not heating, but someone here will know.

nick z.

I was always taught electric motors run more eff. on higher voltages. I have a guy telling one of my custmers that a motor will last longer and run cooler on 115, vs. 230. How this come up was it was my job to hook up a large kitchen exh. fan, and a make up air fan.I was told both were 115, but when I got there the exh. fan was marked 230,so thats how I wired it,as soon as I turned it on I could tell it was 115 . I changed voltage and it runs fine, but agian it is tagged 230. The only way to see the motor leads is to remove it.So now the custmer has spent the money to have me run 230 to unit, and the guy that sold her the hood told her he did that special for her because 115 motors last longer and run cooler. Geez I guess these big factories are wasting therer money on 3 phase 440. Thanks for listening.

Jerry Boulanger

My trusty old pocket handbook

tells me that for single phase motors, the nominal current draw at 230 volts is exactly half of the 115 volt draw. For the same power factor, therefore, the electrical draw (kilowatts) is the same. If you go to 3 phase, however, the kilowatt draw is lower, so as long as the power factor is the same, a 3 phase motor is more efficient.

There is, however, a distinct advantage in the size of wire, fusing, etc. for higher voltages/lower amp draws. I also personally do not like single phase motors over about 1/2 hp - I find they are noisier than 3-phase motors.

Frank_17

115/220

Jerry is right. On single phase there is no difference on consumption or life. Was taught that at a well pump school, I argued with the engineer also, and he proved me wrong.

heatboy

No power consumption difference.

We pay for wattage, not voltage. The primary benefit of 230 vac compared to 115 is the wire size because of the reduced amp draw from 230. 3 phase goes one step further.

hb

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Mark J Strawcutter

heat production

I get into a similar "discussion" from time to time with the counter guy at my local electrical distributor. He insists that 220v resistance heaters are "more efficient" than 110v because they draw less amps. sigh.

Mark

Mike T., Swampeast MO

Hmmm...

I've always been taught that 220v motors were more efficient as well--not greatly but they produced less heat which means less wasted energy and [presumably] less wear. Don't 110v vs 200v window A/C units have significantly less efficiency rating for similar sizes?

Have also been told by utility linemen and other decidendly non-deep physics sources that 110v is significantly less efficient than the 220v used in much of the world. Maybe something about the return path to the generating equipment being through the earth for 110v and through the wire for 220v? or something like that? One lineman actually called 110v "direct-alternating current" and explained that much of the true work capacity is lost in the way it is utilized yet recovered with 220v (both wires alternately hot/neutral) applications. According to him it really didn't show up as a lack of efficiency to OUR view with typical 110v or 220v small motors, but to the UTILITY company view as excess transmission loss.

Floyd_3

The key here.....

isn't so much eff., however the electric utility will measure the wattage to bill you for the electric you use by measuring the HIGHEST leg draw...... IF you can run a 120 motor and balance it all the time with a like draw on the other leg.... than there will be no difference... however that wil rarely happen. Therefore being that most of the time the fan will be running and adding the higher load to only one leg, then the percieved use of electric to the utility will be higher because they are taking their measurement off of that higher reading.

Balancing out the loads in a main service box can and will save electric on your bill, especially if it is a small commercial service where you pay by the watt, PLUS, a demand charge.

A 220 window A/C unit will run cheaper, because not only is it running @ half the amps, but, the load is also being balanced across both legs......

Hope I made myself clear.....???????? MAKES SENSE TO ME:-)!!!!!!!!!!!!!!!

Don_4

Motor wiring

I have never been convinced that there is any efficiency gain at either voltage. But, as already stated there can be benefits such as lower wire sizes required etc. The main reason to wire any appliance to 230 volt if possible is that you pay for amperage through your meter. If the amperage is 10 amps through each leg you pay for 10 amps. If the amperage on one leg is 4 amps and the other leg is 16 amps you pay for 16 amps. That is why agood electrician will "balance" a panel.

