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1955 2nd series Chevy Pick Up
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Discussion Starter · #1 ·
Since there are a lot of questions on compressor wiring lately...me too. I am going to install my 7 hp 60 gallon compressor. The tag on the compressor says it is 240 volt, 15 amp, 60 hz, 1 phase. I need to run about 25' of wire from the main box to the compressor. What size wire would I need and breaker.

Also I bought a used electric kitchen oven for power coating. What size wire would I need for that? It will be next to the compressor so the wire distance would be the same. I assume the breaker would be a 50 amp just like my house has.
 

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To maintain a max. 3% voltage drop you'd need 12awg for 25ft. I personally would recommend using 6awg with a 50amp breaker in your sub and a 30amp time delay fuse in a disconnect switch. The surge current could be upwards of 30amps and electric motors can not tolerate a voltage drop for a length of time. Sounds like overkill, but it will save your motor.

-Lou
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are you feeding this air compressor and oven from a existing garage panel ? or from your existing house panel ? or do you need to add a sup panel in your garage to feed these items ?

with the air compressor you can feed it from the panel with 12/3 romex or a conduit with 3 #12s on a 20a breaker (if using fuse's I would still try a 20a time delay fuse) a 20a breaker or fuse will not hurt any thing, as if a 20a is not big enough it will not cause low voltage,it would only trip the breaker or blow the fuse. if the air compressor ever trips the the breaker or blows the fuse then up the size to a 30a (a 30a breaker or fuse is legal on a #12 circuit that only feeds a motor) but I'm guessing / using a educated guess that a 20a over current protection will be sufficient. actually I would over kill the feed to the air compressor to #10awg wire on a 20a breaker or fuse.

now a older range will require or should be on a 40a breaker or fuse with 3 #8s feeding it. but newer ranges require 4 #8 wires and a 40a 4 prong female
receptacle & 40a 4 prong male cord end.

so I would feed the range with a 4 wire #8 range cable on a 40a breaker or fuse, but if it's being run in conduit you could get by with 4 #8s, but I personally would over size the conduit feed to 4 #6s in a 3/4" conduit on a 40a fuse or breaker, and if its a older range with a 3 prong cord & cord end on it, just use 3 of the 4 wires to feed the range. but by running 4 wires if you ever upgrade your range or use the feed for something else the 4 #6s will be there. and #6 can be put on a 50 0r 60a breaker.




Mustangsaly
 

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1955 2nd series Chevy Pick Up
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282 Posts
Discussion Starter · #4 ·
Thanks for the info guys. I am setting up my compressor in the shop area of my office. It is in a commercial building. The panel is a 100 amp 2 phase with breakers. I would be wiring straight to that to my compressor and stove which is 25' away. The panel is pretty much empty except for a few circuits we ran for lights and outlets.
 

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gator412 said:
Thanks for the info guys. I am setting up my compressor in the shop area of my office. It is in a commercial building. The panel is a 100 amp 2 phase with breakers. I would be wiring straight to that to my compressor and stove which is 25' away. The panel is pretty much empty except for a few circuits we ran for lights and outlets.
in a commercial building you need to run everything in conduit unless you can install / encase the feeds in a wall, then you could use romex & a range cable as long as it's protected. if the air compressor & range are close you could run it all in one conduit. if you run it all in one conduit it needs to be over sized, as with 4 current carrying conductors in one conduit the wire needs to be a little larger. with out figuring it, you prob need 2 #10s for the air compressor and a 30a breaker & 2 #6s for the range and one #10awg ground wire that can ground both the range & air compressor.

now if the range calls for four wires, you will probably need a total of 4 #10s. 2 #10awg hots for the air compressor and 2 #6awg hots for the range and 1 #10awg neutral for the range and and 1 #10 ground to ground the air compressor and range.

(a 2 pole 20a & a 2 pole 30a breaker will be the same price) I would look at the tag on the range, but I would think a 40a breaker with #8awg wire is what you need, now if the range calls for a bigger breaker like a 50a then you need #6awg wire.

(check the name tag on your range 1st for the breaker and amperage size, so unless your range calls for a 50a breaker, you need a 30a 2 pole breaker and a 40a 2 pole breaker four #10awg wires and two #6awg wires. )

you need 2 breakers 1 30a 2 pole and 1 40a 2 pole breaker (or 1 50a 2 pole breaker if your range calls for that), for wire you need 2 black #10awg and 1 white #10awg and 1 #10awg green and 2 black #6awg

I Always over size my wire awg size a little if I can.



Mustangsaly
 
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