Main bonding jumper Question

[Pullnwire]

I apologize in advance for what may be a question with an obvious answer. I am installing a new 2000 amp 120/208 3phase 4 wire service at a machine shop to upgrade the existing service. I just got my plan check corrections back from the city, and he wants me to show the main bonding jumper on the single line. He said I need to size my jumper per 250.66 12.5% of my service conductors puts me at a 400KCMIL bonding jumper.

Call me crazy, but I thought the main bonding jumper came pre-installed in the new service near the main breaker? I've been sifting through his notes all day, and it just doesn't make sense. Why is he asking me to size one, if the factory supplies one listed for the service size?

 

[augie47]

It has been experience, if the gear is ordered and supplied as "Suitable for Service", the bonding jumper will be installed or supplied.

 

[texie]

I apologize in advance for what may be a question with an obvious answer. I am installing a new 2000 amp 120/208 3phase 4 wire service at a machine shop to upgrade the existing service. I just got my plan check corrections back from the city, and he wants me to show the main bonding jumper on the single line. He said I need to size my jumper per 250.66 12.5% of my service conductors puts me at a 400KCMIL bonding jumper.

Call me crazy, but I thought the main bonding jumper came pre-installed in the new service near the main breaker? I've been sifting through his notes all day, and it just doesn't make sense. Why is he asking me to size one, if the factory supplies one listed for the service size?

It seems a little odd to call that out specifically. Like you say, service rated gear of that size will already have it and it will be a bus bar piece not a wire type.

 

[Smart $]

I agree with you and others... but I believe the main point is to show it on the one-line. IMO you just show it and annotate as appropriate for the installation, which will not necessarily be as suggested by plan reviewer.

 

[Pullnwire]

Many thanks!

Many thanks!

Thanks guys! Ive worked so hard on getting this job, and it seems like I have been staring and line drawings and panel schedules for the last few days trying to sort this out. I guess I needed a fresh set of brains.

 

[texie]

Thanks guys! Ive worked so hard on getting this job, and it seems like I have been staring and line drawings and panel schedules for the last few days trying to sort this out. I guess I needed a fresh set of brains.

Maybe he is just cover all the bases and thinks you may somehow lose the factory bus bar and you will have to replace it with a wire type jumper and then you will know how to size it.:lol: