Any benefit to run DC on 110 vs 220?

[Scott Winter]

I have the option to run either voltage on my 1.5HP DC. Will I see any benefits running one versus the other?

[johnny means]

No. There are certain situations where 220 will help with less than ideal electrical service. It won't, however, perform any differently.

[John Kananis]

I prefer to wire anything I can to 220v over 110v. There's less current draw for one. Especially something like a DC since it draws a bunch when you first start it up.

[Mike Henderson]

Technically, it will perform exactly the same on either voltage (and it's probably 120 volts and 240 volts, not 110 volts and 220 volts). However, as John points out, running it at 240 volts will cut the current in half so you can use smaller wire for the circuit feeding it. Losses in wire are I (squared) R so cutting I in half cuts the losses in the wire by 4 (given the same wire in both cases).

And it will also cut the inrush current on startup - and the losses in the circuit during that time.

Mike

[John K Jordan]

I have the option to run either voltage on my 1.5HP DC. Will I see any benefits running one versus the other?

It depends mostly on the size of the wire and the length of the run from the panel (assuming the panel has plenty of capacity.)

A longer run with the same wire size will have higher resistance. More resistance will cause voltage drop under load. Voltage drop can affect motor performance and in extreme cases can overheat and damage the motor. (The type of motor typically found on shop machines will try to develop the rated HP by drawing more current if the voltage drops, causing more drop, causing more draw, etc…)

However, you are unlikely to have problems in a typical shop unless the wire is undersized for the motor amperage and length. In that case, if the motor is convertible, powering with 220v instead of 110v will require 1/2 the amperage. You can use an online voltage drop calculator to compare the voltage drop with both voltages.

I can give you two examples of where using 220v made a difference. One: In a previous house the shop power was fed underground from the house where the panel was on the far end of the house and the tiny shop (actually more of a shed) was about 40’ from the house. The total run was fairly long. I don’t remember the wire size but it must have been marginal. The biggest tool was a Craftsman radial arm saw. Using the same wire I switched the power and motor to 220v. Instantly the saw came up to speed quicker and had more power.

Another example: many years ago my BIL had an electric water pump in a spring house a long way from his house, evidently too long from the house for the amperage and wire size. He burned up one motor after another, seemed like every six months to a year. After switching to 220v powering the same HP motor he never burned up another motor for the next 10 years he lived there.

When I built my current shop I did the voltage drop calculation for the 250’ underground run from the main feed near the house. I believe the generally acceptable voltage drop is around 3%. I decided to go with larger copper so the worst case voltage drop would be closer to 1%, even in the unlikely case where multiple things were all pulling power at the same time. The cost of the wire was more but compared to the total cost of the shop I considered it insignificant.

JKJ

[Bill Dufour]

I have seen voltage drop distance tables done two ways. The way I was taught is to take the length of the wire run and double that to look up. Some tables already have the distance doubled so they are direct reading. Make sure you understand which way the table you are looking at is designed.
Bill D

[Frank Pratt]

As long as the installation is wired to code, there will be no difference in power, efficiency or performance.

[Charlie Velasquez]

Another consideration is how your poco bills you for electricity.
The amount of energy used will be the same, so your kilowatt/hrs will not change.
But pocos usually have ancillary fees.

I have experienced “meter charges”, “facility charges”, “peak hour charges”, “demand charges”, and others.
Some of those are fixed, such as the meter charge, but some are variable.
One that was our school district nemesis is the demand charge, similar to peak hours, kinda.
Demand was computed by taking the greatest amount of amps used during any 15 minute interval, then multiplying by our service rating.
The meter measured each leg separately then took the highest value to compute the demand.

When I started our district’s energy program I discovered the industrial arts welders were mostly drawing from one leg of our service. By distributing those welders evenly within the panel we saved thousands of dollars.

Wiring at 240 will help balance the load, which can reduce lights dimming and such, and possibly save you money.

[Mike Henderson]

For single phase induction motors, anything over about 1.5HP is probably best run on 240 volts. At least that's what I do.

Mike

[Frank Pratt]

For single phase induction motors, anything over about 1.5HP is probably best run on 240 volts. At least that's what I do.

Mike

I agree with this strategy. It means less wire cost and concern with voltage drop. I do the same.

[David Bassett]

To answer the question in the heading: No.

