Cost difference of running electric 120v or 220v melting pot

[Lloyd Smale]

correct answer

Common misconception says 220 AC "costs less to use" but a watt IS a watt and we pay for watts per hour. All a higher line voltage accomplishes is a reduction in the needed wire size to feed a certain load. Thus, if a 110 circuit has sufficent current carrying capacity (and most do) it won't matter a bit. It's hard to justify installing a dedicated 220 line for a device that won't reduce operating costs at all. IMHO.

[sharps4590]

correct answer

Watts
---------------
Amps X Volts


Mix it up any way you want and you can calculate any factor you need. Until you get to 3 phase, then it changes, well, the voltage number will change but not the formula. No need to get into that here.

[BD]

In theory I accept that a watt is a watt. In practice, I am not convinced. I am not an electrician, and am speaking only from my own experience. I have found that dual voltage motors cost less to run under load over time when wired 220, rather than 110, and that this difference becomes more noticeable as the ambient temperature goes down. I make this observation from years of experience with tablesaws/radial arm saws/planers, and fleshing machines, all in production shop environments. In all cases the motors are started and almost immediately loaded to the max they will take, then shut off as soon as the load is removed. When wired 110, the motors start much slower, (especially when very cold), throw the overheat reset much more frequently under heavy load, and result in a noticeably higher monthly electric bill in the shop.

I have twice converted shops to higher voltage as much as was possible, and in both cases experienced a lower electric bill as a result, along with increased production. I have no idea how this experience would relate to lead melting pots.

The other relevant issue is voltage drop over line length. All of the big portable saws on our projects are wired 220. They just plain "won't cut it" on 110 when run at the end of 100 feet of 12 guage SO cord , and if you went to 10 guage no one would be able to lift the cord out of the truck.
BD

[Catshooter]

BD,

I am an electrician, more than 34 years worth. And I'm here to tell you that there are things we know about electricity and there are things we only think we know.

I beleive your experience because having read enough of your posts over the years I know you to be an intelligent person capable of observing what's in front of him.

Voltage and amperage are tied together, if you raise one you lower the other. When a motor starts it will draw up to about six times it's running load for a short time while spooling up. If you start a motor at 110 volts it will draw a certain amount of watts to do so. If you then wire it to run off of 220 it will take half as much wattage to get it rolling. I bet in the production environment you're discussing you did see much improvement when going to the higher voltages. Frequent starting is very hard on motors.

This surge during start up doesn't apply to the type of electrical load that a lead pot goes through. When it starts, it starts and it doesn't draw more to do so. In fact I believe it ramps up to full load, rather the opposite of a motor. We use Nichrome wire for heating elements and as they heat up their resistance increases until it stabilizes.

Electricity is weird stuff. Anyone who claims to understand it all is a fool. One of the first sentences in the American Electricians Handbook is that we really don't know what electricity is. The theories about it are just that, theory. Fancy guesses that may work. Twice in my career I've seen electricity do "impossibe" things. Flew straight in the face of current theory.

Voltage drop over cords is a very real problem and what you say is total fact. I measured a heavy duty skilsaw's start up amperage once, it was over 65 amps. When you try to do that at the end of a 100 foot 12 gauge cord the voltage drops waaaaaay down, forcing the amps even higher to the point where there just isn't enough volts to cause the motor to spin.

In theory, theory and practice are the same. In practice, they most definatley are not. A lot of engineers forget that.


Cat

[454PB]

Agreed.

All conductors have resistance, and the longer the wire, the more resistance.

While I still worked in power generation, we saw examples of this all the time. String out 300' of #12 wire and apply 120 volts to one end, measure at the other end and you'll see very little voltage drop. Now add a load, and you'll see a lot of voltage drop, sometimes to the point where the electrical device won't even operate or will begin to heat.

That doesn't mean the wattage has changed, it means you have introduced additional resistance via the long conductor. It's the reason power transmission lines utilize high voltage through small conductors to move electrons from the source to the load, then use transformers to reduce the voltage and raise the amperage.

[popper]

No advantage to a 220 pot at all, unless you are a commercial operation.

[MrXrings]

I have one of those kill=a=watt meters in my shop and plugged my pot into it a it ran for about an hour, currently we pay about 10cents per kwh here and it showed 4 cents of power used so that would take into account the warm up and the cycling once the pot was to temp. Cheaper than I thought too. Power is power makes no difference 220 or 120v. Watts equals voltage times current, you double the voltage and it cuts the current in half and vice versa, there is no free lunch.

[41mag]

Well I can honestly tell you that when after pouring several times a week for a month or so when I started I didn't hardly notice any change what so ever in my bill. When my nephew moved in with us in order to be close to the job he landed, I noted it went up an extra 50-75 bucks.

After that I had a REAL good conversation with him about leaving lights on, and doors open, when he was either out of the room or outside smoking. After the little get together, the bill has now dropped back into the same general area it had been.

No telling how much I have saved over the years since my daughter has moved out, but it has probably all been spent up on reloading or casting accessories.

[yobohadi]

Lets forget about a long length of wire to deliver the power and pretend your outlets are just a few feet from your Main breaker and you measure 110 Volts and 220 Volts at your outlets...

Watts = Volts X Amps

A 700 Watt Element run on 110 Volts will use ~6.36 Amps.

A 700 Watt Element run on 220 Volts will use ~3.19 Amps.

They will both use the same Watts the only difference really will be that you can run 3 pots on a 110V 20Amp circuit.

Whereas you can run 6 pots on a 220Volt 20Amp circuit.

So the only cost difference is 3 more 220 Volt pots.

[alamogunr]

I saved $$ with a 220V(230V?) pot. A few years ago, Midway had a clearance on RCBS ProMelt 220V pots. I saved about $50-75. I already had a 220V outlet in the shot for my table saw so I cut off the European plug and wired the same plug as the saw used on the pot. The HVAC unit in the shop uses way more electricity than either the ProMelt or the Lee Pro 4-20.