New Champion Air Compressor wiring question

[Cadman56]

Just got a new Champion Air Compressor. 5hp, 60gal vertical tank, twin cylinder, 2 stage. Motor is a Baldor Reliance Industrial Motor 5hp, 208/230 volts, 23.5/21.5 amps. I have a 30amp breaker in my shops panel box that is not used. Is this OK to use amp wise? I will be running 8ga wire from the panel to a disconnect. Which leads me to my next question. I have a 30amp disconnect that I used for my old compressor, (2hp, 20gal tank), to turn the compressor on and off. On the inside cover of the disconnect it states that the max hp for the disconnect is 3hp. Can I still use this disconnect? If I can then I'm going to hard wire from the disconnect to the compressor. Note that my compressor does not have a manual or magnetic starter. Attached are couple of pics of the disconnect that I hope I can use.

 

[Charles (in GA)]

Your 3 hp disconnect is not sufficient. Motor rated items take into account extra loads imposed on motor startup. Start with the 30 amp breaker. If it trips on startup, then go up in size to a 40 and see what happens.

Compressor needs to be within 50 ft straight line, and in sight of the disconnect. If you cannot meet this, you need a disconnect at the compressor.

Charles

Charles

 

[Cadman56]

Thanks for the reply Charles. You're right, the disconnect I have in there is insufficient for my application. The breaker box is only 15 ft away from the compressor. I have a 30 amp double pole breaker in there that I'm going to use for the compressor. If it pops the 30 amp then I'll have to get a 40 amp for it. I just want to put a disconnect near the compressor so I can cut the power right there rather than opening the door on the panel and tripping the breaker when I need to do any maintenance on the compressor. I looked at Lowe's today to see if they had any disconnects that I could use for my application, but I couldn't find any. All 30 amp disconnects were 3 hp max. Any suggestions on a disconnect? Thanks again.

 

[Charles (in GA)]

Lowes and Home Depot usually have some 60 amp "air conditioner" disconnects designed to be mounted on the side of a house to disconnect an A/C compressor/condenser unit. They also have 30 amp ones, but 60 amp is quite common and about $12. Not sure about the HP rating but at 60 amps, I'll bet its more than enough.

Charles

 

[Cadman56]

I did look at the 60 amp disconnects. They were 60 amp and rated at 10 hp max. Those take a larger cartridge fuse than the 30 amp I have in there now. Would it be OK to use the 60 amp disconnect? I thought the disconnect had to be the same amp rating as the breaker in the service panel.

 

[Charles (in GA)]

The disconnects I'm thinking about don't have any fuses in them, just a switch or pull out. Really doesn't matter, if the disconnect you install in the line is larger than the one at the panel, the one at the panel will trip first. You could install smaller fuses in the 60 amp rated panel you looked at. They make different families of fuses that are physically different sizes, but each family is available in different amp ratings.

Charles

 

[Cadman56]

Thanks Charles for the info. I'll check them out next time at Lowe's or HD. If I can't get what I need there, there are a couple of big electrical supply houses in my area. I just go to one of them and pick up what I need. Thanks again.