refute or agree with his call. Thanks!
 
P.E.S. said:
I need help to size a water/gas bonding conductor on a 600 a service. There are no feeder conductors for me to know the size. Inspector calling for
#3/0cu, that seeems too big, but cannot find specifically in code to refute or agree with his call. Thanks!
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Please explain how there are no conductors?:confused:
 
iwire said:
Please explain how there are no conductors?:confused:
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I contacted Power company, to see what size feeders they were going to pull to new 600a service. going to pull parallel 350kcmil. Inspector said cannot go on size of feeders because they are not installed yet. Hope that helped clarify. Thanks
 
I contacted the Power company, said they were going to pull parallel 350kcmil alu.feeders. Inspector said cannot go of this size because they are not pulled yet, must size acording to 250.66 table notice note #2. hope this helps thanks
 
P.E.S. said:
Inspector calling for #3/0cu, that seeems too big, but cannot find specifically in code to refute or agree with his call. Thanks!
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You can't go wrong with 3/0 Cu here :wink: ...although it *may* be possible to use 1/0 Cu.


Unless you can show the inspector the load calc's to justify Note #2 to T250.66, looks like you're stuck with the 3/0 Cu.
 
On a 600 amp service it's almost certain to be at least a 2/0.
But, some of your terminology confuses me.
Normally, what POCO does has nothing to do with your GEC size.
Their supply would probably be a "service drop" or "service lateral" not a "feeder"
The conductors to the breaker, which are almost always contractor installed, would be "service entrance" conductors and those would be the determining factor. At 600 amp thats often (2) 350kmcil for a 700 kcmil totaol which would call for a 2/0 GEC
 
P.E.S. said:
I need help to size a water/gas bonding conductor on a 600 a service. There are no feeder conductors for me to know the size. Inspector calling for
#3/0cu, that seeems too big, but cannot find specifically in code to refute or agree with his call. Thanks!
Click to expand...

Look at 250.66 for the grounding electrode but to a gas line, unless it is CSST, you may not need to bond it. If you have a gas furnace or gas range then the gas line is bonded thru the EGC of the circuit feeding it. Not the same for a water line. Art. 250.104 (B)
 
If you have 3 sets of 3/0 copper from the meter to the panel or panels then a 1/0 is needed.

Since I have never seen a combo meter panel at 600 amps I would guess you probably have either 3 200 amp panels feed from the service or you have a larger 1200 MCM cable. In the latter case you need 3/0. I think this is what Celtic was getting at.
 
P.E.S. said:
I need help to size a water/gas bonding conductor on a 600 a service. There are no feeder conductors for me to know the size. Inspector calling for
#3/0cu, that seeems too big, but cannot find specifically in code to refute or agree with his call. Thanks!
Click to expand...

Note 2 states that where there are not any service conductors........

2. Where there are no service-entrance conductors, the grounding electrode conductor size shall be determined by the equivalent size of the largest service-entrance conductor required for the load to be served.

Rick
 
Sizing a Bonding Conductor

I had a similar situation last week. However, the service entrance conductors were present at 350 kcmil AL (which the local electrical provider pulled). So I sized the GEC for the water pipe(had 10' or more copper in the earth) using Table 250.66. Which would equal a #2 Cu. However the inspector stated that he does not look at what is pulled into the service entrance because it is a service lateral (even though wire was present!). Therefore i must size the GEC to 250.66 Note #2, which would make me size the GEC wire to the rating of the load to be served, which was a 400 amp breaker. Sending me to Table 310-16 to find the wire size of 600kcmil cu at 75 degrees, putting me back to Table 250.66 looking at now running a 1/0 cu. An other views on this? I had a hard time understanding why? :-?
 
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