How to size the circuit breaker and feeder for air compressor

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dahualin

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I have a project with two big air compressors. But I am not sure if the air compressors belong to article 430-Motors or article 440-Aire conditioning and Refrigeration equipment. Thanks.:confused:
 
The air compressor is a compressor package with all kinds of protection. But I still need to size the feeder and circuit breaker in electrical panelboard.
 
does the equipment no have a nakeplate data for that ?
 
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The air compressor is Ingersoll Rand 40HP compressor with FLA 59A. From its cut sheet, the suggested main supply cable (feeder) is #3AWG and the suggested fuse rating is 75A. I called the rep. about the suggested fuse rating. He told me that they don't give any MOCP or MFA as other HVAC equipment does. I don't feel very comfortable with the suggest fuse rating 75A, which is too small compare to the Table 430.52 that will give at lease 59x1.75=103A. What do you guys think?
 
I would follow the cut sheet and not have a second thought about it.

Table 430.52 are maximum allowable sizes not code required minimum sizes. Check the title of the table.
 
iwire said:
I would follow the cut sheet and not have a second thought about it.

Table 430.52 are maximum allowable sizes not code required minimum sizes. Check the title of the table.
Click to expand...

I agree, I would also not have a second thought about following the cut sheets for this compressor.

If after you install the compressor there is an issue with 75 amp fuses blowing then at that time you might want to upsize the fuses in accordance with Table 430.52.

Chris
 
The cut sheet shows the suggested fuse rating. I will size the circuit breaker in panel. Circuit breaker is different from fuse based on the Table 430.52. That is why I want to figure out how it works. It seems to me that the fuse rating is just the same as the cable rating (#3AWG). The FLA is 59A. It times 1.25 = 73.75A. It doesn't seem that the fuse is sized for inrush current of motor load.
 
Auestion and a comment, please.
Q:
1. Is the motor wired "across the line" start or is there a drive or other type starter ?

C:
2. If the mfg. had a "suggested' fuse, I would try to determine if they have a required FUSE type protection (even if the size is not mandated). If you protect it with a beaker and they have sepc'd fuse protection you might be in a position of voiding their warranty and technically in violation of NEC.
 
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