Size of Electrical Boxes

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Old 08-08-07, 05:10 AM
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Size of Electrical Boxes

Am upsizing my 200 amp service to 320 amp service and wonder why the new service boxes are so much larger than the old. The old meter box and load center total about 40 inches top of meter box to bottom of load center. The new boxes are about 30 inches each which needs a footprint of more than five feet top to bottom. Is there something in the code book that states these boxes have to be this size?
 
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Old 08-08-07, 07:21 AM
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2 main reasons (that I'm aware of):

- The larger service requires significantly larger service entry wires, which are a bear to bend and work with. The extra space allows the wires to run around the perimeter and bend as needed.

- More circuits (?). Does your new load center have more positions/circuits than your old one?

Also, maybe it's because they assume you may have larger loads coming into your load center. On a 100A panel, they assume you probably won't have any #1 wires coming in for circuits/subpanels, whereas in your 320A panel, numerous 100 or 200A subpanels are probably anticipated.
 
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Old 08-08-07, 05:47 PM
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clearances from grounded parts at higher amperages are also one reason, the US only allows 42 circuits max per panel, at this time anyway
 
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Old 08-08-07, 08:18 PM
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Originally Posted by hbsparky View Post
clearances from grounded parts at higher amperages are also one reason, the US only allows 42 circuits max per panel, at this time anyway
current does not affect proximity of the wires to anything. As a matter of fact, voltages within an insulated conductor is nt even relevent.


as Zorfdt stated, one of the biggest reasons for a larger can is the conductor sizes. Wires have a code limited bend radius and since a higher amperage meter and service will need larger wires, the can would need to be larger to allow for those conductors and allow enough room to allow the required radius of the bends.

Since the conductors are larger, they also would simply need more space any place they run. And as Zorfdt stated, there would be more room allowed for larger branch circuit conductors as well.
 
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