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Old 01-27-2012, 10:56 PM   #1
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wire size and OCPD in mixed phases


I've got a 3 phase 200amp 120/208v 4 wire + ground sub panel panel that will be supplying five 3 phase machines with an FLA of 7 amps each and 5 single phase machines at 120v with an FLA of 10 amps each. Totals would be 35amps and 50 amps respectively. I don't know how to plug in these mixed numbers into my wire calculation table.

http://www.electrician2.com/calculat...cpd_ver_1.html

I need to determine the minimum wire size needed and the appropriate OCPD to put in my main panel that will feed this sub described above. All the loads will be non continuous.

The 200 amp panel was the only size I could find with enough spaces to hold all the breakers.

thanks,
David

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Old 01-27-2012, 11:04 PM   #2
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wire size and OCPD in mixed phases


if the single phase loads are divided as equally as possible(2a, 2b, 1c, etc.), you'll have a maximum of 55A on one phase.

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Old 01-28-2012, 03:30 AM   #3
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wire size and OCPD in mixed phases


How big is the main service ?
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Old 01-28-2012, 07:02 AM   #4
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wire size and OCPD in mixed phases


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Originally Posted by n175h View Post
I've got a 3 phase 200amp 120/208v 4 wire + ground sub panel panel that will be supplying five 3 phase machines with an FLA of 7 amps each and 5 single phase machines at 120v with an FLA of 10 amps each. Totals would be 35amps and 50 amps respectively. I don't know how to plug in these mixed numbers into my wire calculation table.

http://www.electrician2.com/calculat...cpd_ver_1.html

I need to determine the minimum wire size needed and the appropriate OCPD to put in my main panel that will feed this sub described above. All the loads will be non continuous.

The 200 amp panel was the only size I could find with enough spaces to hold all the breakers.

thanks,
David
This is obviously not a home improvement DIY job.
Hire a licensed, insured electrician.
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Answers based on the 2008 & 2011 NEC.
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Old 01-28-2012, 11:03 AM   #5
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wire size and OCPD in mixed phases


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This is obviously not a home improvement DIY job.
Didn't you hear? Converting your garage to a laundromat is the latest craze.
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Old 01-28-2012, 08:38 PM   #6
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wire size and OCPD in mixed phases


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Didn't you hear? Converting your garage to a laundromat is the latest craze.
You're right. No garage. It's on hold for now. I'm still waiting on the AEP load engineer to give my electrician a quote for a 3 phase changeover. However, for my own knowledge, I would like to know how to compute the wire size and OCPD for the load described in the original post.

Plummen, the main service will be 400a 120/208 3 phase.

Seems to me it would be 35 + 30 = 65 Three of the five 10 amp single phase machines would be on one 120v phase. I appreciate the knowledge shared on this forum even if it is above and beyond DIY

David

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