I am getting ready to order a 60 gallon two stage air compressor from Harbor Freight. The reviews seem to be good on this unit.

I am going to use it for lite sand blasting, some iron chairs, etc. I plan to install it in my shed running a 240V line to it. I want to run a hose from it to the outside through a hole in the shed.

Here are the specs on the unit:
Electrical Rating
240VAC / 60Hz / 22A
Air Outlet Size
1/2″ -18 NPT
Air Pressure
Shut-off
150 PSI
Restart 125 PSI
Air Tank Capacity 60 Gallons
Air Flow Capacity15.8 CFM @ 90 PSI 16.4 CFM @ 40 PSI
Sound Level 88 dB @ 3′
Oil Capacity 24 oz.
Oil Type SAE 30W, non‑detergent, Air Compressor Oil

Here are my questions:

Should I use a 30A or 40A circuit breaker in my home panel?

Can I use a 50' 3/4" hose running to the outside from the compressor as all of my use will be on the outside of the shed.

What size adapters hose fittings do I need? Can I use 1/4" to the sand blaster? It has a 1/2" fitting on it but I can convert it to what ever is recommended.

I guess I need to purchase an air/water filter so as not to clog the sand blaster, correct?

Any help would be appreciated..
Thanks,
Bob

 

Welcome to the forums Bob!

I'm not an electrician but would think a 30 amp circuit would be what you want since it draws 22 amps.

A larger air hose will move more air but would be restricted if the fittings are smaller than the hose. It doesn't matter a whole lot how long your hose is although the further you get from the compressor you might loose a little psi. A moisture and debris filter is always a good idea. It will be more effective at removing the moisture farther away from the compressor as the compressor heats up the air making it more difficult to remove the moisture.

 

Ideally, I think a quick connect with a cutoff valve permanently piped to the outside of the shed would be best. That way you can seal any holes you make. Some sort of flex connection to the piping on the inside would cancel the vibrations. Then connect the hose to a little portable manifold with the filters on it, then connect your working hose to the manifold or connection. You could easily make something on a small cheap hand truck that would hold all your hoses and tools.

As to the circuit, I think 30A would probably be large enough as well. How far away is the she from the main panel?

 

Thanks for the replies.
The main panel in the house is about 100' away. Was going to run 10/3 UF underground to the shed. Have 110V already buried and working for the lights.

Since the air outlet size on the compressor is 1/2", should I just use 1/2" hose with 1/2" quick connect fittings?

 

That will have to be abandoned since you can't have two power supplies to a detached structure. You will need to install a subpanel. Probably 8-3 on a 40 amp 240 breaker will be adequate. If you are not familiar with the rules for a subpanel post back.

Tech Notes: Your house has 120v not 110v. The compressor would need 10-2 not 10-3.

 

I have a main panel and sub panel in my basement. I think If I understand you, you are saying that I need to run another subfeed from the main panel on a 40 amp 240 breaker to the shed via 8/3 into another a sub panel.
Then out of the shed sub panel, a 120V line on a 15 amp breaker via 14/3 to the lights and 10/2 on a 30 amp breaker to the air compressor?

 

Not a pro but I think you would only need 14/2 for the lights on the 15 amp breaker.

 

(Your post has been moved to electrical because of the electrical portion of your question.)

Yes, 14-2 for the lights. If the existing subpanel is closer to the shed and has room depending on its actual load you may be able to run from there. If the compressor does not have a cord you would connect with a whip (flex conduit with two conductors and a ground) from a junction box near the compressor.

I'd suggest a 20 amp circuit not 15 for lights and receptacles. A 12 space 100 amp main breaker panel kit for the subpanel. You will need to buy a ground bar to add to the panel and an 8' ground rod to install at the shed.

 

Meant 14/2. No, the main and sub panel are in the basement about 75 to 100' from the shed. Thanks for the electrical advice. I should be able to handle that now.

 

What is the horsepower of the compressor motor. I'd base my breaker selection for the compressor by the horsepower and not running amps.

