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understanding ratings on distro


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a gig i am doing is providing me with a 100 amp three phase distro. the pa supplied uses six 20 amp circuits, two for tops, and four for subs. the only thing i can think of that makes this work is..do i have 100 amps per leg of the three phase? or is something amiss here.

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Safety always comes first with electrical, so please don't plug in/energize any distro if you are not authorized and qualified. If you have specific questions about the venues distro, please talk to someone qualified who is familiar with your specific situation.

 

I can tell you that, in general, The distro's we deal with are rated in amps per leg (120V). for a 100A 3 Phase distro that would be 300A total at 120v.

 

In some many cases, it is permitable for a single phase distro (example 100A) to have more than 5 20A circuits. Keeping in mind that the distro must still be limited by an appropriate beaker (100A in my example)

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i do have a licensed electrician to help with this, but i didnt understand the raitings and now that i do i'm a whole lot less worried about it. safety first as you say, these guys know what they are doing, but because i didnt when it came to the distro, i had to ask.

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The standard terminology is 120/208V, wye connected, 100A, 3ph, 4 wire plus ground.

 

This will be 100 amps per leg, 3 legs referenced to a Y connected neutral.

 

Each 100 amp leg will be 120 volts referenced to neutral, and can have as many 20 amp branch circuits as you want, subject to the 100 amp per leg total. This 100 amps feeder, as well as the 20 amp branch circuits must be properly protected by CB's or fuses.

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