Separately derived system

[hhsting]

I have transformer 75kva in building tenant space which has grounding electrode conductor to building grounding electrode system per NEC 2017 section 250.30(A)(4). The building grounding electrode system already has bonded building steel and underground water pipe.

However their is still one bonding jumper provided from xfmr to the steel and another second from xfmr to water pipe.

I see NEC 2017 section 250.104(C)(2) exception number 1 and 2 these two additional bonding jumpers from xfmr to steel and water pipe are not required. Would I be correct or incorrect about this?

 

[hhsting]

I have transformer 75kva in building tenant space which has grounding electrode conductor to building grounding electrode system per NEC 2017 section 250.30(A)(4). The building grounding electrode system already has bonded building steel and underground water pipe.

However their is still one bonding jumper provided from xfmr to the steel and another second from xfmr to water pipe.

I see NEC 2017 section 250.104(C)(2) exception number 1 and 2 these two additional bonding jumpers from xfmr to steel and water pipe are not required. Would I be correct or incorrect about this?

No one has any opinions?


Sent from my iPhone using Tapatalk

 

[tom baker]

You need to bond to the water pipe in the area served,

 

[hhsting]

You need to bond to the water pipe in the area served,

Would not NEC 2017 section 250.104(D)(1) exception no. 1 apply?

 

[don_resqcapt19]

The exceptions do not apply because you are not using the water pipe or the building steel as the grounding electrodes fro the separately derived system. You are connected to those via the building grounding electrode system. The rule requires a connection from the SDS to the steel and water pipe in the area served by the SDS.

 

[petersonra]

What does "in the area" mean?

 

[hhsting]

The exceptions do not apply because you are not using the water pipe or the building steel as the grounding electrodes fro the separately derived system. You are connected to those via the building grounding electrode system. The rule requires a connection from the SDS to the steel and water pipe in the area served by the SDS.

Lets say I bring conductor from xfmr to the building steel which is part of grounding electrode system which is same as saying conductor from xfmr to grounding electrode system. I dont see how the exceptions dont apply?

 

[don_resqcapt19]

Lets say I bring conductor from xfmr to the building steel which is part of grounding electrode system which is same as saying conductor from xfmr to grounding electrode system. I dont see how the exceptions dont apply?

The rule is clear that you need to make a bond in the area served by the SDS.

You seem to have already decided what answer you will accept, so why bother asking the question?

 

[don_resqcapt19]

What does "in the area" mean?

Only your AHJ knows, but it says "area served", so in a location where the circuits get their power from that SDS.

 

[hhsting]

The rule is clear that you need to make a bond in the area served by the SDS.

You seem to have already decided what answer you will accept, so why bother asking the question?

I am trying to understand the rule. I am kinda of confused. Nec 2017 section 250.30(A)(4) grounding electrodes was amended to say to use building grounding electrode system as grounding electrode for separately derived system.

So each separately dervied system would have to go to building grounding electrode system.

I dont know where one can even apply the exceptions bldg steel as grounding electrode or water pipe as grounding electrode for separately derived system since grounding electrode section 250.30(A)(4) says go to building grounding electrode system for separately derived system. The exceptions would never apply?? Why even have these exceptions then?