Nec 250.102(c)

[erickench]

The last part of the above NEC section states the following:

Where the service entrance conductors are paralleled in two or more raceways or cables, the equipment bonding jumper, where routed with the raceways or cables, shall be run in parallel. The size of the bonding jumper for each raceway or cable shall be based on the size of the service-entrance conductors in each raceway or cable.

The last sentence says:"based on the size of the service-entrance conductors in each raceway or cable" and not the sum of the size of each raceway or cable. What is the correct interpretation of this rule? Some people think it's based on the sum.

 

[cpal]

It may be done either way One bonding jumper sized from 250.66 or 12-1/2% of the sum (dasey chained) or a jumper from each raceway to the Grounded buss. see Soares Book on Grounding and Bonding IAEI 2008 pages 83-86.

 

[infinity]

The last sentence says:"based on the size of the service-entrance conductors in each raceway or cable" and not the sum of the size of each raceway or cable. What is the correct interpretation of this rule? Some people think it's based on the sum.

It's not based on the sum. The same rule would apply for parallel conductors on a transformer secondary. Each raceways' EGC would be based on the size of the conductors within the raceway not all of the parallel sets added together.

 

[erickench]

Yes that is what the code reads.