attic addition

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wonderware

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Wanting to put a separate panel in attic for new rooms. I would like to come off the 200 amp main outside to a 60 amp panel for the attic. I think this can be done but would like more info.


Thanks
 
Re: attic addition

Hire a licensed and insured electrical contractor, they will tell you ifand how it can be done.

This NEC? Forum is for those in the electrical and related industries.
Questions of a "How-To" nature by persons not involved in the electrical industry will be removed without notice.
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Re: attic addition

Bryan, this person works in the industrial field and is not up to date on the residential side because it's a lot different. He works on troubleshooting automation and robotics so I am opening this thread up again.

Thanks,
Charlie
 
Re: attic addition

He works on troubleshooting automation and robotics
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The login name is a dead giveaway for anyone who has worked in this field. Wonderware is a HMI software company.

If you come off the main with wire that isn't rated for 200A, it is called a tap (NEC article 240). You will probably have to set a 60A disconnect with a circuit breaker or fuses by the existing disconnect.

Working space and equipment space are two things to watch out for. You should have a 30" wide x 3' deep by 6.5' tall space in front of the panel for "working space"

Thats just a couple of things to think about.

Steve
 
Re: attic addition

I have thought about this also but I wasn't sure about the derating that would need to be taken into account since the attic is generally much hotter than anywhere else.
-Ed
 
Re: attic addition

It's not clear from the OP if these new rooms are part of an attic renovation, or if the attic's just a convenient place for the proposed panelboard. Just a thought: If it's the latter, the attic has to have permanent stairs, an access hatch wouldn't satisfy 110-33(b).

As for derating: Assuming the load for OCPD selection is 60Amps and we're talking about a 120/240 3-wire panelboard feeder with 75C terminals and 90C conductors, #6 Cu has a 75C rating of 65Amps and its 90C rating is 75Amps. Even derated for a 45C ambient (for example, what they allow for normally-ventilated attics in L.A.) at 87%, that's 65Amps. So you'd be OK with a 60Amp CB protecting a #6 feeder to the panelboard.

If you're concerned with keeping the voltage drop to 2% in the feeder, #6 Copper at 60Amps, 120Volts is good for a run of 41-45 feet (depending on how you figure it). If you need a run of 65-72 feet, increase to #4 and if you need a run of 98-114 feet, increase to #2.

The minimum EGC for a 60A OCPD is #10 Copper, but if you increase the conductors for VD, then you have to increase the EGC as well. #4 conductors would need a #6 EGC and #2 conductors would need a #4.
 
Re: attic addition

Could use a little more info . Is this a main switch, a multi-circuit main outdoor panel, a 200A main breaker only, a meterbase only? Could be a feeder, could be a tap. Not enough info right now..
 
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