3 phase sub panel 100 amp

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matt123

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So question, I have a 3 phase 100 amp sub panel that is requiring a 100 amp single phase circuit to power an X-ray machine with a max surge of 100 amps on startup but then runs at 3 amps. Can a couple of light or outlet circuits be added
 
I pulled up a typical 100 amp breaker curve to find the following information:
To allow for inrush, a typical 100 amp breaker allows 1000 amps up to 1 second. It allows up to 400 amps up to around 10 seconds. At around 100 seconds it allows up to 200 amps. Its long time setting or "Infinity setting" allows for 100 amps as expected.
Since it only pulls 3 amps at its long time setting, you should be good to go. You should be able to add many more loads to this since an X-ray is a non critical life support piece of equipment. My two cents.
 
Whats the duration on the 100a? The shorter that time the less its a concern to the point where its not a concern. For example the cold resistance of a 65 watt incandescent is @ 16 ohms With 120v applied that will draw 7.5 amps until it reaches operating temp and draws about .54 amps which equals about 222 ohms.

You could put up to 22 of these on one 15 amp circuit. In that case you would have an theoretical inrush of 165 amps on a 15A circuit until those filaments got up to temp to where they would draw 11.8 amps. I don't know how long that theoretical inrush lasts. Is it one cycle, a few cycles or a fraction of a cycle? I don't know. I have never timed the current drop or seen a graph on filament temp. Perhaps the X-ray manufacture has this in the specs or specifies the circuit size?
 
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