View Full Version : 110 vs 220 .. again.

10-24-2005, 09:12 PM
I called my utility to find out. 2 phone calls and 4 transfers later....
In residential use 220 isn't going to save you anything powering motors or anything else.
The difference comes into play for industry. Based on a demand billing and power factor it now makes sense to use it. Residential isn't billed on either.

I wondered about this big savings that I've seen written in magazines but it was never explained why 220 would save you money.
Its always mentioned it saves but never why it saved anything.

746 watts is about 1 hp.
6.7 amps for 110
3.3 amps for 220.
Less amps but its still the same billed wattage. Its still 746 watts.

The only saving seemed to me to be starting amps between the two but it should still be almost the same wattage in either case.
If you convert your KWH bill into amps.
Even if the amps are lower your "charged" more for less amps. It costs 2 cents per amp at 220 compared to 1 cent for 110.
Wheres the savings there?
I started thinking what would it cost to add a 220 circuit, buy the plugs and recepticals and figured 220 would have to save quite a bit to be a savings. Now I might use 220 for my electric furnace but it would be just as easy to run 2-20 amp circuits at 110 as one dedicated 220 circuit.

For my wood and metal tools same thing. Why run 220 all around the basement when I can do the same at 110 and have useable outlets?

10-24-2005, 09:59 PM
...Uh, because 120V equipment is piss poor?

Besides, I'd like to see a 120V 100A circuit for a usefully sized welder. That's battery cable you're talking about!

And then there's good old electronics. Which has more power loss for the same power delivered, 120V 20A or 240V 10A? (Hint, power equals resistance times amperes SQUARED.) Economics: which is cheaper (wire, installation, whatever else)?

If you want 240V equipment AND 120V outlets, get both put in, duh!


P.S. Nowhere in the continent is 110 and 220V still used. The mean value *used to be* 117V, hence much equipment from the 40s, 50s and around there was rated as 117V. Since electric companies bill by power (real power, volts times amps, RMS, in phase), it's worthwhile for them to send it as high as possible: accordingly, most outlets across the states are 120 to 125V. (The legal range is +/-5% or 114 to 126V.) If you have any equipment actually rated for 110 or 220V, you should look into getting buck transformers for the pieces, because they may be dangerously sweating off the extra volts.

10-25-2005, 01:33 AM
Well no where did I say anything about dedicated 240 volt massive power loads. 100 amps what world are you from? Yah thats a normal comparision and a 120 volt line can easily handle a load like that. I would like to see that circuit, forget about the wire size just show me the receptical. Good comparision. Half a houses service is a good comparison.

So do the math for me. How much money do I save using a 1.5 hp motor on a 120 volt 20 amp circuit as apposed to a 1.5 motor on a 240 volt 10amp circuit? The resistance is the same isn't it or am I saving like $1 per year of use?
I've heard it and heard it but never saw the numbers so where are they?

I do have some machines that can be wired either way. I'm sure your aware that this exists.

I did check and found 110 volts 115 volts and 120 volt stuff. So whats that supposed to mean? That industry can't decide on how to label it or they can't decide on what the standard is?

10-25-2005, 03:20 AM
Here is an easy test to find out which cost the most to use.
Get 5 110 air conditioning units and 5 220 units and connect them to two seperate meters and run them for 10 hours. While doing this take temp measurements and read what temp these are at and then tell me which one is better.

I will bet you that for the same temperature the 220 will use less kwh.

Oh Tim, most people still call it 220v and 110v, for household use what you call the voltage makes no difference. 220, 208, 240 it's all the same to a homeowner.


10-25-2005, 03:51 AM
I say we throw a coin in the air, and see which side it lands on. Heads= there's a significant savings. Tails= there's no significant savings for using 220 or 219.8456 volts. That's the ultimate in objective and neutral testing.

Or, we could all take a poll, and vote about which side the coin will land on, and not even bother flipping it.

As far as I know, and I'm no electrician, there are savings for using a higher voltage, because of the simple reason that resistance is lower at higher voltages at the same power output as lower voltages. That's why we see all of those 500000 volt "High voltage" lines around. So, yes motors and stuff will be more efficient at 220 V AFAIK.

But is it worth it? How much time and money will be spend changing stuff out, and how much trouble will be caused by having to get different tools/appliances/etc?

I don't know. And perhaps I don't even know what I'm talking about, but I say "NO" to high voltage! We have to protect those poor children. What? You say "YES" to dangerous high voltage?! Child-hater!


