ungrounded system

[apauling]

I am having one of those "i'm sure i understood this" moments. 99 NEC or CEC, single dwelling, meter/main breaker remote from house, ground rod at main breaker, ufer at house, ground and neutral seperate at house. Client is saying that it is an ungrounded system and does not need EGC from main to house. My understanding is that the EGC from main to house is required (non conductive conduit, buried) to protect wire and house panel as there is no real fault path back to main. Client is saying that it is an ungrounded system and that requires no egc. Main and house are 200' away from each other.

What is meant by ungrounded system and is it applicable here? Do not have my code books with me. Client showed me 99 nec reference,ungrounded systems. need both code and explanation for tomorrow, or salt for my humble pie.

thanks in advance

paul

 

[electricman2]

Re: ungrounded system

NEC 250.21 lists systems not required to be grounded. A residential 120/240V service does not fit into this category. It is described in 250.20(B)(1). You are correct in saying an ECG is required to be run with the grounded and ungrounded feeder conductors to provide a fault clearing path.

 

[don_resqcapt19]

Re: ungrounded system

In most cases this installation can be made per the requirements of 250.32(B)(2) and an EGC between the meter/main and the house would not be required. A grounding electrode system and bonding of the neutral would be required at both the metre/main and the house under these conditions.
Don

 

[taylorp]

Re: ungrounded system

Paul: If I understand your description correctly, you ran four conductors from the meter/main breaker (service) to the house? If so then the "ground" wire you ran is the EGC since I understand you ran an insulated neutral also? You are correct than an EGC is required. The code describes what you installed from the meter/main breaker to the house as a "feeder." As far as code references for the '99 code see 250.102 "Equipment Bonding Jumpers" At least this is the way I understand it.

 

[taylorp]

Re: ungrounded system

PS: Don-resqcapt19 is also right if there are no parallel neutral paths between your meter/main breaker (service) and the house. Thanks Don.

 

[apauling]

Re: ungrounded system

thanks guys, i'll make sure I take some salt with me when I look this up in the morning, paul

 

[taylorp]

Re: ungrounded system

Paul: The '99 NEC talks about EGC in articles 215.6, 250.2b, 250.32(b)1, 250.102, 250.118, 250.119, 250.120, 250.134. I don't understand how this client believes that he has an ungrounded system. I never heard of a residence being "an ungrounded system." Must be a Mechanical Engineer.