Main service fused disconnect

[hhsting]

Attached sketch shows incoming service 200A, 4#3/0 into main fused service disconnect fused at 200A. Load side of the fused service disconnect 4#3/0 feeds the sub Panelboard 200A with main circuit breaker. The sub panelboard has main bonding jumper and service grounding electrode system.


I understand code requires main bonding jumper and grounding electrode system at 200A main fused service disconnect but its at sub panelboard. The fused disconnect does Not have equipment grounding conductor load side and the fused disco does not have main bonding jumper

Questions:

1. Fuses do not require equipment grounding conductor to operate correct so engineering wise what is attached should be ok correct?


2. Can the fused disco metallic enclosure be bonded thru neutral and not have objectionable current? Or it needs to have EGC? Speaking only Engineering wise

 

[MyCleveland]

Add the service meter to your sketch and try rewording question 1.

 

[hhsting]

Add the service meter to your sketch and try rewording question 1.

Utility meter is ahead of main service fused disconnect. See attached sketch. I dont get it fuses don’t require EGC to operate ir do they require it? Thats question no. 1

 

[electrofelon]

Add the service meter to your sketch and try rewording question 1.

Agree. Also the type of occupancy We need to know if the fused disco can be considered a meter disconnect or an emergency disconnect.

 

[hhsting]

Agree. Also the type of occupancy We need to know if the fused disco can be considered a meter disconnect or an emergency disconnect.

Occupancy is non dwelling unit, commercial restaurant under NEC 2017 code, 208/120V three phase. See post #3 for revised sketch. It is Not a meter disconnect and it is Not emergency disco. Its main fused service disconnect.

 

[infinity]

Use the fused disconnect as the service disconnect, 4 wire feeder to MCB, GEC to fused disco. No MBJ at CB.

 

[hhsting]

Use the fused disconnect as the service disconnect, 4 wire feeder to MCB, GEC to fused disco. No MBJ at CB.

I know that is the “usual” way. However what is shown in post #3 sketch work and function in equivalent manner and provide equivalent safety as the “usual” way or not?

 

[augie47]

Just beacuse it works does not mean it complies with the Code; To meet NEC, follow Post #6

 

[MyCleveland]

You need to get MHs books on art 250 or a copy of Soares and spend a few weekends on the entire section…embrace it and your reviews will flow much faster.

 

[hhsting]

You need to get MHs books on art 250 or a copy of Soares and spend a few weekends on the entire section…embrace it and your reviews will flow much faster.

I know the “code” way. It was approved “code” way. plans went to field and contractor altered it in field and inspector said to go back to plan review for approval.

So what is built as shown on post #3.

So then the question is Not asking for code way is it. Its asking if post #3 attachment would function and work equivalent as the code way or not?

 

[don_resqcapt19]

I know the “code” way. It was approved “code” way. plans went to field and contractor altered it in field and inspector said to go back to plan review for approval.

So what is built as shown on post #3.

So then the question is Not asking for code way is it. Its asking if post #3 attachment would function and work equivalent as the code way or not?

Like lots of other non-code complaint installations, it will work just fine.

As far as objectionable current, if there raceway is non-metallic between the outside disconnect and the inside panel there won't be any.

However, you say it is going back to plan review for approval of a non-compliant installation. The only way that it can be approved is by the written special permission provided for in 90.4. I can't imagine any code enforcement authority providing such written permission for a code violation.

 

[LarryFine]

Its asking if post #3 attachment would function and work equivalent as the code way or not?

Yes,, it will function. That may not get you through planning, though. Let us know your results.

 

[hhsting]

Like lots of other non-code complaint installations, it will work just fine.

As far as objectionable current, if there raceway is non-metallic between the outside disconnect and the inside panel there won't be any.

However, you say it is going back to plan review for approval of a non-compliant installation. The only way that it can be approved is by the written special permission provided for in 90.4. I can't imagine any code enforcement authority providing such written permission for a code violation.

Not everything requires to be exactly per code. If it works and provides equivalent safety and plans are approved so then it can be just as safe? By the way how is metallic conduit product objectionable current?

 

[electrofelon]

Not everything requires to be exactly per code. If it works and provides equivalent safety.

Does your state law on adopted codes say that??

 

[LarryFine]

Not everything requires to be exactly per code. If it works and provides equivalent safety and plans are approved so then it can be just as safe? By the way how is metallic conduit product objectionable current?

By not having the intended isolated neutral past the service OCPD, a metallic conduit (or bare neutral like in SE cable) would carry neutral current.

While that's accepted and allowed ahead of the service, it's undesirable past it because of the concern of voltages-to-earth on bonded surfaces.

Added: The neutral/EGC/GEC/MBJ junction is considered to be the "ground reference" in the system. Separate grounds and neutrals keeps the EGC as close to zero volts as possible.

 

[MyCleveland]

Not everything requires to be exactly per code. If it works and provides equivalent safety and plans are approved so then it can be just as safe? By the way how is metallic conduit product objectionable current?

What!! Are you starting now to pick and choose ?

You have another problem, have you considered what the plan author will say ?

 

[wyreman]

Yeah I agree, conformity to the code is necessary simply because otherwise each installation becomes a soup and if every installation becomes some kind of discovery, society wouldn't be able to get much done. But I also find plenty of special circumstances like you where you see if you can reduce unnecessary hardship

A better drawing might had led to more credence to this being a well considered objection.
Also, why did the contractor field modify it? That seems to be the origin of the problem which is glossed over.

Plan review is meant to review plans for conformity to established safety, not to "wing it" and pronounce themselves equal to code making board.

Why did builder field modify? or even accept the approved plans knowing he would face the inspector?

I remember I was there to witness the torquing down of main Bellingham washers and the contractor stripped the threads on some 1600a main- he tried to shine it on altho we could all see the wrench spinning empty

 

[hhsting]

By not having the intended isolated neutral past the service OCPD, a metallic conduit (or bare neutral like in SE cable) would carry neutral current.

While that's accepted and allowed ahead of the service, it's undesirable past it because of the concern of voltages-to-earth on bonded surfaces.

Added: The neutral/EGC/GEC/MBJ junction is considered to be the "ground reference" in the system. Separate grounds and neutrals keeps the EGC as close to zero volts as possible.

Well would not the ground junction reference also keep the neutral close to zero volts Not only EGC? After all they are all tied together in ground junction. So on the line side between the main service fused disconnect and sub panel where their is no EGC but their is neutral and metallic conduit how exactly would over voltage from earth happen on bonded surface? For X amount of distance line side of neutral must be close to zero volts no?

 

[hhsting]

Does your state law on adopted codes say that??

Thats what a written permission is. Its in NEC??

 

[wyreman]

90.4

when I was little I had to rip out a supplemental ground rod at a remote loadcenter that was just bonded to the ground bus only.
what's wrong with that? "parallel paths for the ground fault current" ... meh
but isn't another rod required at xfmr, outbuildings and hot tubs?
and who cares about a rod anyway - its the water that counts

I thought it was unreasonable and read soares cover to cover
abandoned the supplemental ground anyways
I had driven it by hand!

pick your battles