Sizing water bond

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ppsh

Member
Location
CA
Occupation
Electrician
Have a 600a service set by the road, poco is incoming parallel 350 triplex form the padmount to meter main. 400a breaker in the distribution section feeds a house ~500ft away. The 400a run to the house is triple paralleled 600kcmil AL for voltage drop. Run converts at each end down to double paralleled 250kcmil AL for 15 feet or so to be able to land it in the gear.

Following table 250.66, I would need a 250Al water bond coming from the 400a panel at the house if I'm calculating it based off of the triple 600s with its 1800kcmil equivalent. Am I able to use the combined area of the 250s instead? 1/0AL would be a lot more reasonable. Seems ridiculous connecting a 250kcmil bond to 3/4" type M copper.

Only the interior piping is copper so not a GEC.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Look at 250.104(A). The correct table is 250.102(C)(1) which is based on the "Size of Largest Ungrounded Conductor or Equivalent Area for Parallel Conductors". Since you have two different sizes you would base the bonding jumper on the larger of the two.
 
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