220v or 110v for a small 2hp compressor?

[SteveL]

Getting a new 2hp compressor and it’s available with either a 220v plug or 110v at the same cost. What is the advantage, if any, of running it off of 220v? I already have 220v access at the location but could easily convert to 110v if needed. My thinking is that buying it with 110v plug would make it more flexible should I move or need to relocate it down the road, or want to sell it at some point.

 

[u2slow]

A 2hp is usually convertible between voltages. Change the motor connections and a different cord whip.

The advantage starts at 3hp (240v). Approx 10cfm@90psi. Still only needs a #12/20A circuit.

 

[Metal-Marc]

My thinking is that buying it with 120v plug would make it more flexible should I move or need to relocate it down the road

This.

 

[mike93lx]

The advantage of 240v is half the current draw at startup, lowering voltage drop. Will it matter? Not really. And you will lose flexibility.

 

[strutaeng]

What model are you looking at getting?

I've got an older Emglo 2HP 17 gallon (?) and it's wired for 120V. It's nice that I can wheel it around and hook it up with a heavy extension cord.

 

[SteveL]

Looking at the 10020CHAD 2hp 10gal horizontal. Would be placed under a workbench with doors to hide everything. It will be hooked up to hard copper lines that run to a basement shop and ceiling mounted 50’ hose reel in the garage. Replacing an older 5hp 80gal that was hard wired to 240v using 10-3 wire. At only 70 decibels, it’s quite enough to keep the wife happy as it’s up against the living room wall.

Since there are 4 wires, 2 hot, a neutral and a ground, I can either put in a new Nema 6-30 240v outlet using the two hots and the ground or a new 20 amp 120v outlet using one of the hots, the neutral and the ground.

 

[strutaeng]

Ok, gotcha. This probably doesn't matter, but a 2HP compressor will put out more like 8CFM. My old Emglo's GE motor nameplate has like 19A at 120V. I think it's rated at like 8.1 CFM @ 100 psi.

For that small motor, I would definitely stick with 120V.

 

[SteveL]

This one is rated at 6.4cfm @ 40psi & 5.3cfm @ 90psi. Plenty for what I’m going to be doing. I’ve gone mostly cordless battery for just about everything that I need now. Use to have a blast cabinet and needed the big cfm but it’s gone now.

 

[MBfreak]

Supply wiring joule losses and motor winding resistance joule losses will be 1/4 on 240 compared with 120 V,
FWIIW

Ola

 

[Norcal]

A 2 HP motor will trip the breaker if wired for 120 volts, a 1 1/2 HP is iffy at best when run on 120V.

 

[mike93lx]

A 2 HP motor will trip the breaker if wired for 120 volts, a 1 1/2 HP is iffy at best when run on 120V.

Checkmate

 

[Norcal]

You w

Checkmate

You will spend way more to source a ITE or Siemens panelboard that accepts those obsolete BQ frame breakers. It will still be cheaper to wire it for 240V then source rare circuit breakers in any make or frame type, in these times when materials are scarce.

 

[mike93lx]

You w

You will spend way more to source a ITE or Siemens panelboard that accepts those obsolete BQ frame breakers. It will still be cheaper to wire it for 240V then source rare circuit breakers in any make or frame type, in these times when materials are scarce.

Buzzkill

 

[Norcal]

Buzzkill

Not sure how to react to that one.

 

[SteveL]

It comes as 120v from the factory and I can easily put in a 30a breaker with a 20a GFCI outlet and use the black, white and ground from the existing 10-3 cable. Or currently have a 30a double poll breaker in the panel that was used for my old 5hp compressor that I can use the red, black and ground to put in a new Nema 6-15P outlet to match the factory installed 240v plug.

This is from the manufacturers website for the 120v version:

* 110v / 60 hz

* Low Amp Draw - 14 Amps

* Dedicated 15 amp outlet -14 gauge 25ft cord - Min. 5500 Watt Generator

And this for the 240v version:

220v / 60 hz / (No 208 Volts)

* Low Amp Draw - 7 Amps

* Plug Type: Nema 6-15P

 

[Norcal]

If 14A/7A is correct it is not a 2 HP motor.

 

[jlv03]

I can easily put in a 30a breaker with a 20a GFCI outlet

Probably not if you want to meet Code...

 

[Norcal]

Probably not if you want to meet Code...

Agreed & 14A should be fine on a 20A circuit. If it really was a 2 HP motor there would be a problem running at 120V.

 

[wyliesdiesels]

It comes as 120v from the factory and I can easily put in a 30a breaker with a 20a GFCI outlet and use the black, white and ground from the existing 10-3 cable. Or currently have a 30a double poll breaker in the panel that was used for my old 5hp compressor that I can use the red, black and ground to put in a new Nema 6-15P outlet to match the factory installed 240v plug.

This is from the manufacturers website for the 120v version:

* 110v / 60 hz

* Low Amp Draw - 14 Amps

* Dedicated 15 amp outlet -14 gauge 25ft cord - Min. 5500 Watt Generator

And this for the 240v version:

220v / 60 hz / (No 208 Volts)

* Low Amp Draw - 7 Amps

* Plug Type: Nema 6-15P

7a @ 240v is definitely NOT 2HP. Its closer to 1 or 1.5HP

 

[SteveL]

You are correct and I should have said put in a new single pole 20a breaker with the 20a GFCI outlet. I can only assume that the manufacturer is not making false claims about their hp ratings and at the end of the day, I really don’t care if it’s a true 2hp anyway.

