Two switchboards

[Wire-Smith]

I wish I would have known about that article 70 posts ago and just referenced to that, LOL. Thanks

It also makes me think I might not be alone on mars on this subject either

 

[hhsting]

You never replied to my question about my other two suggestions, what do you think about those? The one is just pulling extra wire with service and adding surge protectors and getting permission from AHJ

You mean the one about utility xfmr bonding? How does that work?

Sent from my SM-G935U using Tapatalk

 

[Wire-Smith]

You mean the one about utility xfmr bonding? How does that work?

Sent from my SM-G935U using Tapatalk

Your only neutral to ground bonds would be at transformer, you would pull an additional wire(supply side bonding jumper) with the services. And I would add surge protection at the premises service equipment because grounding the neutral at the premises served as that.

 

[Wire-Smith]

It's arbiterially not code compliant so you need AHJ approval. NEC 90.4 "special permission"

 

[hhsting]

It's arbiterially not code compliant so you need AHJ approval.

I am not the designer for this project. Funny thing is my area their is soo much work that AHJ contracts out work otherwise they fall behind. For this project I am contractor for AHJ plans reviewer.

I am lets say 95% sure approval may not be granted.

Sent from my SM-G935U using Tapatalk

 

[Wire-Smith]

It arbiterially violates 250.24(b), but if that xfmr was premises owned it would be code compliant, er'go arbitrary and 90.4

 

[Wire-Smith]

I see, now your conversation direction makes more sense. I know what I think most would do in your situation which is allow it and I won't beat up on anyone that would. But you can probably guess what a Martian like myself would do.

 

[hhsting]

I see, now your conversation direction makes more sense. I know what I think most would do in your situation which is allow it and I won't beat up on anyone that would. But you can probably guess what a Martian like myself would do.

What you said earlier has happened once around here different project not by me as contractor to the AHJ I know. So yes I would be prone to stop it before it happens again but their is not much I can do besides enforce what NEC says. AHJ has no local code to enforce it.

Sent from my SM-G935U using Tapatalk

 

[Wire-Smith]

What you said earlier has happened once around here different project not by me as contractor to the AHJ I know. So yes I would be prone to stop it before it happens again but their is not much I can do besides enforce what NEC says. AHJ has no local code to enforce it.

Sent from my SM-G935U using Tapatalk

I would say if you wanted to you could argue a conservative view of a reasonable expectation of objectionable current with the proposed design. Violation of NEC

 

[hhsting]

I would say if you wanted to you could argue a conservative view of a reasonable expectation of objectionable current with the proposed design. Violation of NEC

Ok but location of FP swbd would still be the same and so would the exterior swbd. Only thing that would change is one service with line side tap from exterior swbd separate enclosure.

Our local code now says they would need emergency generator as backup if tapped ahead service disco within swbd enclosure.

Would all that still prevent objectionable current?

Sent from my SM-G935U using Tapatalk

 

[Wire-Smith]

Ok but location of FP swbd would still be the same and so would the exterior swbd. Only thing that would change is one service with line side tap from exterior swbd separate enclosure.

Our local code now says they would need emergency generator as backup if tapped ahead service disco within swbd enclosure.

Would all that still prevent objectionable current?

Sent from my SM-G935U using Tapatalk

If AHJ would only require a main bond at the first swbd , and have an EGC TO FP swbd and no main bond there

 

[hhsting]

If AHJ would only require a main bond at the first swbd , and have an EGC TO FP swbd and no main bond there

Since tapped from line side from the enclosure of exterior swbd, FP swbd still is fed from incoming service conductors. So FP swbd main breaker would still be main service disconnect and require neutral to bond.

Sent from my SM-G935U using Tapatalk

 

[Wire-Smith]

I hate to throw another wrench. But something often overlooked is if generator has neutral and ground bonded then the transfer switch should also switch the neutral.

 

[Wire-Smith]

Since tapped from line side from the enclosure of exterior swbd, FP swbd still is fed from incoming service conductors. So FP swbd main breaker would still be main service disconnect and require neutral to bond.

Sent from my SM-G935U using Tapatalk

Then you would have two main bonds from the same electrical system on the same premises, so the only change is you eliminate the problem I described with losing a service neutral but the other objectionable current issues, if any are no further mitigated

 

[Wire-Smith]

I think you could allow only bonding at the first switchboard in your New scenario

 

[hhsting]

Then you would have two main bonds from the same electrical system on the same premises, so the only change is you eliminate the problem I described with losing a service neutral but the other objectionable current issues, if any are no further mitigated

Yes problem of objectionable current remains.

I can have the designer write note on plans that after installation complete have contractor verify installation complies per NEC 2014 Article 250.6 and to correct any objectionable current.

However not sure to what extent contractors would do this in field.

Sent from my SM-G935U using Tapatalk

 

[Wire-Smith]

What problem do you see with only bonding at utility transformer?

 

[hhsting]

What problem do you see with only bonding at utility transformer?

Nec 2014 250.28 requires bonding at service disco. If you bond at utility xfmr regardless per NEC 2014 Article 250.28 you would rebond at service disconnects.

Sent from my SM-G935U using Tapatalk

 

[hhsting]

Nec 2014 250.28 requires bonding at service disco. Utility xfmr is not service disconnect. If you bond at utility xfmr regardless per NEC 2014 Article 250.24(B) you would still be required rebond at service disconnects.

Sent from my SM-G935U using Tapatalk

Sent from my SM-G935U using Tapatalk

 

[Wire-Smith]

Nec 2014 250.28 requires bonding at service disco. If you bond at utility xfmr regardless per NEC 2014 Article 250.28 you would rebond at service disconnects.

Sent from my SM-G935U using Tapatalk

That's an arbitrary view of those requirements
If xfmr was premises owned your clearly allowed to only bond at transformer.
The main bond location being required at two locations when the tap originated in an enclosure with a main bond is a ridiculously arbitrary interpretation. Electricity doesn't care what you call a service disconnect.