Settle argument

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toddro1971

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My supervisor and I disagree on a particular subject. Simply put, he states that by changing our existing plant lighting circuit from 120 volt to 240 volts we will save on our power bill. He says that since the voltage at the meter is constant and by lowering the amperage drawl we will consume less power and therefore lower our electrical bill.

I say our power bill is based on wattage which is a product of voltage times amperage and therefore will not save us any money.
 
Re: Settle argument

Originally posted by toddro1971:
My supervisor and I disagree on a particular subject. Simply put, he states that by changing our existing plant lighting circuit from 120 volt to 240 volts we will save on our power bill.
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You are correct it will be the same wattage which is a measurement of power and what spins the meter.

Lighting that draws 10 amps at 120 volt will draw 5 amps at 240 volt.

Either way it is 1,200 watts.

10 * 120 = 1200

5 * 240 = 1200

Remind him that the bill is based on the Kilowatt hour, not the amp-hour. :p
 
Re: Settle argument

Here is your chance to move up.Show him up for what he is and you should be either one of 2 things.Either let go because you know more than him ,or take his job.While this kind of misunderstanding is understandable from a non electrician ,it is showing his ability if he is the electrician over you.Dang i am converting every thing in my house to 240 and cutting bill in half :D :D
 
Re: Settle argument

Supervisor: With your calculations, you are correct. However, when you change from a lower voltage to a higher voltage you will not necessarily have a 50% drop in amperage. Your current usage will normally drop below the 50% mark, therefore using less current, therefore using less wattage.
Example one:
2 hp motor at 110 volts (pool pump motor)

2 hp motor at 220 volts (newer pool pump motor that has a higher efficency rating)
Example two:
Multi-tap ballast on 110 volt line

Same Multi-tap ballast on 220 volt line but drawls less current drawl equals less wattage used.
 
Re: Settle argument

Originally posted by toddro1971:

Example one:
2 hp motor at 110 volts (pool pump motor)

2 hp motor at 220 volts (newer pool pump motor that has a higher efficiency rating)
Click to expand...
toddro1971 that is not an example as you are comparing two different items, an old motor vs a new motor.


Originally posted by toddro1971:
Example two:
Multi-tap ballast on 110 volt line

Same Multi-tap ballast on 220 volt line but drawls less current drawl equals less wattage used.
Click to expand...
Can you explain that one?

Here are the specifications for a 400 watt metal halide ballast

4 amps at 120 volt = 480 watts

2.3 amps at 208 volt = 478 watts

2 amps at 240 volt = 480 watts

1.73 amps at 277 volt = 479 watts

No gains of efficiency based on this ballast.

However, if the building has a 480 volt service it is a gain of efficiency to run the ballast at 277 or 480 so losses at a transformer are reduced. :)
 
Re: Settle argument

There is some truth to what he says, but in general it is not especially significant.

Higher voltage items that have the same wattage will draw less current, so the I^2R losses in the wiring are less, IF you have the same wire size.

You might make an arguement that using #12 wire in lieu of #14 would result in an energy savings too.

Look at a 15A circuit @ 120V run for 100 feet. Thats .628 ohms @ #14 and only .396 ohms @ #12. You would dissipate 141W in your wiring for the #14, and 89W in the #12. Thats a 52W savings, or about 1.25 kW-hr per day. Thats $45 a year @ 10 cents/kwhr.

Of course during heating season the wire heating reduces your heat bill some, but in AC season you have to pay extra to remove that heat.
 
Re: Settle argument

Supervisor: (This is Mike, not Todd) My discussion with Todd was in trying to make the point that if I have a device with a greater efficency (using less than 50% of the current at twice the voltage, then I will have used less wattage at the meter. The question and answers from each of you are correct that there is no difference in money spent if a change in voltages does not create a better than 50% reduction in current (i.e... the example with the older and newer motor). Here's where my ignorance may be showing (and no I'm not an electrican), if the ballast used less than half of the current at a higher voltage then we pay less. The math shown by the first response wasn't representative of our conversation and I didn't explain myself as well as I should have in the initial question.

Todds comment: Right, but in this case were not going to a higher efficency device. We are just changing the voltage on the same device.

Mikes comment: (By the existing lighting device we are using, Todd is correct) (By my statement on a device with better efficency, I believe I would be correct.)
 
Re: Settle argument

I agree Bob, but in general if the amperage is lower smaller conductors are used so the heat losses will remain about the same.