 

[mike93lx]

You are correct and I should have said put in a new single pole 20a breaker with the 20a GFCI outlet. I can only assume that the manufacturer is not making false claims about their hp ratings and at the end of the day, I really don’t care if it’s a true 2hp anyway.

HP ratings are notoriously overstated. Look at shop vac for a great example. Those are locked rotor amp ratings. Shenanigans

The math is simple. If it isn't drawing over 750w per HP while running, they're fudging numbers. 2hp is 1500w, and motors aren't 100% efficient.

 

[Walkers]

Nice thing about the 240 volt is the nice easy starts, and also the ability to not be able to be borrowed because most will not have an outlet.

 

[WisJim]

I usually hook up tools for 240 volts rather than 120 if I have the option because that means less voltage drop in the garage and shop and less likelihood of overloading the circuits. My garage circuit is on a 60 amp breaker from the house and the breaker doesn't care if I'm using 60 amps of 120 volt loads or running twice as much wattage at the same amperage at 240 volts. In effect I can run twice the tools at 240 volts as I can a t 120.

 

[nadogail]

I see it as the difference between six or a half dozen. There is a valid point in statement that you can decline requests from those who don’t have an appropriate source of power to run the compressor.

 

[tool_scrounge]

HP ratings are notoriously overstated. Look at shop vac for a great example. Those are locked rotor amp ratings. Shenanigans

The math is simple. If it isn't drawing over 750w per HP while running, they're fudging numbers. 2hp is 1500w, and motors aren't 100% efficient….

…and the motor power factor is always less than one, so it even worse than that. I really hate the BS HP numbers they publish

 

[sparky 1971]

Buzzkill

These are easier to source, less costly, and a lot less likely to cause nuisance tripping. Just use one pole for 120 volt.

 

[mike93lx]

These are easier to source, less costly, and a lot less likely to cause nuisance tripping. Just use one pole for 120 volt.

Winner.

 

[PoorUB]

HP ratings are notoriously overstated. Look at shop vac for a great example. Those are locked rotor amp ratings. Shenanigans

The math is simple. If it isn't drawing over 750w per HP while running, they're fudging numbers. 2hp is 1500w, and motors aren't 100% efficient.

No argument at all. But when motor efficiency is in the mix in reality 1HP is probably over 1000 watts.

My go to numbers are 10 amps per HP on 115 volt, 5 amps per HP on 230volt many of the newer motors are a bit more efficient so slightly less amps, like a fraction, some are less efficient. The real 5 HP on my compressor has 27 amps on the name plate.

 

[mike93lx]

No argument at all. But when motor efficiency is in the mix in reality 1HP is probably over 1000 watts.

My go to numbers are 10 amps per HP on 115 volt, 5 amps per HP on 230volt many of the newer motors are a bit more efficient so slightly less amps, like a fraction, some are less efficient. The real 5 HP on my compressor has 27 amps on the name plate.

Absolutely. I was just giving a bare minimum

 

[dave*99]

A 2hp is usually convertible between voltages. Change the motor connections and a different cord whip.

The advantage starts at 3hp (240v). Approx 10cfm@90psi. Still only needs a #12/20A circuit.

Usually they are convertible. I looked up the manual on this unit. It does not appear to have a dual voltage motor. It also has an AC powered automatic drain down solenoid valve. And that part would also need to be convertible.

My educated guess is this unit is not convertible.

 

[PoorUB]

Absolutely. I was just giving a bare minimum

Some guys get hung up on the 750 watts per HP. Using my 5HP as and example it comes out to 1240 watts per HP.

I wonder if this motor isn't a bit more than the 5 HP rating on the tag. It will start my two stage compressor without unloading the pump without hesitation.

 

[wyliesdiesels]

No argument at all. But when motor efficiency is in the mix in reality 1HP is probably over 1000 watts.

My go to numbers are 10 amps per HP on 115 volt, 5 amps per HP on 230volt many of the newer motors are a bit more efficient so slightly less amps, like a fraction, some are less efficient. The real 5 HP on my compressor has 27 amps on the name plate.

That 5HP motor is either very inefficient or its more than 5HP because ive seen many 5HP motors that are 23a FLA....

 

[PoorUB]

That 5HP motor is either very inefficient or its more than 5HP because ive seen many 5HP motors that are 23a FLA....

Yep! I wonder too as it will start my 5 HP compresser without unloading the head without hessitation. It is an older motor, maybe 40 years old, back when manufacturers were still building them to last instead of a price point. I put an amp mater on it once and it runs well under rated amps while running under a load.
If I needed a bit more air, (I don't!) I would not hesitate to bump the motor pulley up a 1/2" or maybe 1" in diameter. My compresor is also rated for more RPM with a 7.5 HP motor so I was thinking trying to pull about 6 HP out of it, but again, I decided I don't need it.

 

[u2slow]

Guys... don't confuse poor efficiency with power factor. Not the same thing. Motor efficiency differences are minimal these days.

A single phase motor that nameplates less FLA than table values is normally using capacitors to keep it down.

 

[CGT80]

My old 5hp Baldor 213t 1-3/8" shaft motor has a nameplate of something like 28.5 amps. The new 184t 5hp baldors are around 24 amps. Both at 17xx rpm and 1.15 service factor. x2 on the over rated HP numbers being a joke.

 

[PoorUB]

The only reason I question the actual HP is because the motor never draws full amps, even with the compressor at 175 PSI. So either it can handle more load, or the amp rating is generous.