What size

[hhsting]

Please see attach sketch shows ct cabinet with service wire trough.. From the CT cabinet to wire trough have the following:

1. 600kcmil neutral to neutral bar in first service disco

2. 3 sets of 300kcmil neutral to neutral bar in second service disco

3. 3 sets of 300kcmil neutral to neutral bar in third service disco

From the service disco I have the following:

1. Neutral bar from first service disco to terminal bar in wireway #1/0 awg

2. Neutral bar from second service disco to terminal bar in wireway #3/0 awg

3. Neutral bar from third service disco to terminal bar in wireway #3/0 awg

The terminal bar connects to building steel, water pipe each with grounding electrode conductors

The question is wireway must be bonded by neutral NEC 2017 section 250.80 so bonding jumper from terminal bar to the wire way is provided. What size should that bonding jumper be? I am thinking 500kcmil? Yes no? If no then what size?

 

[Joe.B]

Supply side bonding jumper sized per table 250.102(C)(1), if only one bonding jumper then sized for aggregate of all ungrounded conductors?
Load side equipment bonding jumper sized per 250.122, sized for the largest OCPD device supplying circuits?

Hopefully the pros will confirm, or correct me if I'm mistaken.

 

[infinity]

What size conductors are on the line side of the CT cabinet?

 

[hhsting]

What size conductors are on the line side of the CT cabinet?

That is not known and they are existing. What you have in mind?

 

[infinity]

That is not known and they are existing. What you have in mind?

The wireway is on the line side of the service disconnects so I'm thinking that the service conductors feeding the CT cabinet would be used to determine the bonding jumper size.

 

[hhsting]

The wireway is on the line side of the service disconnects so I'm thinking that the service conductors feeding the CT cabinet would be used to determine the bonding jumper size.

Ok but i dont have that info

The 3/0 awg are supply side bonding jumper and so is 1/0 awg in sketch from service disco to terminal bar from each individual neutral in the service disco.

Imagine where the 3/0awg terminates on terminal bar at that point I place 3/0 awg bonding jumper to wire way. Same would be for 1/0 awg except place 1/0 awg and same another 3/0 awg except place 3/0 awg


Essentially those 3/0awgs and 1/0 awgs are in parallel from terminal bar to wire way


From what I have can I add area of all the supply side bonding jumper from service disco to the terminal bar: 3/0 awg + 3/0 awg + 1/0 awg say equals Y. So then Y would be my bonding jumper size from terminal bar to the wire way and would code allow this or not?

 

[don_resqcapt19]

Ok but i dont have that info

The 3/0 awg are supply side bonding jumper and so is 1/0 awg in sketch from service disco to terminal bar from each individual neutral in the service disco.

Imagine where the 3/0awg terminates on terminal bar at that point I place 3/0 awg bonding jumper to wire way. Same would be for 1/0 awg except place 1/0 awg and same another 3/0 awg except place 3/0 awg


Essentially those 3/0awgs and 1/0 awgs are in parallel from terminal bar to wire way


From what I have can I add area of all the supply side bonding jumper from service disco to the terminal bar: 3/0 awg + 3/0 awg + 1/0 awg say equals Y. So then Y would be my bonding jumper size from terminal bar to the wire way and would code allow this or not?

Then you cannot answer the question of what size bonding jumper is required, because that size of the bonding jumper is based ONLY on the side of the ungrounded service conductors.

 

[augie47]

The key is back to infinity's question on service conductors but...
out of curiosity is that (1) 600 per phase on the 1st disconect and (3) 300s per phase on the others ??

 

[jim dungar]

Ok but i dont have that info

From what I have can I add area of all the supply side bonding jumper from service disco to the terminal bar: 3/0 awg + 3/0 awg + 1/0 awg say equals Y. So then Y would be my bonding jumper size from terminal bar to the wire way and would code allow this or not?

Are you designing this or are you passing judgement on someone else's design.

 

[hhsting]

Are you designing this or are you passing judgement on someone else's design.

I am Not designing it just seeing what the size would be per nec. Someone else designed it

 

[hhsting]

The key is back to infinity's question on service conductors but...
out of curiosity is that (1) 600 per phase on the 1st disconect and (3) 300s per phase on the others ??

Yes thats (1) 600 per phase on the 1st disconnect and (3) 300s per phase on other two

 

[infinity]

As I mentioned earlier and as Don and Augie have pointed out you need to figure out what is feeding the CT cabinet to size the wireway bonding jumper.

 

[augie47]

Did the original design show a bond jumper to the wireway?
(There are other means by which the wireway would be bonded)

 

[electrofelon]

Did the original design show a bond jumper to the wireway?
(There are other means by which the wireway would be bonded)

That's what I am thinking is there is not enough information to answer. I see the things everyone is calling bonding jumpers as GEC taps to a GEC busbar. The wireway MAY be properly bonded by the raceway to the CT cabinet or the raceways to the service disconnects (one would need "service bonding" on each side of the raceways).

 

[hhsting]

Did the original design show a bond jumper to the wireway?
(There are other means by which the wireway would be bonded)

Yes

 

[augie47]

There are so many different issues that arise from following the sketch as drawn that I can't imagine it actually being installed that way in the field but, if we base the number on only the conductors shown (not the proper way as others have pointed out) it would be 12=1/2% of 2,400kcmil or a 300 kcmil jumper.

 

[hhsting]

There are so many different issues that arise from following the sketch as drawn that I can't imagine it actually being installed that way in the field but, if we base the number on only the conductors shown (not the proper way as others have pointed out) it would be 12=1/2% of 2,400kcmil or a 300 kcmil jumper.

What other issues you are talking about?

 

[augie47]

What other issues you are talking about?

That's getting into installation details and specifics related to this one install (some of which we don't know such as the size of the actual service lateral, type of conduit used, methods of bonding, etc. An experienced contractor and knowledgeable inspector will, work all that out in the field. What is actually in the field may have little resemblance to what you have drawn on a piece of paper.
We answered your original question on jumper size (event then based on inadequate data). To go further would be a waste of time.

 

[hhsting]

That's getting into installation details and specifics related to this one install (some of which we don't know such as the size of the actual service lateral, type of conduit used, methods of bonding, etc. An experienced contractor and knowledgeable inspector will, work all that out in the field. What is actually in the field may have little resemblance to what you have drawn on a piece of paper.
We answered your original question on jumper size (event then based on inadequate data). To go further would be a waste of time.

Ok thanks


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[electrofelon]

Ok thanks


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A suggestion:. I understand that if you haven't been an electrician, it's not as easy for you to spot something that is likely to change or that has a zillion different ways it could be installed in the fileld.. but this is one of those things and maybe just provide a general note on the plans saying something like "bonding jumper size and arrangement to be verified at inspection.".