Wasn't saying you were trying to get a free lunch, just some of the outrageous HP and air volume claims on the cheaper compressors I saw advertised when I was shopping compressors, especially the CH ones, were a physical impossibility. If you can squeeze the budget and you have the power available, go for a 2 stage 2 cylinder unit that runs on a 30A 220 circuit. That will have the capacity to do almost any needs you might have, tools, HVLP painting, etc. Still won't run a large sandblaster like to do a complete body with, but will run a cabinet blaster, medium size pot. If you need to do a larger job, rent a gas powered trailered compressor/sandblaster for a day. Oh and avoid the HF and similar low end air tools for continuous use i.e. DA sander, panel sander etc

 

I'm in the same boat. I had a detached garage built in my backyard, wanted 100 amp service. But it would have cost $25k because my house only has 100 amp service, they'd have had to go all the way back to the transformer (underground service, and xfrmr is in my neighbor's yard). So I settled for 50 amp.

The compressor has a huge starting current, the welder doesn't. If you have a switch on the compressor, just flip it off while you're actually welding.

 

Talk about planning ahead

 

Buy the best compressor you can afford. It will greatly expand your capabilities. My next one will be a two stage. Last two were large single stage 220V units with 60G tanks. Moderately priced and somehow lasted 15 years, but they sure take a beating, and media blasting is painfully slow. The ability to go in the back yard and blast a part is so handy for those of us restoring trucks.

 

Being delivered this week..


Schulz 7580HV30X-1 V-Series 7.5-HP 80-Gallon Two-Stage Air Compressor 230V 1-Phase

 

Yeah, Ross, it's kind of a dance out there, turning one thing off so another can be used.
Ax, just kidding about the free lunch. Thanks so much for the info.
GLR, the breaker in the house flipped. It's two 20 amps together.
I'm not defending the wiring in my house. I think it was built on a Friday or a Monday. If I up the breakers in the house to 30's, I'm afraid it would not be safe.

 

Forgot, make sure you get a cast iron compressor head with oil an supply in it, stay away from aluminum oil-less compressors unless you are already deaf. I think anything two stage would be cast iron.

 

Looks like you have 220v to the garage at 20 amp. You're right...no 30 amp breaker unless you really up your fire insurance and make sure family, pets, tools, yourself and vehicles are safe.
I see an electrical update in your future......

 

I was barely getting by with a 110 volt 2 HP unit with a 12 gal tank. Had to wait for air to build between impact gun hits. I watched and waited for a deal on a good one that would last me forever. I finally bought an Ingersol-Rand 5HP 60 Gal Tank 175 PSI 220 Volt unit. Needed a 30 Amp circuit. Two stage cast iron pump runs pretty quiet and is 100% Duty Cycle.

I found it on sale at Sears when they stopped carrying them. Floor item clearance price was great. I have seen them used on CL a few times too. Totally worth it.

Take your time and find the best you can afford. Deals are out there.

 

Yes, I waited a long time from the time I moved from Buffalo where my brothers and I had the shop in my parent's back yard to work in until I could build this one here where I would plan in my head exactly what I wanted. I designed the building and the contractor had it signed off by engineer. The power company here does not charge to run the electrical service to the building either above or underground as long as I signed a document saying it was not for commercial use. I had 200A 220 service run in to the garage on it's own meter.
I included a good number of such small (and some not so small) but significant details to the build.

 

When I built my barn/shop 22 years ago I ran a 100 amp feed underground. The house had a 200 amp panel. The lights will still dim momentarily when the 7 1/2 hp compressor starts.

 

Ditto here to the word
Those big compressors pull some power when they start up.

 

I worked for years with a 30 gal 110v air compressor and it was OK for occasional jobs. As I started doing more work I considered as you have adding an additional air reservoir but never did it as that really doesn't solve the problem. It just means that you don't run out of air quite so fast.

I replaced it a couple years ago with a 60 gal 220v and it was a great improvement. It lets you consistently run better quality air tools which means you can do better quality work.

 

Did you guys know that compressed air, are about 96% losses........

Its the law of physics and it is what it is....

This means that if there is a tools that is electric and does work as good as a pneumatic version, go for that one.

 

One thing that has not been mentioned, and is an avenue worth exploring when setting up your garage/wiring/service/equipment, is to consider foregoing the single phase world, and stepping up to three phase.

While many here probably aren't located where 3-phase is available, it still may be worth your while to go that route if you plan on having numerous powered equipment such as a mill, lathe, drill press, compressors of course, and other things.

The benefits are multiple:

Motors last LOTS longer.
Greater HP output from a given rated motor.
More efficient/less costly in the long run.

And, industrial grade tools, such as 3-phase compressors, can often be had at very reasonable used prices.

If you don't have access to 3-phase power, you can cook your own through a rotary phase converter. Not as efficient as the real thing, as there are losses in HP and longevity. But these losses would be negligible in a home shop/garage setting.

As an example of longevity: Family started a machine shop in the 1940s. I ended up with it in the early 90's, and closed it in '98. Kept the shop, but moved it out to the country. Since all the old machines were three phase, I had to install a phase converter. Except for the compressor motor, ALL the motors on the machines are still original. Many of these motors are in excess of 70 years old. The compressor motor had to be replaced a few years ago because I fried it. Forgot to cut the power one day, and it tried to start on single phase. That motor didn't take too kindly to it, and let all it's smoke out.

Low cost: When the shop was in the city, and I was running it on a daily basis, my electrical bill was only about twice what I paid for residential. Now, and even with the phase converter (which has losses), the base bill for the shop is about $46 per month. This is just with three fluorescent lights burning, and the outside security light, and no machines running. If I am at the shop for four weekends in a month, and spend approximately 8 hours per day for an average of six to eight days total, my bill may get to $88. I have never seen it hit $90 since 1998 when I had the building built. When out there, the first thing I do after turning on all the lights, is fire the converter, then the compressor. After that, I use whatever lathe, grinder, mill, press, etc., to do what I need to accomplish.

In a nutshell, single phase bites. If you plan on ever having any more than a few basic tools, dispense with it, and go for three phase.