Need help with hooking up a 220 compressor

admin

Hey Newbie here! Just bought a remaned 7hp air compressor with the 60 gallon tank for home hobby use and was wondering what I am in for as far as hooking it up. I am thinking about running some heavy 10 gauge wire for it and then using a plug from compressor to wall, instead of hard wiring it in.Figured I would just use a dryer male to female plug units for the install.Anybody see any problems with this?  For what it's worth, I paid 275 for the remaned compressor locally. Figured I couldn't beat it for the price?thanks Ben
Reply:Congrats on the compressor. Glad you got a slightly larger than 'hobby' model. Seems like any sized tool at all and I'm always outrunning the air supply. In compressors, bigger IS better. Anyway, at face value (7hp, 230) you'll need to figure for about 5 amps per horse. So that we be a 35 amp circuit, end to end, breaker to plug. One other thing you should do is look at the plate/tag that is on the motor. It will give you the real amp requirement then size based on that plus add your own fudge factor on the wire for future upgrade.  Many compressor motors aren't quite as heavy on horses as they claim. The amp rating of the motor will tell all.
Reply:Sounds like you got a good plan going.  I just recently purchased a 7 horse 60 gal. tank size myself right after Christmas. If you have an owners manual you might look in it to see what the supply cable wire size should be. I purchased slightly overkill for mine and went with 8/3 wiring and hard wired it into the breaker box. No problem at the breaker box side but when I went to wire it to the compressor I found that my wiring was so big I had trouble getting it routed into the small opening and getting the wires secured properly. I think I would have been fine using 10/3 for wiring, oh well its done and it works great. I also installed one of the $6.00 auto drain kits you can purchase from harbor freight on my compressor. It sure helps to eliminate having to manually drain the water off of the compressor. My new compressor was a replacement for a 5 horse rotary compressor w/25 gal tank. That sucker would run you out of the shop it was so loud. This new compressor is a lot quieter and takes less time to build 60 gal then the other one took to build 25 gal.How are you securing yours to the floor? I borrowed my brothers hammer drill and drilled the three holes for it. Then went to a farm store and bought the expandable studs to use in concrete. I cut some pieces from a 1/2 thick rubber mud flap to place under each foot of the tank. This also was a big help later for installing the drain kit as I needed the extra room. My wife was about flabbergasted when I kept buying stuff in order to get the compressor hooked up the way I wanted it. She couldn't understand that it would not come with a cord for it. Since I placed my compressor at the back of my shop close to the breaker box.  I ended up running air line most of the length of my shop back to my work area.  I had about another $100.00 tied up with purchase of air line, electric wiring, brass fittings to hook up the drain kit, and also put in a ball valve at the bottom of the tank for easy draining and a ball valve coming off the air outlet prior to the air line. As Sandy has stated the compressor ratings are far heavier then what you actually end up with. I think my 7 horse motor actually ends up being about a 3 1/2 motor the 7 horse rating is what they figure is maximum at startup I beleive.Good luck.
Reply:Ben,Assuming that the compressor motor is rated  30A you will of course need to use 8/3 wiring and a 40A breaker. I am not sure what your local codes are, but most places you need to wire 240V machinery directly and a disconnect needs to be within sight. -Stephen
Reply:I just bought an IR 230 volt compressor.  it is rated at 11 hp but that is the starting hp not the running hp.  the running hp is 5 hp.  Anyway, to be safe I went with 6 guage wire and a 50 amp breaker.  I also went with a 3 prong oven plug so I could disconnect it if I needed to.  I have run it a ton so far and the 6 guage wire stays cold.    Mounting: the compressor is an 80 gallon upright model so it came on a pallet.  it weighs 300 lbs so I just left it bolted to the pallet.  I bought some 3 inch wheels from HF and mounted them to the underside of the pallet so I could role it into the corner of my garage where it sits.  I then put shims under the pallet to take the load off the wheels and to keep the compressor more stable.let us know how it goes.
Reply:We need to know the FLA that is stamped into the tag on the motor. Plugs are good and work as a service disconnect. There are some other details depending on where its being wired from, sub or main and what type of recept, surface mount or in a steel box? Really a welder plug would be better, a bit pricier but better,www.urkafarms.com
Reply:hey big muddy,i live down in st. louis, does that place you bought your compressor from have any more???? i was going to buy one from tracor supply but if i can get a bigger better one for less $$$$ that is all good..