Service conductors

[electrofelon]

Thats a big problem. One can use 2000 kcmil Al 8 sets and get MBJ of 2000 kcmil

That would only take 6 sets of 2000 AL and require a 1500 MBJ

 

[hhsting]

That would only take 6 sets of 2000 AL and require a 1500 MBJ

Right based on load to be served which would be 3200A Not 4000A. However max load to be served would be 4000A so why not size on that?

 

[electrofelon]

Right based on load to be served which would be 3200A Not 4000A. However max load to be served would be 4000A so why not size on that?

You have typos and inconsistencies with your numbers in here as well as the OP, but going off the assumption that the load is 3200 A, you go off that because that is what the code says to use.

 

[hhsting]

You have typos and inconsistencies with your numbers in here as well as the OP, but going off the assumption that the load is 3200 A, you go off that because that is what the code says to use.

So who choses cable size the designer, whats already at the site 500kcmil Al?. I wish there was some guidance on that in code

 

[electrofelon]

Are you sure MBJ is wire type? Seems unlikely to me. IF so is it factory installed? Code isnt really perfectly clear, but I think most would agree if its factory installed you dont have to worry about it.

 

[electrofelon]

So who choses cable size the designer, whats already at the site 500kcmil Al?. I wish there was some guidance on that in code

Unless someone has other ideas or different reading of that section, I would just choose whatever seems like the most likely combination. Perhaps you could go off the number of termination provisions provided.

 

[hhsting]

Unless someone has other ideas or different reading of that section, I would just choose whatever seems like the most likely combination. Perhaps you could go off the number of termination provisions provided.

In 4000A fused disconnect what would that be?

 

[electrofelon]

In 4000A fused disconnect what would that be?

I am not sure off hand. Someone else should now who does stuff of that size more often.

FYI, there isnt such thing as a "4000A fused disconnect". Technically it would be a "bolted pressure switch" above 1200 Amps.

 

[hhsting]

I am not sure off hand. Someone else should now who does stuff of that size more often.

FYI, there isnt such thing as a "4000A fused disconnect". Technically it would be a "bolted pressure switch" above 1200 Amps.

Would bolted pressure switch have bus as MBJ?

 

[hhsting]

Are you sure MBJ is wire type? Seems unlikely to me. IF so is it factory installed? Code isnt really perfectly clear, but I think most would agree if its factory installed you dont have to worry about it.

Designer said wire but have to double check with him again

 

[augie47]

Would bolted pressure switch have bus as MBJ?

If it's service rated, never seen one that didn't.

 

[electrofelon]

Designer said wire but have to double check with him again

As I and others have said, skeptical that such large equipment would have a field installed wire MBJ.

I admit to installing a wire MBJ in some 800-1200A Siemens panelboards because I can never figure out where the MBJ bar they supply goes

 

[hhsting]

As I and others have said, skeptical that such large equipment would have a field installed wire MBJ.

I admit to installing a wire MBJ in some 800-1200A Siemens panelboards because I can never figure out where the MBJ bar they supply goes

Confirmed it has field installed wire MBJ