Stray Voltage and Power bill

Status
Not open for further replies.
Two unit house. Circa 1950. Two separate electric meters. FPE breakers. One larger unit and one smaller unit. The smaller units electric bill is much larger (~ $100) than the large units bill. Small units tenant is seeking reimbursement for large power bill.
 
110826-1116 EDT

mphillipps:

Assuming a rotating disk kWh meter:
1. Turn every thing off in the house.
2. Disk should be perfectly still.
3. Turn one circuit on that has no load.
4. Disk should still be perfectly still.
5. Connect a 100 W 120 V incandescent bulb to the circuit. At 120 V this probably will be within +/-2% of 100 W.
6. Time exactly one revolution of the disk.
7. Determine the meter calibration constant, and calculate if it is working reasonably correctly based on the 100 W bulb load.

Assuming the meter is OK, then sell a TED 1000 series whole house monitor system to the customer. Then have the customer with your help analyze their consumption. You should order the in-line filter and Footprints software to go with the 1000 system. Note there are some problems if the customer is supplied from a three phase source.

Do not get a series 5000 system it possibly has major bug problems.

.
 
Another check to make is to verify disk (if applicable) does not freewheel.

It should stop immediately once a load is turned off. Check by turning on a large load, like a stove burner, and watch the disk as the load is turned off. This will take two people and maybe a couple radios.
 
mphillipps said:
Two unit house. Circa 1950. Two separate electric meters. FPE breakers. One larger unit and one smaller unit. The smaller units electric bill is much larger (~ $100) than the large units bill. Small units tenant is seeking reimbursement for large power bill.
Click to expand...

Are there the same amount of people in each unit?

Three people in the small unit will have a much higher bill than one person in the larger unit.
 
gar said:
110826-1116 EDT

mphillipps:

Assuming a rotating disk kWh meter:
1. Turn every thing off in the house.
2. Disk should be perfectly still.
3. Turn one circuit on that has no load.
4. Disk should still be perfectly still.
5. Connect a 100 W 120 V incandescent bulb to the circuit. At 120 V this probably will be within +/-2% of 100 W.
6. Time exactly one revolution of the disk.
7. Determine the meter calibration constant, and calculate if it is working reasonably correctly based on the 100 W bulb load.

Assuming the meter is OK, then sell a TED 1000 series whole house monitor system to the customer. Then have the customer with your help analyze their consumption. You should order the in-line filter and Footprints software to go with the 1000 system. Note there are some problems if the customer is supplied from a three phase source.

Do not get a series 5000 system it possibly has major bug problems.

.
Click to expand...


There should be a 'KH' rating on the meter. Standard is 7.2, so you would see 'KH 7.2' somewhere on the meter.

Then use the formula P= (3600 x kh) / t, where t = time in seconds.

So, a calibrated 100 w load would be 100 = (3600 x kh) / t. Using 7.2 for kh, we get 100 = 25920 / t, or one disk rotation in 25.92 seconds.

I would not assume a bulb marked 100 watts will be an exact 100 watt load. At the least, a device like a Kill-a-Watt should be used to verify that there is a 100 watt load. If not, just use whatever load the Kill-a-Watt shows for P and do the math as above.

ON EDIT: I just checked a 100 watt 120 volt Sylvania bulb. It read 95 to 95.4 watts. The voltage was 118.0. That same bulb in a 120 volt house may draw a full 100 watts.

I just wanted to put this in to clarify 'calibrated load'. The only way to 'calibrate' a load in watts is to know the exact voltage it will be used on.

My 100 watt bulb would actually take 27.84 seconds for a spin on an accurate meter, not 25.92
 
Last edited:
Another thing I thought of.....probably not likely......but.......

What if the unit with the small bill is fed off the load side of the meter with the large bill?

A hundred dollar difference in bills that 'should be' close to the same is more than I would expect just based on a difference of usage.

I think this has been mentioned, but try shutting off the main on the unit with the large bills and see if the meter quits, or runs at the same speed as the meter that shows the smaller bills.
 
Drop by unannounced next week a couple times throughout the day and check the amperage on the two units. Betcha the smaller unit runs the A/C more. :happyyes:
 
George Stolz said:
Drop by unannounced next week a couple times throughout the day and check the amperage on the two units. Betcha the smaller unit runs the A/C more. :happyyes:
Click to expand...

Good idea, George. Is the smaller unit on the second floor? My upstairs AC works a lot more than my main level AC and is sized accordingly.
 
If everything else checks out, I would also suspect that at some time, someone tapped into some wires and has/had been stealing power from the other unit. I've seen that twice on small industrial complexes where there were pot farmers next door. The police look at power bills for supposedly unoccupied units as a way to track them down, so they cut into the neighbor's lines to power the grow lights. In a rental unit with a high turnover, it may have happened a long time ago and nobody has noticed before.

Aside from that, my son and daughter live in the same appt. complex, my son's unit is on the 2nd floor, daughter's is on the first directly below him. She does a lot of baking and she likes the appt. toasty warm even in the summer. My son likes it cool. He has to run his AC unit almost night and day to make up for the heat that comes up from her appt, she almost never turns her AC on. His electric bill is almost 3X what hers is in the summer, same size appt. Conversely he spends almost nothing for gas in the winter time, her unit heats his.
 
Status
Not open for further replies.
Top