 

60 gal. 5 HP 165 PSI 2-Stage Air Compressor

 

Full-load current for a 240 volt 5 horsepower motor is listed as 28 amperes. I suspect you have a "compressor duty" motor and if so it is NOT really 5 horsepower. At any rate, I would use no less than #10 wiring with a 30 ampere circuit breaker.

 

I agree with using #10 wire, but was going to guess you'd need a 40 amp breaker for the motor to start without tripping. The Square D Motor Data Calculator says you can use #10 wire and up to a 60 amp breaker or 40 amp dual element time delay fuse.

Single Phase Motor Data

 

It may indeed require a 40 ampere CB to start reliably but it is best to use the smallest CB that will allow it to start reliably. Since the full load current is as low as it is (22 amperes) It might do just fine on a 30 ampere CB.

 

This is what the manual states and I assume it is for it's own power supply:

Voltage 230V / 1 ph
Full Load Amps 23
Breaker Size 40 amp

 

The manufacturer's instructions always take precedence over generic instructions.

 

If the manufacturer says 40 amps then you should run 6-3 UF-b* and use a 60 amp breaker in the main panel to supply the subpanel.

*#6 UF is good for 55 amps but since you probably can't find a 55 amp breaker the NEC allows you to round up to 60a.

 

If the shed is not heated, I'd consider installing it in the basement right beside the fuse box.
100' of air hose is MUCH easier to set up than 100' of new wiring.
And you can use your tools year round.

If you do locate the compressor in the shed, don't cut a hole in the wall,
just take a 1/2" notch out of the bottom corner of the door so the door will close over the hose. When you're not using the hose, a small sliver of insulation is all you need to block the hole.

Yep.
I had good results over long distances by using a 1/2" connections and a "click-in regulator".
Instead of screwing the regulator onto the tank, I put a 1/2 quick connect on the tank, a 1/2 nipple and 1/2 quick connect on the regulator. Hoses have 1/2 connections as well.
That way, if you're working 100' away, you have a 100+ psi in the hose going TO the regulator. (Same idea as electric using high voltage transmission towers, then lower voltage distribution)

You want a large ball valve at the tank for easy on/off.
That also lets you keep pressure in the tank
Pickup an automatic drain valve from HF, takes a bit of cobbling to get it to work correctly, but it's worth it.

I'm a big fan of going with the 1/2 quick connect fittings.
You WILL notice a difference in the performance of high-flow tools.

Eh, not much use on the sand blaster, but you will want a filter and auto-oiler if you have other air tools - wrenches, drills etc.
See, unless you are in the tidewater area of Virginia, I wouldn't expect that humidity will be able to clog the sand blaster.
Basically, EVERY compressor will have air at 100% humidity, simply because compressing air at sea level pressure (0 psi relative = 14 psi actual ) up to 150 psi relative (150+ 14 = 164 psi actual) will ALWAYS drive your tank humidity up to 100%, unless you're in death valley where humidity is below 10%.

 

Wow, I hadn't thought about putting the compressor in the basement and just running 100' 1/2" hose to the shed area where I will be sand blasting. I'm in Northern Va, Manassas actually, so you are saying that I shouldn't need a filter for moisture??
Thanks for answering all my questions also. Really appreciate it.

 

The humidity plays a big part in how much moisture a compressor will produce. The other main factor is how often/long the compressor runs. When I was in fla, draining the water off of the tank and filter was sometimes an hourly deal. Here in tenn, I drain off the water at the end of the day. I used to do a lot of painting so I wouldn't be without a water separator. Both of my regulators have a water filter trap incorporated in them. You could start without a water separator and add one later if you need it.

 

Sand blaster - it won't care about humidity.
- It will want as much air flow as you can give it.
Basically, you'll likely be running a sand blaster with the largest hose you can,
no regulator, straight to the blaster.

Quick engineering check, a 1/2 inch pipe (steel in the table) providing ~15 CFM will loose a few percent psi. Nothing you would likely notice at 90 psi.
http://www.engineeringtoolbox.com/pr...pes-d_852.html


Mechanical air tools - grinders, cutters, drills impact wrench, - put an in-line oiler in and they should be ok, quite simply, ALL air tools work at 100% humidity, as far as the compressed air goes.