Mark J Strawcutter

wattage

you get billed for watts (power) not amps. From a very simplified viewpoint, at 220v a device will use half the amps that it does at 110v but because P=VI it's power consumption (watts) will be the same.

Mark

Mark J Strawcutter

Don't think this is correct

I belive single phase meters are designed to properly measure (kilo)watthours correctly no matter how they are consumed and how "unbalanced" the load.

Mark

Tony_8

220/110 window ac

A 110 unit drawing 15 amps uses 1650 watts (VxA=W).
A 220 unit drawing 7.5 amps uses 1650 watts VxA=W).
The difference is drawing 15 amps on one "hot leg" or drawing 7.5 amps on each of two "hot legs". The cost to the consumer is the same because they are paying by the kilowatt, in this example;1.65 kw. It probably costs the generators more to produce the power lost to 120v operation because it basically goes through the appliance to ground and is, essentially, lost. 220v appliances work one phase against the other to produce work and it pretty much stays in the grid. That is how I understand my foreign electrician friend who doesn't understand why we still use 120v systems in the USA due to the inefficiency of the grid as a whole.

Don_4

Billing

Yes you do get billed for watts but if your load is not balanced you will pay for the higher draw even though you may not actually be using the full amount available. The meter isn't smart enough to balance it for you. Your house is supplied with power at 230 volts and the meter spins at the rate of the highest amp draw (leg).

Floyd_3

Amen brother!!!!

That is what I was trying to say....the Utilities will use evrything they can to their advantage!!!!!

Thanks for backing me up on this!!!

Mike T., Swampeast MO

220/110

Thanks Tony for some verification regarding that "return path" thing...

As I recall, the 220/110 debate had a lot to do with the "current war" (AC/DC) and some rather poor decisions at the time.

Tesla (who designed the production, distribution and utilization system we STILL use today) wanted two-wire 220 to be the norm.

For some reason a hot wire and "neutral/return" wire were deemed "safer" although I cannot fathom how/why. I believe that most of the switches available at the time were designed with DC in mind--single pole with a very positive "snap" action to reduce arcing.

Also 110v only required one power wire to be run to homes so it was initially cheaper for utility companies. A surprising number of homes here in my town still use single wire service and during the summer in particular one leg of 220v (measured at three different locations in town) generally lags behind the other by about 6 volts--and I've seen MUCH more.

The cynic in me says, "American companies have never had a problem charging consumers for their own inefficiency/poor decisions."

Mark J Strawcutter

conservation of energy

You could build a 220v distribution system with one wire grounded. You could build a split 110/220 system and not ground any of the conductors. In fact I think the NEC talks about both scenarios.

The electrical energy is converted to heat and mechanical energy in the motor. There is nothing left to return (preserve).

The advantage of higher voltage to the power company is less loss thru the transmission facilities and hence more billable energy delivered to the customer over smaller wires.

Mark

Mark J Strawcutter

\"single\" wire service

Lots of houses around here (most of them student rentals :-) have 110v service entrance. But it's described as a "two wire service" while a conventional 110/220 serivce is "three wire".

I believe one of the earlier arguments, back when AC and DC were competing, for a grounded neutral was safety.

Mark

Mark J Strawcutter

voltage coil vs current coil

Meter has 1 voltage coil parallel across the two hot conductors and two current coils - one in series with each hot conductor.

A 110v load will only affect one current coil, a 220v load will affect both.

Mark

steve_29

208-230vac motors

I have a quick question...

Are 208-230vac motors wired with a neutral with two hots or just 2 hots w/o a neutral...

thanks

Tony_8

no neutral

Don_4

Current coils

You are correct in your statement about the coils but what you are forgettting is the same motor draws twice the amperage at 110 volts as it does at 230. Either amp coil can turn the dial and the one with the highest amp draw does the turning.

Mark J Strawcutter

not forgetting anything

The effects of the two current coils are _additive_.

Drawing half the amperage at 220 but thru both coils has the same effect on the meter as twice the amperage thru one coil when operating on 110.

Mark