Get peak load from utility bill

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dahualin

Senior Member
I am doing load evaluation for my client. They have sent me recent 12 months utility bills that shows total KWH used, OFF peak KWH used, Interm peak KWH used, and On peak KWH used. Since I don't know how many hours it is on peak load, I cannot use the On peak KWH divided by the hours on peak to find the load. I remember this topic had been discussed before, but I cannot find it.

Any help is really appreciated.

David
 
J

jtester

Senior Member
Location
Las Cruces N.M.
Unless your "on-peak KWH" period was an hour or less, you could do a terrible disservice to yourself and your client by calculating demand with your approach. It is not uncommon for on-peak times to be 8 hours per day or more depending on the utility.

It would be relatively meaningless to divide a monthly reading that was an accululation of KWH consumptions by the # of hours in that portion of the month.

When taking this approach, I usually need KVA demand to make a reasonable judgement about load and spare capacity.

Jim T
 
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dahualin

Senior Member
Our client wants to put an addition to the existing building. So they want to know the existing electrical loads.
 
steve66

steve66

Senior Member
Location
Illinois
Occupation
Engineer
If the utility has installed a "demand" meter, they may have the peak load measured over a 15 min. period on record. I don't think they put that on the bill though. You will probably have to call customer service. I usually have to have the client call. They won't talk to me about anything until the customer gives them the OK.

Steve
 
bob

bob

Senior Member
Location
Alabama
The only way you can get that information is if the utility is billing the customer a peak demand charge. If not all they will bill is for kwh which will
not tell you the information you need. There are clip on meters available to
measure demand. Google search will provide you with mfg of there meters.
 
D

dahualin

Senior Member
I have just reviewed the utility bills again. I found a statement summary page that is separated from the other bills. The statement summary shows the number of days, total KWH, On Peak KWH, INT Peak KWH, Off Peak KWH, KW-Max, and KW-On-Peak for each month of the past 12 months. I try to find the On-Peak hours for each day based on the summary sheet. Unfortunately, it varied from 2 to 5 hours/day. What I did is the formula of On-peak KWH/KW-On-Peak/the number of days. Am I right?
I remember that some experts say always to multiply the peak load with factor 1.25 as existing load. Does anybody know the reason? Or it is experience. Thanks.

David
 
charlie b

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Retired Electrical Engineer
You are making this too hard, and you are trying to take deductions where deductions are not available. What you do is:
  • Ignore all mention of KWH.
  • Find the highest single value of kW seen at any time during the year.
  • Ignore any information that tells the length of time the demand was at that peak value.
  • Multiply that peak value times 125%.
  • Add the proposed new load.
  • Compare the result against the existing service/feeder rating.
And the most important thing to do is:
  • Don't believe me. Read 220.87 for yourself.
 
steve66

steve66

Senior Member
Location
Illinois
Occupation
Engineer
bob said:
The only way you can get that information is if the utility is billing the customer a peak demand charge. If not all they will bill is for kwh which will
not tell you the information you need. There are clip on meters available to
measure demand. Google search will provide you with mfg of there meters.
Click to expand...


I think the POCO may have that info. regardless of how they bill or what they put on the bill. But someone would have to call and find out.

The clip on meters won't do any good unless you have a year to wait per 220.87.

Steve
 
bob

bob

Senior Member
Location
Alabama
steve66 said:
I think the POCO may have that info. regardless of how they bill or what they put on the bill. But someone would have to call and find out.The clip on meters won't do any good unless you have a year to wait per 220.87.

Steve
Click to expand...
Steve
I was with Soutnern Co. for while. The only customers that were billed a kw demand were small commercial and industrial. The customer had to have a
certain minimum demand to be billed in kw and it changed to KVA at about 800 kw. Other utilities may do it differently.
As far as the 1 year wating time the exception will allow a 30 day period but done at peak load time.
 
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