Kilowatts per hour

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chevyx92

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VA BCH, VA
This may be real simple but how do you figure Kilowatts per hour? Theoretically if you have a load of 25KW, how would I figure kilowatts per hour with that number? Single phase service 120/240V.
 

Dennis Alwon

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Chapel Hill, NC
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Retired Electrical Contractor
chevyx92 said:
This may be real simple but how do you figure Kilowatts per hour? Theoretically if you have a load of 25KW, how would I figure kilowatts per hour with that number? Single phase service 120/240V.

If your load is 25 kw that means for every hour you would use 25kw.
 

Dennis Alwon

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Chapel Hill, NC
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chevyx92 said:
Thats a good link. I like the residential chart. Do you know of a commercial chart? Better yet Dennis, do you know the commercial rate (cents per kWh) in North Carolina, since that is the state in question of this project?

Chevy there are a few power companies right in the Triangle area where I am from--- Duke Energy, Progress Energy and Piedmont. Each one has different rates.... where is the project?
 

chevyx92

Senior Member
Location
VA BCH, VA
Dennis Alwon said:
Chevy there are a few power companies right in the Triangle area where I am from--- Duke Energy, Progress Energy and Piedmont. Each one has different rates.... where is the project?
Duke University(durham county).
 
L

Lxnxjxhx

Guest
A joule is a measure of energy and a watt is a measure of the rate of expending energy.

A watt is a unit of power equal to dissipating one joule of energy per second.

A power level of 25 kW maintained for one hour equals an amount of energy equal to 25 kWh.

Lifting 55 pounds 10 feet vertically expends 550 ft-lbs of energy. If you do this in 1 second you have generated an average of one horsepower (=746 watts) for that one second interval.

Energy and power are measured in different units and can really mess you up.
 

charlie b

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Location
Lockport, IL
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Retired Electrical Engineer
chevyx92 said:
. . . how do you figure Kilowatts per hour?
You don't. Ever. That particular combination of words has no practical meaning to our industry. It is however a commonly mis-used set of words.

To give you the answer you need, I would need to know the context in which the problem was presented to you. Did you, for example, mean to ask about kilowatt-hours? If so, the dash between "kilowatt" and "hours" is not read as if it were the word "per." We do not divide power by time. But if we multiply power (which itself is "energy divided by time) by time, the result is energy. KWH is a measure of energy.
 

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
chevyx92 said:
Do you know of a commercial chart? Better yet Dennis, do you know the commercial rate (cents per kWh) in North Carolina, since that is the state in question of this project?
POCO's are generally secretive about this. The link Dennis posted alluded to this but commercial customers are charged based on peak demand. I'm not sure of the exact formula in which this is billed but in laymens terms if your demand at peak intervals is say 50 KW you are billed at the 50KW rate (say $0.50/KW hour). If, at any point during peak usage times, you require 60 KW then you are billed at the 60 KW rate (say $0.60/KW hour) for the entire month or whatever interval the POCO decides. From my experience you can place as many phone calls as you wish to your local POCO but no one at the POCO will tell you what you want to know. If you end up being more successful at getting this info than I was would you please post your findings here ? Thanks.

Phil
 
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