110 or 220V's

[Plate plinker]

Nice analogy razorfish.

[NyFirefighter357]

The real advantage of 220V on large loads is circuit wiring. 20amps needs 12ga wire. If you needed 40 amps for 110v circuit you would need 4ga wire and an equally sized neutral, which is more expensive and harder to through the walls. By using 2-12ga for 220v wires you can divide the amperage between the 2 smaller wires and of course don't need a neutral. And as the lengths get longer the wire needs to be larger.

[Mal Paso]

The real advantage of 220V on large loads is circuit wiring. 20amps needs 12ga wire. If you needed 40 amps for 110v circuit you would need 4ga wire and an equally sized neutral, which is more expensive and harder to through the walls. By using 2-12ga for 220v wires you can divide the amperage between the 2 smaller wires and of course don't need a neutral. And as the lengths get longer the wire needs to be larger.

8 gauge wire. 40 amps requires 8 gauge wire.

[dragon813gt]

8 gauge wire. 40 amps requires 8 gauge wire.

Yep, #4 will handle 70-95A depending on the wire type used.

[mvozz]

I think most of you have overlooked the MOST important reason to get 220V equipment of any kind - Lead pots, air compressors saws etc..... It makes it harder for other people to borrow it from you!!!

[dragon813gt]

I think most of you have overlooked the MOST important reason to get 220V equipment of any kind - Lead pots, air compressors saws etc..... It makes it harder for other people to borrow it from you!!!

Three phases fixes that problem permanently

[alamogunr]

I guess I'm a little out of my depth here. I always thought that 3 phase was an advantage in large electric motors, primarily in an industrial environment. Does it even work for resistive loads?

[dragon813gt]

Yes, it works in resistive loads. Amp draw is lower just like in motors.

[Catshooter]

alamogunr,

Yes, that's right. Electric heat is a resistive load so it starts gently and ramps up to full load. A motor is an inductive load and starts with violence (often six time the running current) and then tapers off to running load. In industrial environments there are engineering considerations that can make sense for using a three phase circuit for a heating load but power consumption isn't one of them.

As an example, the largest heat load I've ever seen is in a glass furnace. The furnace itself was square so they installed a four-phase 180/276 volt set up. One phase in each corner, arcing over to the other corner through the molten glass kept the glass liquid. Drew well over 10,000 amps. Since the furnace was square they needed four phases to arc over to each other. Made an X I suppose though of course you couldn't see it. If it had been triangular three would have been the way to go.

The poster with the pushing the car up the hill is actually a good analogy, but it only works for inductive loads as described above. Doesn't work for a heat (resistive) loads. Electricity is tricky stuff!


Cat

[alamogunr]

That is interesting. I retired from a factory that made conductors for amperage well over 10,000 amps but I never saw the actual application. I wouldn't be surprised if some of those products were used in that glass furnace.

[gwpercle]

No it doesn't. Watts are watts. 10 amps at 110 volts is 1100 watts. 5 amps at 220 volts is 1100 watts. There are lots of reasons for using 220 over 110. Reduced power consumption is not one of them.

You got that right ! Reduced power consumption is a misconception.

[Boogedy_Man]

My definition of using single phase against multiple phase, is that it is easier for two or three people to push a car up a hill than one large man to do the same thing.

240 is still a single phase in nearly all residential applications.

[Boogedy_Man]

The real advantage of 220V on large loads is circuit wiring. 20amps needs 12ga wire. If you needed 40 amps for 110v circuit you would need 4ga wire and an equally sized neutral, which is more expensive and harder to through the walls. By using 2-12ga for 220v wires you can divide the amperage between the 2 smaller wires and of course don't need a neutral. And as the lengths get longer the wire needs to be larger.

Some applications may still require a neutral....like ranges, dryers, etc...because there's still an unbalanced load.

The most conservative rating for allowable capacities in copper conductors (60 degrees C) puts 8awg at 40 amps, and 4awg at 70. Of course, there are situations where this would need to be derated, and other situations (such as welders) where smaller conductors could be used due to low duty cycle.

[Boogedy_Man]

alamogunr,

The furnace itself was square so they installed a four-phase 180/276 volt set up. One phase in each corner, arcing over to the other corner through the molten glass kept the glass liquid. Drew well over 10,000 amps. Since the furnace was square they needed four phases to arc over to each other. Made an X I suppose though of course you couldn't see it. If it had been triangular three would have been the way to go.

That's a polyphase setup I'd like to see...how was this power generated?

[Boogedy_Man]

Looking to buy a melting pot. Lot's of model come in either 110V or 220V. I have 220V readily available in my garage. What the benefit of one over the other?

OP...there could be a huge advantage depending on which code your home was built under, and how the electricians decided to design it.

In this area it is very common for homes to have a single 15A circuit for all garage receptacles and all required outdoor GFCIs...which in my opinion is an absolute disaster.

The 2014 code changed that practice, but many jurisdictions are still on much older code. I'm not up to speed on the 2017 code, but I believe there may have been even more conservative rules resulting from the popularity of electric cars.

The shorter answer is what you've already heard....if you have a 120V circuit that you can use without overburdening...there is no advantage.

[Boogedy_Man]

This discussion is all single phase 120/240 volt. A 20 amp 120v circuit max is 2400 watts, the recommended safe load is 80% or 1920 watts. 1440 watts for 15 amps. My old pot was 700 watts and the hot plate 1500 so I ran an extension cord from another circuit...

The 80% rule is for a single piece of cord and plug connected equipment that is not fastened in place. You can safely use 100% of a multiple outlet branch circuit, unless any portion of the load is a continuous load.

[Catshooter]

Boogedy Man,

The power was transformed. Three phase 26k incoming. The engineer called it two-phase! It was a very cool place to work in. Worked there three or four times over the years.

We were working underneath one of the furnaces one time that was running. Lots of steel support system and such. Man came in with us and put a Port a Band down on the ground. It had just had it's cord replaced. When he set it down the ground prong touched a steel support. The cord was still in a wrapped curl from the factory. Didn't take but about a couple of minutes and the cord was smoking. We slapped an Amprobe on it and the ground was drawing nearly 40 amps! Just a few loose killywiggles about.

The power to the furnace was run around three sides of the furnace in bussing. Two parallel runs of one inch by twelve inch aluminum plate, un-insulated. The busing was about eight feet up so you kinda wanted to watch were you were swinging a stick of conduit!


Cat

[sharps4590]

Cast, I've been an electrician for 42 years, passed my Masters Exam in '81. I would be tickled to death to see that furnace you're talking about. Certainly nothing like that around here unless something similar might be at MS&T in one of their labs. They do have some cool toys!

[Boogedy_Man]

Catshooter, that's pretty dang cool.

[Catshooter]

I'm a retired union wireman, worked in Seattle. Some pretty cool installations there.

I worked at Boeing's wind tunnel site quite a bit. Four point three acres, they had over 80,000 horsepower in electric motors. One was 55,000.

Their air compressor building has a 6,000 horse primary compressor. When they put it in in '64 is was a 5,000, but that was too small so they pulled it and had it re-wound to six. 4160 volt, across-the-line start! When that starter closed it sounded like a .30-06. In a quarter of a cycle it went from zero to over 3,000 amps. The operator told me that if the incoming voltage was less than 4.2, he'd call Seattle City Light and ask them to raise it. The motor would almost start at that voltage. If it failed he couldn't try again for eight hours so it could cool.

We replaced the 4 MVA transformer that fed that motor with a new 12.5 MVA unit. It weighed 1/3 of the old one.

Saw and worked on some cool stuff there.


Cat