I was recently asked to look at a review comment that another engineer in our office recieved regarding a design for a building on a university campus. The comment is in regards to grounding at the service entrance. Here is the comment in its entirety:
"There is no equipment bonding jumper shown between the 750kVA transformer and switchboard MSA. An equipment bonding jumper is required per article 250.4A(4). The size of that jumper is dictated per articles 250.30(A)2 and 250.102(C). Because the neutral to ground bond for the system is shown at the switchboard instead of the transformer, it will be required that a ground conductor of appropriate size be run in EACH of the feeders from the transformer to the switchboard."
I contend that ground conductors from the utility transformer to the service entrance equipment are not required and that the service lateral grounded conductor can be bonded to the ground bus and a grounding electrode via properly sized connections and that this is supported by 250.24.A.1 thru 250.24.A.5. I also question the reference to 250.30 as that section refers to separately derived systems and the definition in Article 100 states that a separately derived system is "A premises wiring system whose power is derived from a source of electric energy or equipment, OTHER THAN A SERVICE."
Am I correct or do I need to rethink my thinking?
"There is no equipment bonding jumper shown between the 750kVA transformer and switchboard MSA. An equipment bonding jumper is required per article 250.4A(4). The size of that jumper is dictated per articles 250.30(A)2 and 250.102(C). Because the neutral to ground bond for the system is shown at the switchboard instead of the transformer, it will be required that a ground conductor of appropriate size be run in EACH of the feeders from the transformer to the switchboard."
I contend that ground conductors from the utility transformer to the service entrance equipment are not required and that the service lateral grounded conductor can be bonded to the ground bus and a grounding electrode via properly sized connections and that this is supported by 250.24.A.1 thru 250.24.A.5. I also question the reference to 250.30 as that section refers to separately derived systems and the definition in Article 100 states that a separately derived system is "A premises wiring system whose power is derived from a source of electric energy or equipment, OTHER THAN A SERVICE."
Am I correct or do I need to rethink my thinking?
