Harris Institute of Technical Training

What happen if install form 2S meter into a 120 volts service?

Thanks Leang for the question regarding installing a Form 2S meter into a 120 volt, 2 wire metered service connection. This is a metering practice that can be done and there is a supporting connection diagram in both the 9th and 10th editions of the Meterman’s Handbook for doing this (see Figure 12-14, pg. 378 in the 9th and 12-19, pg. 421 in the 10th edition).
From the diagram, the connection includes a jumper across the two meter terminals on the load side which will put the meter current coils in series. The meter potential coil will need a special connection (shown in both Figures) at the potential clip so that it is energized at the correct voltage.
Also, the Form 2S meter will need to be an auto-ranging meter for it to meter correctly and for the electronics in the meter to work with the above connection. If it is an electromechanical meter then the meter potential coil is rated at 240 volts and this connection will only put 120 volts on it which will cause a metering error. You can test the meter at 120 volts to see how it will operate at this lower voltage and adjust the meter to the correct accuracy during this test.
Please let me know if you have any additional questions.
Thanks and Be Safe All Ways,
Brad