Understanding how to size a circuit conductor
Let's say I have a device, a time machine perhaps, that I will be hard wiring into my panel with it's own breaker. On the label, next to where it says "1.21 gigawatts", it says that minimum ampacity is 52 amps and maximum circuit breaker size is 60 amps.
Per the NEC, which of those numbers (beside 1.21 gigwatts ) should I use to determine conductor gauge, and why? 
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Is this really just an AC unit? 
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I'm trying to keep it general by not actually telling you what it is. If it matters, then I'm hoping that will just be part of the answer. 
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Dugly :cool: 
Circuit/breaker sizes go from 50 to 60 amps.
52 is greater than 50 so do the math. #6 When you get it up and running, find me when I'm about 10 years old and tell me to move to Seattle and befriend a "Mr Bill Gates". :thumbup: Give John Lennon a heads up too. 
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Use awg #6 fused at 60 amps

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It certainly DOES matter what it is. A/C's, motors and welders all have dedicated sections in the code and follow certain rules. Time machines do not have this luxury.

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I understand why you'd use a 60 amp breaker as apposed to a 52 amp one... 
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I thought that the difference was between continuous and intermittent rating, and that a continuous rating changes the wire gauge needed for a particular amp rating. In other words, a heat coil drawing 50 amps might require #6 wire, while a motor drawing 50 amps might require #5. 
In your case, 52MCA & 60 Max OCPD, the answer is still 60A and #6.

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If your time machines factory nameplate says minimum ampacity 52 amps then you need to size the conductor based on that amperage. Which would be a #6 awg copper conductor or one with a higher ampacity. The max breaker is just that 60 amps maximum. You can't use a 50 because it is not sufficient for the load served. As said several times there is not a 55 amp breaker so next protection size after 52 amps is 60. Motors are 1.25 times the largest plus the sum of the rest, if a single motor then 1.25 times the flc of that motor. If the equipment is a continuous load (will be operating for 3 hours or more) then it is 1.25 times the rated ampacity of that equipment. If however a nameplate states minimum ampacity then continuous or whatever has already been factored in and the equipment must be served with conductors that have at least that minimum ampacity.

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