10-25-2005, 08:55 AM
To you there is no savings, a kilowatt is a kilowatt. Something wrong with the other reasons?


10-25-2005, 11:42 AM
Personally, since I need 220 anyway (welder), I would run everything that can be run off of 220 off of it, and only stuff that has to be run off 110 off of it. I only use one tool at a time 99.9% of the time so I don't need to worry about circuit capacity too much -- the only things that are on besides whatever I'm using are a radio and a single fluorescent light, most of the time. I'm willing to bet that a comparable system would work well for most of us who have at least one appliance that requires 220. If you don't, well, it's up to you. I like 220. I don't have to worry about finding whomping big wire for my motorized stuff.

10-25-2005, 09:28 PM
LOL, Cyrus I think you'll find that most little children (and adults) get hurt by 110v, though that is probalbly because the opputunity is there. There are a helluva lot more 110 appliances in the home than 220.
Besides those kids gotta learn not to touch it.


hank miller
10-25-2005, 09:30 PM
Well there often is a difference, but it is rarely significant.

For 15 amps you need 14 gauge wire, for 20 amps you need 12 gauge wire, to go to 30 you need 10 gauge.

Your 20 amps 120v device will use 10 amps at 240v, but you will run 14 gauge wire because they don't use anything smaller in construction. So you have less resistance in the wire.

Wire resistance decreases the voltage to the motor. Your motor because it is drawing less voltage than rated puts out less power. However your motor still wants to draw 745 watts at full load which means more current, but more current in the wires increased the voltage drop in the wires, which means even more current is needed. Thus lower voltages result in a vicious cycle, as your power goes down the motor slows, meaning it draws more current, which lowers the voltage even more.

Somehow the above also makes the motor more likely to overheat, but I can't recall the relation here.

240 helps in two ways. The obvious is you are more likely to have over sized wires, which decreases the voltage loss. Even if this isn't the case though, a 2 volt loss works out to a 2% loss at 120 vols, while the same 2 volt loss at 240 volts works out to just 1%. This percent loss is what gets factored into the extra current your motor needs to draw.

If your tools are right next to the break box, all this is insignificant, as you won't have significant line losses anyway. The farther you move from the break box (and also the lower the voltage your utility supplies), the more important it is to run at 220 volts.

V = IR. Or R = V/I. Double the voltage and you can safely double the resistance before resistance becomes significant.

If your tool is going to sit in one place (that it is isn't portable for practical purposes), by rights, and by code it should have a dedicated circute. As long as you are running wires anyway, you may as well run 220 just in case it matters.

10-26-2005, 08:44 AM
Well, to me at least 100V (here) is the biggest PITA and waste of time, effort, energy and money I can think of.

I came from Oz, where it's all 240v. So coming from the country with the highest single phase mains to the country with the lowest of the same, it's a big jump, and a rude one at that.

Take a common extension lead, in Oz @ 10A, I have a potential 3hp sitting at the end of that lead. Here, @ 15A, I have maybe 2hp. The lead itself is significantly larger, I can't run it as far without losing precious voltage, and I can't run it as hard without it getting warm, again losing precious voltage.

OTOH, the 100V system is fairly safe. If you get a zap, there a pretty good chance that nothing is going to happen to you, unless you have a weak ticker. 240V is a decent zap, and is more likely to stop a someone ticking. Moot point in the times of earth leakage circuit breakers, AKA: GFI.

Add in the fact that in lower voltages, most equipment is down on power, simply because the juice isn't there. At 240, you can have a hand held drill with 2.5hp. Big drill, but you can have it. :)

I run my welder @ 200V, but I had to run a circuit to do it. Not something I am keen on doing every time I need an outlet with proper jucie available.

But enough of that, I think I am being fairly obvious.

100-110-120V at the outlet just doesn't really cut it, when compared to 220-240V. In outright costs on paper, 240 should run cheaper, but there's more than that in the real world. Heck, you could blow the apparent saving to heck if you have a poor connection at the outlet. ;)

02-16-2006, 06:39 AM
220-240V has the advantage that electric components like vires can be made by a smaler dimension and motors can be smaler than for a 110-120V system. A smaler motor require less kw to keep itself running.

So for 220-240V require less instalation cost because you can use smaler fuses, switches and wires + you will save money on your airconditioner, washing macine and other motor runn components. If you only use electrics for ligh you will not see anny diference on the bill.