In theory they will perform the same. In practice 240V will usually work better and the only reason to use 120V is you have no choice. (Like in my garage which seems to have a single 15A circuit, 'cuz the only thing you'll ever need is a garage door opener, right? :( )

[Eric Arnsdorff]

The answer to this is somewhat similar to the variance of responses in this thread.

It comes down to what you have available. If you have the higher voltage available (or installable) it becomes preferred because of voltage drops, smaller breaker ratings, line sizes and current induced heating. If you only have the lower voltage available then you can almost completely compensate for the voltage drops and current induced heating with larger lines and larger breakers. There always is some benefit from running at the higher voltage due to reduced current and heating effects in the motor itself. But with larger wiring, breakers, connections, etc. performance is essentially the same.
However, the lower voltage has costed more in cabling, interconnects and requires more current draw resulting in a larger breaker and more load on the phase it is on. Another item is motors can have high inrush currents and the higher voltage helps with this as well.

There are impedance effects that higher currents (lower voltages) do produce a less desirable response from. For shop equipment it is almost always the case that ultimately the higher voltage will be somewhat advantageous in terms of performance. You will notice better transient responses using the lower current (such as startup, loading, etc.). But in the application of woodworking equipment it certainly isn't a show stopper to use the lower voltages.

If I only needed it for a single 1.5 hp or so piece of equipment, I may choose to stick to the lower voltage. But in a shop you quickly build up multiple machines that it starts making more sense to run the higher voltage lines which are smaller and don't draw as much current.

[Mike Henderson]

Just a correction to Eric's comment about an advantage to running a motor at a higher voltage giving a reduced current and heating effect.

The way dual voltage motors are wired is that they have two sets of coils. When the motor is wired for low voltage (120 volts) the coils are in parallel. When the motor is wired for high voltage, the coils are in series.

When the coils are in parallel (low voltage), the current is double the current when in series (high voltage) but only half of the current goes through each coil and the voltage drop across each coil is 120 volts.

When the coils are in series (high voltage) the motor only requires half the current as when wired for low voltage and that current goes through both coils (in series). The voltage drop across each coil is 120 volts, half the high voltage of 240 volts.

In either case, the voltage and current in the coils are identical and the heating effects are the same. There's no free lunch.

Mike

[Bill Dufour]

120 does have one advantage. It can be switched with a single pole switch on the only hot leg. A 240 circuit needs a two pole switch, to be safe, one pole for each of the two hot legs. So a 240 volt switch is harder to find, costs more, and requires a trivial increase in wiring time at the switch box.
Note that any proper motor contactor can be used for 120 or 240 and the control voltage can be 24, 120 or 240 depending on the coil. The coil can be replaced with a different voltage one if needed.

Bill D

[Frank Pratt]

120 does have one advantage. It can be switched with a single pole switch on the only hot leg. A 240 circuit needs a two pole switch, to be safe, one pole for each of the two hot legs. So a 240 volt switch is harder to find, costs more, and requires a trivial increase in wiring time at the switch box.
Note that any proper motor contactor can be used for 120 or 240 and the control voltage can be 24, 120 or 240 depending on the coil. The coil can be replaced with a different voltage one if needed.

Bill D
Well, harder to find in that you may have to reach up to the next shelf to get the 2 pole switch and just a few bucks more for a 2 pole commercial spec grade switch. Any contactor you find in a shop machine, unless it's very old, is highly unlikely to have a replaceable coil. The contactor will most likely be an IEC rated one and they in the smaller sizes have no serviceable parts. Some of the old iron with have a NEMA rated contactor, which are much larger and can be completely disassembled and serviced.

[Greg Funk]

Just a correction to Eric's comment about an advantage to running a motor at a higher voltage giving a reduced current and heating effect.

The way dual voltage motors are wired is that they have two sets of coils. When the motor is wired for low voltage (120 volts) the coils are in parallel. When the motor is wired for high voltage, the coils are in series.

When the coils are in parallel (low voltage), the current is double the current when in series (high voltage) but only half of the current goes through each coil and the voltage drop across each coil is 120 volts.

When the coils are in series (high voltage) the motor only requires half the current as when wired for low voltage and that current goes through both coils (in series). The voltage drop across each coil is 120 volts, half the high voltage of 240 volts.

In either case, the voltage and current in the coils are identical and the heating effects are the same. There's no free lunch.

