Is there a point wiring sub 2hp engines as 220v?

[Don1357]

Your average garden variety 2hp motor draws around 14 amps. On a 20-amp 120v circuit it should be a happy camper. For dual voltage motors, is there any point on wiring them as a 220~240v motor?

I'm sketching the electric layout for my new garage/shop. There are quite a few machines that has dual electric motors such as the 1.5hp Unisaw motor, a 1.5hp Grizzly 6x48 sander, and a 1hp baldor motor on the band saw, to name a few.

 

[bad_idea]

I recently had this conundrum in my shop. I am curious to see what others have to say. Here is what I came up with: You need 12/2 wire to run a 120v 20 amp circuit, you can get away with 14/2 wire to run a 240v 15 amp circuit. Both circuits will power the machine. Difference then is your breakers. You will need a dual pole breaker with the 240v circuit which chews up more box space and costs a couple dollars more. The longer runs will save you money, but only by a little bit. If you have a large box then it may be wise to run the 240v circuits.

I think where it starts to save you money is when you up the horsepower just a little bit. My disc sander is a good example. It is an older Rockwell 12", can't remember the horsepower of it. It draws 30 amps on 120v and 15 amps on 240v. I found it much cheaper to run a 20 amp 240v circuit with 12/2 gauge wire (that I already had on hand) than to run a 30 amp 120v circuit with 10/2 gauge wire (twice the cost of 12/2).

BTW, your thread title is a bit off. Engines usually run off gasoline or diesel, not electricity.

 

[mike93lx]

I would keep them as 120v. Cheaper breaker and you are probably going to use #12 anyway

 

[Chucktin]

Waaaay back when I bought my Craftsman Table Saw I reconfigured it from 110/120 to 220/240. It immediately ran quieter and smoother. Sure maybe I was fooling myself but the extra $ for breakers and heavier extension cable wasn't that much. Still got it, 30+years later and _maybe_ I need to replace the arbor bearings, maybe (still assembling a new shop).

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[mike93lx]

Waaaay back when I bought my Craftsman Table Saw I reconfigured it from 110/120 to 220/240. It immediately ran quieter and smoother. Sure maybe I was fooling myself but the extra $ for breakers and heavier extension cable wasn't that much. Still got it, 30+years later and _maybe_ I need to replace the arbor bearings, maybe (still assembling a new shop).

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Heavier extension cord? You could have used lighter gauge, assuming that what you used on 120v was sufficient.

I am guessing that was the problem, not voltage

 

[Don1357]

Waaaay back when I bought my Craftsman Table Saw I reconfigured it from 110/120 to 220/240. It immediately ran quieter and smoother. Sure maybe I was fooling myself but the extra $ for breakers and heavier extension cable wasn't that much. Still got it, 30+years later and _maybe_ I need to replace the arbor bearings, maybe (still assembling a new shop).

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It is quite possible, but then the question would be how close you were to max amperage on your 110v setup, both for wire gauge and run length. If you were close then it would make sense to see an improvement. I'm wondering specifically for motors running with plenty amperage, like the example 2hp drawing 14 amps on a 20 amp circuit (12ga wire). I also have 1.5hp and 1hp motors that could be wired either way. I'll be using 12ga wire all around except for 14ga on lights.

 

[mike93lx]

Besides the effort to change the motor configuration, you will have to cut off all of the factory plugs and replace them, plus buy more expensive receptacles that prevent you from plugging other tools in

 

[bad_idea]

Pondering this further.... If you install 240v outlets for the items, then that is all you can plug into the outlets. Also, correct me if I'm wrong, by code you are only allowed one 240v outlet on a circuit, meaning multiple circuits. Where as you could wire them for 120v and hook up multiple items on the same circuit because one man can not run a table saw and a band saw at the same time. Also, with duplex 120v outlets you have another outlet available by the equipment for something else if needed. I've never seen a duplex 240v outlet.

 

[Ua189ammoniatech]

I have always wired motors as 220v if I can just to have less wear and tear on the windings less volts more amps more heat faster insulation breakdown on a motor

 

[Bert_]

Most 2hp baldors I've wired recently are about 22 amps on 120. Not going to be happy on a 20 amp breaker.

 

[spudley]

Your average garden variety 2hp motor draws around 14 amps. On a 20-amp 120v circuit it should be a happy camper. For dual voltage motors, is there any point on wiring them as a 220~240v motor?

I rewired my 90's era Delta 1 1/2 hp Contractors saw to 240V after I read the motor kicks up to 2hp @ 240V. Since switching it runs smoother, sounds better and never trips the breaker under load like it did at 120V.

The 120V was plugged into a dedicated 20 amp line so nothing else was consuming power.

 

[Innovate1]

Most 2hp baldors I've wired recently are about 22 amps on 120. Not going to be happy on a 20 amp breaker.

