meterbank - 1600A incoming with 1200A horizontal bus on each side of main

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jjs

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If I have a 1600A main cb incoming section for a meterbank that has meter modules on both the left and the right, each meter module section only has 1200A horizontal bus, is this allowed per NEC? Assuming the left side does not exceed 1200A and the right side does not exceed 1200A and the combination does not exceed 1600A.

My eaton rep says this is allowed per NEC but that the city of chicago does not allow it.
Any ideas which code section would govern this?

Thanks for your help.
 
I couldn't tell you, but I do know the Siemens 3000 amp gear I was just installing has two breaker distribution sections. One had 1600 amp vertical buss, the other 1200 amp.

I don't expect any issues with inspection or with it under load.
 
jjs said:
If I have a 1600A main cb incoming section for a meterbank that has meter modules on both the left and the right, each meter module section only has 1200A horizontal bus, is this allowed per NEC? Assuming the left side does not exceed 1200A and the right side does not exceed 1200A and the combination does not exceed 1600A.

My eaton rep says this is allowed per NEC but that the city of chicago does not allow it.
Any ideas which code section would govern this?

Thanks for your help.
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Are you asking for a chicagoland code reference?

The NEC doesn't tell you what kind of guts you have to put in a piece of manufactured equipment. If it's rated 1600A by the manufacturer then that's what it's rated.

Eaton is not the only manufacturer that makes meter stacks that are made to be center fed, exactly like you describe and are legit because they are engineered to work that way.
 
I was hoping to figure out the NEC section that allowed it so I could see if the the Chicago code was different for that section. The current chicago code was somewhat based on the 1999 NEC with lots of changes. In March they are adopting the 2017 NEC with amendments.
 
jjs said:
I was hoping to figure out the NEC section that allowed it so I could see if the the Chicago code was different for that section.
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The NEC does not govern the internal components of a listed piece of equipment. Take a look at the second paragraph of 90.7.

 
This may be helpful....looking through a UL 2010 White Book under Switchboards (WEIR).

Reducing the bussing in distribution sections of this type of equipment is a similar application.
Under the paragraph titled USE, INSTALLATION & RATINGS ....states the through bus or supply bus serving the next section may be reduced but should not be less than the supply rating of the next section.
Here is the kicker...the paragraph ends with,
The adequacy of the supply, through, splice, or section bus current rating with respect to the calculated load current using the appropriate diversity factors noted in section 230.42 and art 220 of NFPA 70,
can only be determined by the AHJ at the final installation.
 
How about 240.4 C.
I was not trying to argue for the AHJ, but simply point out the text giving them jurisdiction. Thought it was worth knowing the origin.

Would they need a code citation if the equipment UL listing deferred FINAL approval to the AHJ.
 
electrofelon said:
What would they cite as a code violation as long as the load calc is less than or equal to the equipment rating?
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Whatever code amendment they have enacted, assuming the eaton rep is correct. Remember, this is the city that requires EMT conduit for residential wiring.

The OP may need a 1200A breaker for each side of the lineup, or he might need 1600A buss on each side.

Then the utility will supply the whole thing with 4/0 wire. :)
 
MyCleveland said:
How about 240.4 C.
I was not trying to argue for the AHJ, but simply point out the text giving them jurisdiction. Thought it was worth knowing the origin.

Would they need a code citation if the equipment UL listing deferred FINAL approval to the AHJ.
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I do not think 240.4 applies to bussing/conductors in equipment (except busways).

Protecting something at its rating with an OCPD is not a universal requirement. Its like the 80% continuous load rule that often incorrectly gets applied to all equipment. Note that switchboards are not required to be protected at their rating and often have lower ampacity buss sections than the primary buss or OCPD.
 
MyCleveland said:
Is panel bus NOT a conductor ?
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Not really. Article 310 specifically states that the article does not cover integral parts of equipment. Other articles dont specifically mention that, but as Charlie mentioned there is 90.7.

Where is the NEC rule for allowing ....ex: 400A bus to be protected at say 600A ?
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Where is the rule disallowing it? What type of equipment? There is no general rule requiring stuff to be protected at its rating with an OCPD. For panelboards yes, 408.36. Switchboards, no such requirement. A bussed gutter, no such requirement. Meter enclosures, no such requirement. The closest thing you will find is 110.3
 
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