MikeWhen starting, in either case, you won't be getting 120V across the coils. The locked rotor current can be 5-10x the full load current which can produce a significant voltage drop even if your wiring is up to code. The voltage drop will be less in the series (240V) configuration. Running off of 240 will generally bring the motor up to speed faster. Whether that makes a difference is another matter.

[Rollie Meyers]

120 does have one advantage. It can be switched with a single pole switch on the only hot leg. A 240 circuit needs a two pole switch, to be safe, one pole for each of the two hot legs. So a 240 volt switch is harder to find, costs more, and requires a trivial increase in wiring time at the switch box.
Note that any proper motor contactor can be used for 120 or 240 and the control voltage can be 24, 120 or 240 depending on the coil. The coil can be replaced with a different voltage one if needed.

Bill D

The NEC permits a 240V single phase load to be switched only with one leg, and a 3 phase load switched with only 2 poles, as long as it is not the disconnect, and it is a very common practice in packaged air conditioning units, my point is that it is not a preferred practice, it is not wrong to do it that way.

[Eric Arnsdorff]

Just a correction to Eric's comment about an advantage to running a motor at a higher voltage giving a reduced current and heating effect.

The way dual voltage motors are wired is that they have two sets of coils. When the motor is wired for low voltage (120 volts) the coils are in parallel. When the motor is wired for high voltage, the coils are in series.

When the coils are in parallel (low voltage), the current is double the current when in series (high voltage) but only half of the current goes through each coil and the voltage drop across each coil is 120 volts.

When the coils are in series (high voltage) the motor only requires half the current as when wired for low voltage and that current goes through both coils (in series). The voltage drop across each coil is 120 volts, half the high voltage of 240 volts.

In either case, the voltage and current in the coils are identical and the heating effects are the same. There's no free lunch.

Mike

Mike I agree that if you only look at steady state and assumed the voltage at the motor was exactly the same as ideal (120/240). But the first thing is the line losses leading up to the motor will be more in the lower voltage case and the V/f variances will cause differences. Additionally, my use of all motors in my shop are much more in a transient than steady state constant load case which cause even more differences.

I completely agree that it is completely functional if you only have the lower voltage. But there are a number of reasons why you get improvements using the higher voltages.

[Mike Henderson]

Mike I agree that if you only look at steady state and assumed the voltage at the motor was exactly the same as ideal (120/240). But the first thing is the line losses leading up to the motor will be more in the lower voltage case and the V/f variances will cause differences. Additionally, my use of all motors in my shop are much more in a transient than steady state constant load case which cause even more differences.

I completely agree that it is completely functional if you only have the lower voltage. But there are a number of reasons why you get improvements using the higher voltages.

The differences you mention are in the circuit feeding the motor. If the circuits are properly sized so that the voltage drop during startup or running is the same percentage in either the 120V or 240V case, the motor will perform exactly the same and have the same heat characteristics.

The problem is that the circuit feeding most motors running on 120V does not meet that requirement so you get better performance on 240V.

Theoretically, they're the same. In real world situations, 240V operation often works better because of the circuit.

In general, I prefer to run any motor over about 1.5HP on 240V.

Mike

[Rod Sheridan]

120 does have one advantage. It can be switched with a single pole switch on the only hot leg. A 240 circuit needs a two pole switch, to be safe, one pole for each of the two hot legs. So a 240 volt switch is harder to find, costs more, and requires a trivial increase in wiring time at the switch box.
Note that any proper motor contactor can be used for 120 or 240 and the control voltage can be 24, 120 or 240 depending on the coil. The coil can be replaced with a different voltage one if needed.

Bill D

Partially correct.

Starters and switches for 120 volts need to have twice the current carrying capacity at 120 volts as they do at 240 volts.

This increases the starter costs in many cases since you have to go up a size for 120 volts for the same motor power….Regards, Rod

[Ron Hampe]

Amp draw is higher on 110v and you will need a larger wire gauge and breaker. Power consumption is identical though.

[Ron Hampe]

Most tools come with a switch so why would you need a separate one?

[Curt Harms]

Another consideration is what else if anything is on that 120 volt circuit. A typical 120 volt circuit is could be pulling 15 amps just running a 1.5 h.p. motor under load. Add in a few lights or a TV upstairs or who knows and lights dim/flicker or breakers trip. 240 volt circuits are less likely to see additional loads. I imagine this would mostly be a consideration in basement shops.