The horsepower is often wildly inflated although in the OP case only a little. 2 hp is 2 x 746 watts/Hp = 1492 watts

120V x 14A = 1680 Watts which is more than the watts of 2 Hp but that is shaft power and doesn't account for losses in the motor or the power factor (voltage not exactly in phase with current).

1492/1680 = 88.8 percent efficient (still not accounting for power factor).

That's an efficiency number that isn't going to happen on that size motor and they are playing games somehow with the numbers. I'd say it's not really 2 Hp.

To the OP question, it really makes the most sense for larger motors as others have said. On 120V larger motors may have trouble starting or start slower due to the large currents and voltage drop at start up. For the 2 Hp motor if it is nameplated at 14A it hardly seems worth it.

 

[sberry]

I leave them at 120 if they work, so much simpler.

 

[TractorJeff]

At 240V, there is less of an issue balancing your Panel Loads, which balances your Feeder load, which balances your Meter load.
Its about using the Power efficiently

 

[mike93lx]

At 240V, there is less of an issue balancing your Panel Loads, which balances your Feeder load, which balances your Meter load.
Its about using the Power efficiently

Shenanigans. A single, intermittent use tool makes no difference whatsoever to balance.

 

[Norcal]

Most 2hp baldors I've wired recently are about 22 amps on 120. Not going to be happy on a 20 amp breaker.

Agreed,1 1/2 HP is the iffy point in the 120V VS 240V debate, 2 HP will not do well on a 20A 120V circuit.

 

[Don1357]

Besides the effort to change the motor configuration, you will have to cut off all of the factory plugs and replace them, plus buy more expensive receptacles that prevent you from plugging other tools in

These are floor machines on a new setup that will have plenty of outlets around. There will be no need to be disconnecting them to hijack their outlets. The question is whether the following statement is true enough to justify the one-time expense:

I have always wired motors as 220v if I can just to have less wear and tear on the windings less volts more amps more heat faster insulation breakdown on a motor

How true is this right here, for say motors that draw 14 amps and below on 20 amp circuits?

 

[mike93lx]

These are floor machines on a new setup that will have plenty of outlets around. There will be no need to be disconnecting them to hijack their outlets. The question is whether the following statement is true enough to justify the one-time expense:



How true is this right here, for say motors that draw 14 amps and below on 20 amp circuits?

I would bet no. Motors run for many years especially home-use stuff, at 120v. You will never recoup a fraction of the added cost, IMO

 

[TRWham]

I have always wired motors as 220v if I can just to have less wear and tear on the windings less volts more amps more heat faster insulation breakdown on a motor

The current through each run winding is the same regardless. When wired for 240 V, you put 2 windings in series and both carry the same current. When wired for 120 V, you put 2 windings in parallel and each carries half of the total.

 

[Cruzan80]

Pondering this further.... If you install 240v outlets for the items, then that is all you can plug into the outlets. Also, correct me if I'm wrong, by code you are only allowed one 240v outlet on a circuit, meaning multiple circuits. Where as you could wire them for 120v and hook up multiple items on the same circuit because one man can not run a table saw and a band saw at the same time. Also, with duplex 120v outlets you have another outlet available by the equipment for something else if needed. I've never seen a duplex 240v outlet.

Not quite true. Anything over 20A needs a dedicated outlet, but you are allowed to have multiple 20A loads on one circuit. Regardless of 120\240. The only "issue" is that a 240 doesnt have a line and a load screw, so you end up using a wirenut to attach Line/load/outlet wires together. Needs a bigger box to be comfortable.

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[yatg]

Leviton 5822

 

[nutjob]

Here's another thought, If you ever think that tool would benefit from an upgrade to a 3 phase motor with a VFD for variable speed you really want to have a 240 volt circuit.

I recently did this to my drill press and I wished I had a 240v outlet close by. I have a 2x72 belt sander on a 120v motor and will swap it out for 2 hp 3 phase so I will need 240v for that. I did not run a circuit anywhere close.

Kevin

 

[mike93lx]

Here's another thought, If you ever think that tool would benefit from an upgrade to a 3 phase motor with a VFD for variable speed you really want to have a 240 volt circuit.

I recently did this to my drill press and I wished I had a 240v outlet close by. I have a 2x72 belt sander on a 120v motor and will swap it out for 2 hp 3 phase so I will need 240v for that. I did not run a circuit anywhere close.

Kevin

If it is a dedicated circuit, the voltage change is not complicated at all. Breaker and receptacle is it

 

[nutjob]

If it is a dedicated circuit, the voltage change is not complicated at all. Breaker and receptacle is it

In both places I still need 120v for outlets, so not an easy change. When I wired the garage 4 years ago never had a need for 240v outlet and thought I never would.

