Electrical Metering for Linemen and Techicians


Single Phase 120V 2 Wire - FM2S (Alternate 2)


(Form 2S Meter)


Form 1S meters are not required as often as form 2S meters. This metering diagram allows the more popular form 2S meter to accurately meter a 120V 2 wire service. Connect the meter as you would for a normal 3 wire 120/240V single phase service. Use either of the 120V connections available at the bottom of the meter along with the neutral to provide the required 2 wire 120V service. Mathematically, the 240V potential coil and one of the half-current coils from the 2S meter are equivalent to the 120V potential coil and a full current coil contained in the form 1S 120V meter.

Key Points for Metering:

  1. Notice that 3 wire 240 volt service must be wired to the top of the meter to provide the required 240 volts to the meter's potential coil.  Older existing 2 wire services may use SE cable from the utility service to the meter. The lack of suitable conduit coming to the meter may make it difficult to use this alternate connection.

Common Mistakes:

  1. Installing the form 2S 240V meter in a meter socket wired for a form 1S meter will usually result in a loss of revenue. Revenue is lost when one of the current coils is inadvertently bypassed through an earth ground.