sid
Member
- Location
- Connecticut
Can some one tell me which section in the NEC talks about the ability of using previous electric bills as reference in calculating the servie..
Load based on utility bill
- Thread starter sid
- Start date
- Status
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: Load based on utility bill
220.35
220.35
Re: Load based on utility bill
Article 220.35, but I think it only applies if the electric meter is a "demand" meter. A demand meter displays the electricity used in Kilowatt Hours, and it also displays the peak demand in Kilowatts (which is usually averaged over a 15 minuite period).
Steve
Article 220.35, but I think it only applies if the electric meter is a "demand" meter. A demand meter displays the electricity used in Kilowatt Hours, and it also displays the peak demand in Kilowatts (which is usually averaged over a 15 minuite period).
Steve
charlie
Senior Member
- Location
- Indianapolis
Re: Load based on utility bill
This is what Bennie is talking about. This method will work on any meter, including a primary meter.
1. Look at the meter for a Kh (secondary watt-hour constant) number, this is the meter constant and indicates the energy used by the load for each revolution of the disk. If you are looking at a CT cabinet, someone will have marked a multiplier and is used to increase the Kh value for the CT ratio.
2. Count the revolutions of the disk for one minute, if you want a little more accuracy, use a little more time.
3. Multiply the number of revolutions in one minute by the Kh, and then by 60. Divide the resultant by 1000.
Example:
You are at a service that has a meter with a Kh of 3.6 and time the turns at 68 revolutions per minute.
(68)(3.6)(60) / 1000 = 14.688 kW
If this is a single phase service, the load in amperes is
14.688 / 0.24 = 61.2 amperes
This is just an instant in time and is of no use for any kind of load study. However, it may prove useful if you want a quick approximation of the load.
This is what Bennie is talking about. This method will work on any meter, including a primary meter.
1. Look at the meter for a Kh (secondary watt-hour constant) number, this is the meter constant and indicates the energy used by the load for each revolution of the disk. If you are looking at a CT cabinet, someone will have marked a multiplier and is used to increase the Kh value for the CT ratio.
2. Count the revolutions of the disk for one minute, if you want a little more accuracy, use a little more time.
3. Multiply the number of revolutions in one minute by the Kh, and then by 60. Divide the resultant by 1000.
Example:
You are at a service that has a meter with a Kh of 3.6 and time the turns at 68 revolutions per minute.
(68)(3.6)(60) / 1000 = 14.688 kW
If this is a single phase service, the load in amperes is
14.688 / 0.24 = 61.2 amperes
This is just an instant in time and is of no use for any kind of load study. However, it may prove useful if you want a quick approximation of the load.
sid
Member
- Location
- Connecticut
Re: Load based on utility bill
Thanks, this really helped...
Thanks, this really helped...
goldstar
Senior Member
- Location
- New Jersey
- Occupation
- Electrical Contractor
Re: Load based on utility bill
Charlie,
Interesting calculation. I followed you up until you divided by 0.24. What does that number represent ?
Thanks,
Phil
Charlie,
Interesting calculation. I followed you up until you divided by 0.24. What does that number represent ?
Thanks,
Phil
luke warmwater
Senior Member
Re: Load based on utility bill
Phil,
14.688 is kW. so .24 is the equivelant of 240 as compared to watts.
Am I right Charlie?
Todd
Phil,
14.688 is kW. so .24 is the equivelant of 240 as compared to watts.
Am I right Charlie?
Todd
charlie
Senior Member
- Location
- Indianapolis
Re: Load based on utility bill
If this is a single phase service, the load in amperes is
kW is about the same as kVA so to convert kW, you have to remove the W or VA which is 240/1000.
14.688 / 0.24 = 61.2 amperes where 14.688 is kW and .24 is 240 volts divided by 1000.
I made an assumption that everyone knew what the units were, I appoligize.
[ August 27, 2003, 08:05 PM: Message edited by: charlie ]
If this is a single phase service, the load in amperes is
kW is about the same as kVA so to convert kW, you have to remove the W or VA which is 240/1000.
14.688 / 0.24 = 61.2 amperes where 14.688 is kW and .24 is 240 volts divided by 1000.
I made an assumption that everyone knew what the units were, I appoligize.
[ August 27, 2003, 08:05 PM: Message edited by: charlie ]
- Status