We are talking about doubling the voltage and cutting the current in half. Very doubtful the conductors length or size would remain the same.

The conductor would be smaller diameter or a longer total length.
 
Re: Settle argument

toddro - your supervisor does not seem to know what he is talking about, as evidenced by the comments from iwire & jimwalker.

That's one of those old myths usually quoted by non-electrical people.
Another one is - "a white wire can never hurt you".
 
Re: Settle argument

Originally posted by kiloamp7:
That's one of those old myths usually quoted by non-electrical people.
Another one is - "a white wire can never hurt you".
Click to expand...
OUCH!

Yeah them there white wires can't hurt ya none. :D
 
Re: Settle argument

Originally posted by toddro1971:
Supervisor: (This is Mike, not Todd) My discussion with Todd was in trying to make the point that if I have a device with a greater efficency (using less than 50% of the current at twice the voltage, then I will have used less wattage at the meter. The question and answers from each of you are correct that there is no difference in money spent if a change in voltages does not create a better than 50% reduction in current (i.e... the example with the older and newer motor). Here's where my ignorance may be showing (and no I'm not an electrican), if the ballast used less than half of the current at a higher voltage then we pay less. The math shown by the first response wasn't representative of our conversation and I didn't explain myself as well as I should have in the initial question.

Todds comment: Right, but in this case were not going to a higher efficency device. We are just changing the voltage on the same device.

Mikes comment: (By the existing lighting device we are using, Todd is correct) (By my statement on a device with better efficency, I believe I would be correct.)
Click to expand...
Is Mike sitting on Todd's lap, or vice versa? :D

Somebody needs some money for their own computer... :D :D
 
Re: Settle argument

Do I understand multitap ballasts correctly? It seems that higher line voltages means more drop across the ballast which means more iron loss and more windings on the same core means more copper loss. Ballasts are not 100% efficient.
 
Re: Settle argument

Going to a high voltage only saves you installation cost. The power consumption is the same.
 
Re: Settle argument

toddro1971,

I would have to agree that for all practical purposes, the electrical bill would remain unchanged. Supervisor is now scratching with his argument that higher efficiency motors etc. would save. While to some minute extent this may be true, the amount of savings would be more or less insignificant. Higher voltage may not always translate into higher efficiency across the board. What about the cost of converting everything to a 240v system? How long would it take to realize such a small, if any, savings in operating cost?

Bob
 
Re: Settle argument

Bottom line is that he is the boss, you are the employee. Some arguments are not worth loosing your job for. Agree with him, do it his way, when he is wrong, simply state that you did what you were told to do because you get paid to listen to the boss.
 
Re: Settle argument

I'm not getting the impression that this is a heated argument between these two gentlemen. It seems more as a matter of fact discussion and Todd is not at risk of losing his job over this. I don't think Mike is being unreasonably hard-nosed about this either because he has not yet been proven entirely incorrect, insignificant though it may be.

Bob
 
Re: Settle argument

The savings would be very small compared to the cost of changing the system from 120 V to 240 V. I wouldn't even know how to calculate the savings one would achieve, if any. But it would be easy to calculate how much it would cost to change from 120 V to 240 V system. Most energy savings programs I have dealt with try to get a simple payback of 10 years at the most, and usually around 3-5 years. Simple payback period being how long it would take for the savings to pay for the installation cost, or in this case the changeover cost. And in this case I think the simple payback would be much greater than 10 years. :D
 
Re: Settle argument

If you really want to cut you electric bill and get some payback: </font>
  • <font size="2" face="Verdana, Helvetica, sans-serif">Install point of use small water heaters</font>
  • <font size="2" face="Verdana, Helvetica, sans-serif">Install flow restrictors in the water lines</font>
  • <font size="2" face="Verdana, Helvetica, sans-serif">Replace all incandescent lamps with self ballasted ones or HID fixtures</font>
  • <font size="2" face="Verdana, Helvetica, sans-serif">Caulk</font>
  • <font size="2" face="Verdana, Helvetica, sans-serif">Install more insulation</font>
  • <font size="2" face="Verdana, Helvetica, sans-serif">Etc.</font>
<font size="2" face="Verdana, Helvetica, sans-serif">I know, a lot of the things on the list only applies to electric savings if the building is total electric but they work anyway.
 
Re: Settle argument

Charlie, I guess I'm going to get blasted for this but are meters actually sensitive enough to discount for unbalanced loads in single phase applications. I thought 220 was more efficient (in terms of metering) than unbalanced loads.

paul
 
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