Painting - THEN you need a water separator - and it should be as far from the tank as possible,
they separate air from liquid water (cool and condensed) but don't work for water vapor (warm air direct from the compressor)

Your mileage may differ, but I make a habit of leaving my air compressor pressurized.

Theory (at least), that lets the tank cool down, that condenses the water out of the air.
Result is cool air which has much less water in it.
So, when you run the compressor, the tank starts with cool low-moisture air, and you have less condensation in the lines.

Add an auto drain, and then when the compressor comes on, it should automatically drain the condensed water out of the tank with each filling. (Of course you can do that manually by letting the tank cool, THEN draining the bottom stopcock.)

Basically, if you take a 0 PSI tank and fill it to 125 psi, compressing the air leads to a tank full of hot high pressure air with lots of water vapor in it.

If you install a ball valve and leave the tank pressurized when you're not using it, that leads to a tank full of cool high pressure air, with all the water vapor wrung out of it.
Burp the drain valve before you start using the compressor, and you remove the condensed water from the air.

I would replace the standard PITA bottom of the tank drain valve knuckle-buster fitting with a simple "T" fitting. One side gets a plug and you can add an auto drain line later.
The other side gets a 3' whip hose, the other end gets an air gun or a simple ball-valve that lets you remove water BEFORE you start using the compressor.

 

Thanks for the info Hal.
I picked the compressor up today. After checking the prices for all the electrical items I need I think I will install it in my woodworking shop In my basement. I have a 240V circuit in there already that I can tap into. One is to my dust collector and the other to my band saw. I will never be running the compressor at the same time as either of those machines so the currently installed 30 amp breaker should be fine.

 

Except, the manufacturer's instructions said to use a 40 amp breaker. It might work and it might not, but you can always run a new circuit if it doesn't work.

 

Just to clarify, when I said "I drain off the water at the end of the day" I meant that I open the petcock just long enough to expel the water but basically leave the tank full of air.

Inline oilers might be ok but they render the air hose useless for painting as the oil residue will come out of the gun and mess up the paint job

I'd rethink using a 30 amp circuit if the specs call for 40. A compressor draws the most amps when it comes back on and having to reset the breaker when the compressor restarts [even if only occasionally] could get old fairly fast.

 

Now, yes you should follow the manufacture's installation instructions,
but I'm not so sure about how much weight to give the HF instructions.
Their paperwork is not exactly know for it's clarity...

But, a quick search reveals that this should be a made in the USA compressor,
these generally have AO-Smith motor compressor motors-

Now, given the low price for the entire compressor,
you're almost certainly looking at the low-end motors,
the CP1502L 19.7 amps, or the B813 at 22 amps.

IIRC, if it's a 19 amp motor, then a 30 amp breaker is ok.

That will depending on which motor you actually have installed.
(I assume the assembly floor is motor-roulette)
And, I'd check how many amps it actually uses with an amp meter.

 

Finally received a reply to my questions from HF customer support:

"This compressor is currently on sale on our website for $799.99. The compressor requires 22A while running, so a 40A or 50A dedicated circuit would be best to power it. A 3/4" air hose is fine, but you would need to have a suitable fitting that can connect to the 1/2"-18 NPT air outlet fitting on the compressor. You can use any type fitting on the other end of the hose that will match up with your tools, you just need the correct adapters or couplers to allow them to connect. An inline oiler and filter are always a good accessory to have when using air tools to keep them working correctly. Our inline filters and oilers are typically 1/4"-18 NPT, so you would need to purchase fittings for those as well if you want to use one of ours."

By the way, it seems that the local home stores don't carry much in the 1/2" fittings line. Not even a 1/2" ball valve or 100' 1/2" hose. Looks like I will be ordering on-line,

 

Which means, use #10 wire and a 40 or 50 amp breaker. When they say a 40A or 50A circuit, they do not mean to use #8 or #6 wire.