# Switching lighting from 480 to 277



## user4818 (Jan 15, 2009)

The lights use less power. The total bill will go down. Changing the voltage has nothing to do with power consumption, unless we are talking about operating a 240 volt heater on 208 volts. Then the power consumption will decrease


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## dronai (Apr 11, 2011)

I agree with them, a watt is a watt ! Voltage is irrelivant


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## erics37 (May 7, 2009)

Drew1485 said:


> They keep saying a watt is a watt. Since more power is being required to power the lights the electrical bill will in fact go up...correct??


They're right. You pay for watts.

10 amps at 240 volts or 20 amps at 120 volts is gonna look the same on the power bill.


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## McClary’s Electrical (Feb 21, 2009)

What does voltage have to do with kwhr calc?...


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## Drew1485 (Jun 9, 2009)

I understand but I don't get how if your running 10 400w mh at 120v the amp draw would be 33amps but if it's 10 400w fixtures at 480v it's only 8.3 amps. So what's the benefit to running any fixtures at 277 or 480? I don't get how that's not using more power. I was always told people run machines, equipment, lights etc at 480 cause it's less expensive.


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## user4818 (Jan 15, 2009)

Higher voltage means smaller circuit conductors, more VA per circuit and less voltage drop. That's why it's always preferable to run equipment at the highest voltage possible.


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## Jlarson (Jun 28, 2009)

Drew1485 said:


> I was always told people run machines, equipment, lights etc at 480 cause it's less expensive.


It is less expensive, from a wire size, conduit size, bla, bla, bla standpoint.


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## Drew1485 (Jun 9, 2009)

So as far as your overall electrical bill is concerned, running something at a higher voltage to reduce the amp draw, does absolutely nothing? I learned something today...


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## user4818 (Jan 15, 2009)

Drew1485 said:


> So as far as your overall electrical bill is concerned, running something at a higher voltage to reduce the amp draw, does absolutely nothing? I learned something today...


Are you familiar with Ohm's Law at all? If not, I strongly urge you to learn Ohm's Law and how to properly apply its principles. It will unlock the door of understanding the relationship of power, voltage, current and resistance.


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## nitro71 (Sep 17, 2009)

I would check loading on those circuits. Most contractors will load a circuit to capacity. Dropping to 277 volts may very well increase your loading over the circuit capacities. In addition don't forget conduit fill and pulling in neutrals. Watts is watts as you found out.


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## electricalperson (Jan 11, 2008)

Drew1485 said:


> So as far as your overall electrical bill is concerned, running something at a higher voltage to reduce the amp draw, does absolutely nothing? I learned something today...


power is always the same. lets say you have a machine that draws 12 amps at 240. hook it up to 120 it draws 24. P = I x E 12 x 240 = 2880watts

24 x 120 = 2880watts

the real savings is breaker size, wire size and conduit size


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## jwjrw (Jan 14, 2010)

nitro71 said:


> I would check loading on those circuits. Most contractors will load a circuit to capacity. Dropping to 277 volts may very well increase your loading over the circuit capacities. In addition don't forget conduit fill and pulling in neutrals. Watts is watts as you found out.



Those T-5's pull way less than MH fixtures. I agree the calculation is necessary but will probably be ok. Unless I mis read the op's post.


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## walkerj (May 13, 2007)

Amperage is not power, it is current. 
Watts is power. 
That is what you are billed on.

Sent from your mom's iPhone. She says hi.


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## Dennis Alwon (May 9, 2009)

Why can't you use a 120v motion sensor to a coil for the 480V lights????


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## 220/221 (Sep 25, 2007)

Dennis Alwon said:


> Why can't you use a 120v motion sensor to a coil for the 480V lights????


 
More parts and pieces to fail/maintain.

You _could_ do a lot of things but the most simple solution is often the best.


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## nitro71 (Sep 17, 2009)

Pretty sure each light gets a motion sensor.


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## kaboler (Dec 1, 2010)

Drew1485 said:


> . However, they are saying since you are billed in Kwh your actually wattage is going down (24,000 to 15,500 appx) I tried explaining that since your changing the voltage your amp draw will go up. They keep saying a watt is a watt.
> 
> 
> > Well, 1000w metal halide actually draw probably around 1200w each, because while you screw in a 1000w bulb, the ballast draws (I find) 20% or so. However, when you're dealing with flourescent fixtures that are labelled, they're usually labelled in watts including ballast loss.
> ...


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## frenchelectrican (Mar 15, 2007)

Dennis Alwon said:


> Why can't you use a 120v motion sensor to a coil for the 480V lights????


Ya thinking one way but let moi think the other way is use small transfomer to kick down from 480 to either 120 or 277 volts so the OP do not have to really mess around with the exsting conductors if they are still in good shape.

A simple .250 KW transfomer will handle it nice.

Merci,
Marc


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## freeagnt54 (Aug 6, 2008)

frenchelectrican said:


> Ya thinking one way but let moi think the other way is use small transfomer to kick down from 480 to either 120 or 277 volts so the OP do not have to really mess around with the exsting conductors if they are still in good shape.
> 
> A simple .250 KW transfomer will handle it nice.
> 
> ...


There's no need for a transformer, the u.s has 277/480 panels.


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## BBQ (Nov 16, 2010)

Dennis Alwon said:


> Why can't you use a 120v motion sensor to a coil for the 480V lights????


You could of course but cost is king with lighting retrofits.

I know that I have no room in my per unit pricing to donate a relay.

Oh, I should mention ....... I am betting there is a motion sensor on every light, not just one sensor for many lights.


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## jwjrw (Jan 14, 2010)

BBQ said:


> You could of course but cost is king with lighting retrofits.
> 
> I know that I have no room in my per unit pricing to donate a relay.
> 
> Oh, I should mention ....... I am betting there is a motion sensor on every light, not just one sensor for many lights.





Every new T-5 we have installed had it's own sensor. Warehouses are switching to them so the lights will shut off when no one is in that section to conserve energy.


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