Like so many folks have recommend in the past, put in conduit so it is easy to change as needed

Kevin

 

[mike93lx]

You can also run a vfd on 120v and still get 3phase out

 

[Don1357]

Here's another thought, If you ever think that tool would benefit from an upgrade to a 3 phase motor with a VFD for variable speed you really want to have a 240 volt circuit.

I recently did this to my drill press and I wished I had a 240v outlet close by. I have a 2x72 belt sander on a 120v motor and will swap it out for 2 hp 3 phase so I will need 240v for that. I did not run a circuit anywhere close.

Kevin

A dedicated 12ga wire to a tool is trivial enough to upgrade to 220v, all I would need is the 220v breaker and the correct plug/outlet.

 

[Norcal]

You can also run a vfd on 120v and still get 3phase out

Although 3 phase motors have not been discussed, VFD’s do not play well with GFCI’s.

 

[u2slow]

My welder, compressor, and 2-post lift all work on a 20A circuit, so I already use the t-slot 6-20R in multiple places. One circuit heads out from each side of the panel to cover both shop walls.

I like the crisp starts and balanced loads with 240V, so that's my choice for dual-voltage equipment.

 

[snorky18]

Cons: already discussed.

Reason #1 to wire 240V - less voltage drop
Reason #2 to wire 240V - your wire ampacity goes up

The best analogy I've ever heard for 120 vs 240 (or 240 vs 480) - ever seen those old school mills that were driven by mules or horses pushing a big horizontal wheel in a circle? What's smoother, 1 big horse pushing one side of it (and every stride the horse takes surges the whole system), or two smaller horses that are on opposite sides?

 

[mike93lx]

Cons: already discussed.

Reason #1 to wire 240V - less voltage drop
Reason #2 to wire 240V - your wire ampacity goes up

The best analogy I've ever heard for 120 vs 240 (or 240 vs 480) - ever seen those old school mills that were driven by mules or horses pushing a big horizontal wheel in a circle? What's smoother, 1 big horse pushing one side of it (and every stride the horse takes surges the whole system), or two smaller horses that are on opposite sides?

That's not a good analogy at all. Power doesn't work like an unbalanced load from horses.

Voltage drop doesn't matter when it is small enough

How does ampacity go up? Current carrying capacity doesn't change with voltage

 

[Don1357]

People keep ignoring the premise of the post, a motor running on a circuit where at 110v it is nowhere near the circuit capacity.

 

[bad_idea]

Leviton 5822

Thanks for that! Learned something today.

 

[tonyciambrone]

Shenanigans. A single, intermittent use tool makes no difference whatsoever to balance.

 

[sberry]

I fixed a job one time had a panel 200 ft away on 6. Had 49A on 1 leg and 1 on the other.

 

[strutaeng]

I've got an older Emglo 18 gallon air compressor with GE 2 HP motor set up for 120V. The nameplate FLA is 19A, and it does not trip a 20A breaker, perhaps because the motor amp draw gradually increases as tank pressure increases.

It has wheels, so can plug into different exterior 120V outlets in my backyard.
I can't see a reason to covert it to 240A, unless you believe that "240V is more efficient."

 

[sberry]

If its working normally no reason to change it. For an intermittent user no reason to spend 25$ on materials to save 25 cents of electric and wear and tear over the next 25 years.

 

[Norcal]

If its working normally no reason to change it. For an intermittent user no reason to spend 25$ on materials to save 25 cents of electric and wear and tear over the next 25 years.

The power consumption will remain the same, only the amperes will be halved when the voltage is doubled.

 

[sberry]

There might be a fuzz of heat loss in the wire?

 

[u2slow]

I've got an older Emglo 18 gallon air compressor with GE 2 HP motor set up for 120V. The nameplate FLA is 19A, and it does not trip a 20A breaker, perhaps because the motor amp draw gradually increases as tank pressure increases.

It has wheels, so can plug into different exterior 120V outlets in my backyard.
I can't see a reason to covert it to 240A, unless you believe that "240V is more efficient."

What age & brand are these breakers? And how hard (long) does the machine run? Taken an amp-draw measurement?

You can run lots of things on FPE breakers without tripping...

 

[strutaeng]

What age & brand are these breakers? And how hard (long) does the machine run? Taken an amp-draw measurement?

You can run lots of things on FPE breakers without tripping...

Newish (4 year old) GE breakers on my garage subpanel and new (a few months old) GE on the house (also a subpanel).

The compressor had a constant-run set up with pilot valve when I bought it. I've run it with a needle scaler in my garage for about 15 minutes and I believe it was pumping all the time because needle scaler is an air hog.

Recently I converted it to run-stop (removed pilot valve and added pressure switch) and last job was using air grinder from house outlet with carbide burr bit working on some welds. It was easy a 2 hour job and grinding about 80% of that time with compressor running while I was grinding. Die grinder is also an air hog.

I've taken ammeter readings before on another compressor I put together, but not worried about this one...