220 volts/230 volts/ 240 volts: What's the diff?

[Ches]

220 volts/230 volts/ 240 volts: What\'s the diff?

Other than the obvious (a difference of 10 or 20 volts), what exactly is the difference when a piece of equipment is rated at 220 volts vs. 230 volts, or 240 volts? The reason I am asking is that I placed an order for a Millermatic 175 mig welder this afternoon. The specs say the required input is 230 volts, 19.5 amps. My shop has it's own service line (and meter) for which nothing is using elect. unless I am using a piece of equipment. The shop has the 110 or 120 volt circuits in addition to a 220 volt circuit (or is it a 230 volt circuit or is it a 240 volt circuit?). The circuit panel has a circuit breaker (double) that says 120/240 volts. I'm wanting to make sure my shop electrical service can supply the required 230 volts/19.5 amps required for the MM175. So, what's the difference and must you use a tester to determine what you have? Thanks

 

[Bird]

Re: 220 volts/230 volts/ 240 volts: What\'s the diff?

Ches, there are bunch of guys on the forum who are much, much more electricians than I, but the simple answer to your question is that 220, 230, and 240 "usually" mean the same thing, just as 110, 115, and 120 mean the same. Check your voltage with a multimeter sometime and you'll find it varies a bit. I don't think I've ever seen one that was "exactly" 230 volts; maybe anything from about 225 to 235 though. Your breaker panel should have two 120 volt legs, and a double breaker is hooked to both legs while the single breakers are hooked to just one leg, and could be either leg, although you kinda like to keep the load reasonably well balanced between the two. It's actually quite simple, BUT if you've never done it, get someone to show you how the first time 'cause it can bite you and sometimes bites hard./w3tcompact/icons/wink.gif

 

[Phred]

Re: 220 volts/230 volts/ 240 volts: What\'s the diff?

I am sloppy about this and should be more precise. But then you will find that I am not alone. Lots of people are sloppy about this issue.

But the bottom line is its 120V and 240V.
A transformer on the pole feeds your house with two 120V lines and a "neutral" which is just a ground connection.
The two feeds are out of phase and sinusoidal at 60 Hz, which is just a fancy way of saying they alternate between a negative and a positive voltage every 1/60 seconds. The key bit is the out of phase, which means that when one is negative the other is positive. So if you measure the difference between them you get the sum or 240V.

In your breaker box you can get 240V with a wide (double) breaker that taps into the two out of phase leads or 120V by tapping into one and using a "neutral" (white) wire to complete the circit.


5% voltage drop is commonly allowed and is probably the root cause of the sloppy terminology.

Here are two links that explain it all:
Basic info:
http://www.cs.uu.nl/wais/html/na-dir/electrical-wiring/part1.html


Fred

 

[frank_f15]

Re: 220 volts/230 volts/ 240 volts: What\'s the diff?

not being an expert on such matters, they are basically the same. u will see a lot of thing listed as 110/120 or 220/240. i do beleive most electric servises allow a 5% or 10% varience in the voltage.

 

[Ches]

Re: 220 volts/230 volts/ 240 volts: What\'s the diff?

Bird, Frank, Fred;
Thanks for the reply and answer to my question. I sort of thought they were actually the same, and had even thought they were called different voltages depending on where one might live, or maybe was related as to how old a service might be.

 

[Bird]

Re: 220 volts/230 volts/ 240 volts: What\'s the diff?

Having spent a considerable amount of time traveling in RVs, I learned early on to carry my own test equipment to check the electric power in RV parks before plugging into it. Unfortunately, a lot of RV park owners are NOT electricians and sometimes do some funny things with their circuits. As you probably know, polarity is not a concern with some electric powered equipment, but it can seriously damage others. In my travels, I can remember two RV parks (one in Arizona and one in Oregon) with 30 amp receptacles with reversed polarity (the managers in both parks had no idea what I was talking about, but I showed them and corrected it myself), one park (in Indiana) only had 105 volts (pretty risky if you want to run an RV air-conditioner), one park (in Pennsylvania) said they had 30 amp service. (turned out they had 30 amp receptacles and 20 amp breakers (when I showed them why the breakers kept kicking off they called an electrician to correct the problem the next day)./w3tcompact/icons/laugh.gif

And where there are no building codes and people can do whatever they want . . ., it's sometimes hard to believe what some folks have done./w3tcompact/icons/shocked.gif When I bought my little 10 acre farm, there was an old ragged mobile home on it. There was a 100 amp master panel on the pole just below the meter; a single 100 amp breaker in it. They had run wires from that to the 100 amp panel in the trailer, another wire from that 100 amp breaker on the pole directly to an electric water heater in the trailer (they had replaced a gas water heater with an electric one), and another wire around the house, from the same 100 amp master breaker, into a 200 amp panel in the shop building, then wired from a 30 amp breaker in that 200 amp panel to a 60 amp panel in the barn (wire from the shop to the barn buried about 3" deep in PVC conduit that was full of water and they had spliced the wire by just twisting the ends together so the splice was in water and the breaker in the shop would kick immediately if you tried to reset it)./w3tcompact/icons/laugh.gif I still wonder why the place hadn't burned down./w3tcompact/icons/laugh.gif Needless to say, I replaced everything myself.

 

[cowboydoc]

Re: 220 volts/230 volts/ 240 volts: What\'s the diff?

I know some equipment you have to have a voltage regulator for if it is specific as to the amount of the volts that it needs. There is a tanning bed place in my office building that I own and we had to install these on all of them as they had to have exactly the right amount of volts at all times.

 

[MDNick]

Re: 220 volts/230 volts/ 240 volts: What\'s the diff?

Sometimes you will need more than a voltage regulator as well. Buck/boost Transformers slightly step down or up voltages to give what is needed for a electrical device requiring precise voltages. These transformers can change the voltage by up to 21% (I think). After that it is officially a step up or down transformer, not a buck/boost. For most apps the minor variation between 220-240 doesn't matter, for some, well, they want it dead on want they want. The welder is not likely to care in the least.

Machine shop buddy of mine is running his entire shop off residential service 220V. He has 2 large lathes, a CNC turning center, CNC Mill, bridgeport manual mill, etc. They all want 220 3 phase, and the CNC's want precise voltage. He is running 2 rotary phase converters to get 3 phase (needed 2, one of the CNC's takes enough juice to require it's own), and was lucky that SMECO is providing good stable voltage at his required voltage.

I have a line on a small lathe, wants 440 or is it 460, or 480. 3 phase. What a pain. Can't beat the price on the lathe, though. The phase converters are extremely efficient, but don't handle electrical devices that start under load, like air compressors. If you want to know about rotary phase converters, I can explain it, but don't ask unless you really want to know!

 

[Hoeman00]

Re: 220 volts/230 volts/ 240 volts: What\'s the diff?

Just find me a good used 7.5hp rotary.
I need one for the shop.

Want to see the FIRE fly hook up 2 legs of
480 (277v/leg) to a 220v water heater.
One of the other maintenance workers did it.
Old half plant is 208 3 phase and new part is 480 3 phase.
He learned a VALUABLE lesson.
Always check w/ multimeter!

 

[Inspector507]

Re: 220 volts/230 volts/ 240 volts: What\'s the diff?

Ches,
Plug it in........you'll be fine. But I'm glad you had the sense to ask BEFORE you did. Hate to see it go poof..../w3tcompact/icons/grin.gif