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Electrical confirmation

1K views 7 replies 5 participants last post by  kbsparky 
#1 ·
Hello Member;

Looking for some confirmation. I am installing a subpanel in an attached garage. Approximately 70 ft from the main panel. I am using 10/3 wire to feed the subpanel. I am looking to connect 2 pieces of equipment to the subpanel. One machine is 30amp/250v ( machine A )and the other is 20amp/220v ( machine B ). These machines would not be used at the same time.

My question is if I wanted to add a third piece of equipment which is 10amp/220v ( machine C ) would it be possible to add this circuit to the subpanel. This third piece of equipment ,machine C would only be used at the same time with either machine A or B

Max current draw for machine A is 28 amps and machine B is 17 amps, machine C is 10 amps ( based on nec 430/ 430.148)

Nec 310.15 b states that at 90C 10/3 handles 40 amps

Machine A + C = 38 amps ( potential concern ???)

Machine B + C = 27 amps ( not a problem)


Would the above set-up be ok? Time delay 30amp breaker?

Thank-you for your help
 
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#5 ·
Based on 430.24

Machine A ( 35amps) + machine B (17A) + machine C (10A) = 65 amps

which would require 6/3 wire?

My question is if I only plan to use machines (A + C) or (B + C) at the same time does the above still need to apply?

A+ C= 52A B + C= 27 A I believe this would allow 8/3 conduit?

Thanks
 
#8 ·
....My question is if I only plan to use machines (A + C) or (B + C) at the same time does the above still need to apply?

A+ C= 52A B + C= 27 A I believe this would allow 8/3 conduit?

Thanks
You are not required to include the smaller motor in non-coincident load situations.

But you only need add the 25% to the largest motor value.

Therefore A + C = 45 Amps. #8 THHN wires in conduit would be sufficient for this load.
 
#6 ·
Is this all the machinery you will EVER put in this garage? I always chime in on these sub-panel threads with the warning that you will be sorry someday if you have too little power, but you will never cuss at yourself for having too much power.

I understand that most of us have a limited budget to work with. I'm only suggesting that you either save your money for just a bit longer or neglect the kid's shoes for a month or so. Cutting the installation to the bare minimum (or even under the minimum) can be a no-win situation.

I speak from experience. I am now machinery rich.... I own machines now that I NEVER DREAMED of having when I built my garage 15 years ago. I have stuff I didn't even know I wanted until it just happened. But I never had to turn down or scale back a hobby for lack of power to run the tools. The wife can MIG weld (yes, she does) while the 7 1/2 HP compressor builds up pressure and the I'm on the mill or lathe making metal chips. I never dreamed back then....

Just a consideration.
 
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