3 phase panel

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  #1  
Old 02-28-07, 08:27 PM
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3 phase panel

I am looking for info on how to calculate for load on a 3 phase panel

I.E ........100 amp. 120/208 panel and i have (Some # Watts). Do i simply divide the Watts by volts(208) to see if this size panel will be appropriate. Or am i missing something.
cheers
 
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  #2  
Old 02-28-07, 08:41 PM
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to make load caluation on 3 phase panel and 3 phase system are little more trickier than single phase system.


i will give you a quick example

for line to netural load [ single phase ]
watts / volts = amp

line to line [single phase ]

watts / volts = amp

line to line [ 3 phase ]

watts / volts / 1.73 = amps


but becarefull with figureing with 3 phase load it little more compated but if you can give me some figures i will get the correct answer there


Merci , Marc

if the figures are wrong let me know at the same time i will double check my chart as well to make sure i get it right
 
  #3  
Old 02-28-07, 09:13 PM
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updated info

my figures came out right just let you know that the " / " is divison

but want to head up being a 3 phase system genrally used in commercal area but very rare it do have in home [ super large home ]

so the way to load demand figures are more trickier and there are some code issuse will show up on this one as well


Merci , Marc
 
  #4  
Old 02-28-07, 09:34 PM
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The panel is in a workshop....120/208 ...100 amp. Load requirements are as follows

Basic 6272.5w
equipment 14000 w these are all single phase motors varying from 1-3 hp
heat 16000w 100% 1st 10k... 75% remainder considering this commercial/ industrial workspace

Total load 36272.5

Appreciate your help...Show your work so I see how it unfolds
cheers
 
  #5  
Old 02-28-07, 10:17 PM
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ok but you did not mention the electric heating device is on single phase or three phase because it will affect the figures

and what i useally do is list the indiduval motors first [ how many motors and how many will be running the same time ]

second the lighing load and others as well senice you listed basic stuff at 6272.5 W

that need to break down some more so i can do the load demand figures better this way


if this heater wired for true 3 phase

16KW = 44.41 amps [ 3 phase but if wired on single phase it will run at 77 amps ]

i always figure the heating or A/C which ever is larger and use that nameplate rating

lighting load genrally useally 3 watt per sq foot [ but this can change depending on what conferation it will be ]

other genral loads have to be listed as well

but back to the point here how many sq feet the building you have ?

and if you have office space i will count that sq footate as well and main area in commercal /wharehouseing area as well

i cant give you the drict answer but you mention 100 a 3 phase service in fact my option it is too small you need 200 amp service anyway


let me know the other figures

merci , Marc
 
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