load calculations for 480 volt 3 phase 30 amp recepticals

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kwired

Electron manager
Location
NE Nebraska
Hi, I was wondering how to figure out the load calculations for several 480 volt 30 amp recepticals, 3 phase? Does 220.44 apply to this?

Thank you,

Charlie
What is intended to be plugged into them? Until you have something IMO there is no load to calculate.

You could have a portable machine that plugs into it, but has several receptacle locations where it can be used. If there is only one machine then you will never have any more then that one load operating at one time even though there is multiple receptacles.

With 15 and 20 amp 120 volt receptacles it is a different ballgame as there is a lot of equipment that can plug into those at almost any site or occupancy type.
 

KD4315

Member
I agree with kwired. Receptacles themselves have no load. You need to know what you're plugging into the receptacles. It's a 3 phase 30A outlet so it's on its own 3 circuit home run so load shouldn't be an issue. You'll plug a 3 phase 30A plug into it. Unless I'm missing something here



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JFletcher

Senior Member
Location
Williamsburg, VA
Welcome to the forum Charlie.


Maybe he is asking what the maximum KW draw would be from a machine plugged into a 480V 3ph receptacle? If so:

kW = (V × I × PF × 1.732) ÷ 1,000.

480V x 30A x 1 (assumed) x 1.732 / 1000 ~ 25kW, or ~ 30HP. If 220.44 applies, 25kVA would be 100% of the first 10kVA, then 50% of the rest (7.5kVA), for 17.5kVA.
 

kwired

Electron manager
Location
NE Nebraska
Welcome to the forum Charlie.


Maybe he is asking what the maximum KW draw would be from a machine plugged into a 480V 3ph receptacle? If so:

kW = (V × I × PF × 1.732) ÷ 1,000.

480V x 30A x 1 (assumed) x 1.732 / 1000 ~ 25kW, or ~ 30HP. If 220.44 applies, 25kVA would be 100% of the first 10kVA, then 50% of the rest (7.5kVA), for 17.5kVA.
And we need machine information to determine this. If we only have receptacles but nothing designated to plug into them - do we have a load? Do we have multiple loads if there are several of these around the facility? Like I said maybe you have a portable machine but several places it can be located. But if you only have one of those machines then the load to use is for a single machine. Get a second machine and you would need two times that load in your load calculations.

If someone is going to specify a 30 amp 480 volt receptacle chances are they have something in mind to supply at some point.
 
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