Service panel AMP rating

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danscape

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this may sound like stupid question...
let's say i have 120/240 V 100 AMP panel and have single load using 240 V and 50 AMPs......
have i reached 100% of panel rating since both hot wires are loaded with 50 AMPS, or i'm just at 50% ?
 
danscape said:
let's say i have 120/240 V 100 AMP panel
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A 120/240 volt 100 amp panel is capable of supplying 24,000 watts of power non-continuous or 19,200 watts continuously.

240 volts x 100 amps = 24,000 watts

and have single load using 240 V and 50 AMPs......
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If that single load actual draws 50 amps it uses 12,000 watts of power.

240 x 50 = 12,000

have i reached 100% of panel rating since both hot wires are loaded with 50 AMPS, or i'm just at 50% ?
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24,000 - 12,000 = 12,000.

This is an oversimplification as it ignores power factor but it gets us close enough for this.
 
Bob provided an excellent textbook answer. If you had only 120 volt loads then you could have a total of 200 amps (100 amps between each ungrounded conductor and the neutral). If you had only 240 volt loads (100 amps between the two ungrounded conductors) then you could have a total of 100 amps.


So in your scenario a 50 amp 240 volt load would use 50% of the capacity of a 100 amp panel.
 
Understanding that the example was meant to be simplified, I must interject that the panel is capable of 24 KVA not 24 KW.

As described someone could be misled because the panel can actually only handle a lesser amount of watts, which as we all know is dependent on the power factor of the loads.
 
infinity said:
So in your scenario a 50 amp 240 volt load would use 50% of the capacity of a 100 amp panel.
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Would this mean that each of the two legs would be carrying 50% of the total allowable loads (50% on one lege and 50% on the other) Is it safe to say that in this example that each leg or pole of the breaker is capable of supporting up to 100A no matter what combination of loads were put on them?
 
mull982 said:
Is it safe to say that in this example that each leg or pole of the breaker is capable of supporting up to 100A no matter what combination of loads were put on them?
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To kingpb's answer, let me add that an amp leaving the panel on one leg does not know whether it will return to the panel on the neutral or on the other leg.
 
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