CURRENT TRANFORMER METERING

Current transformers are used with instrument-rated meters, to meter single-phase services greater than 400 amps (320 amps continuous), and three-phase services greater than 200 amps. Smaller services use direct-connect metering.

The customer provides and installs all equipment beyond the point of delivery: meter sockets, cabinets and enclosures for the meter and CTs, connection lugs, conduit, grounding, protection equipment, and wiring from the load to the CT mounting base.

The power company provides and installs the meter, current transformers, test switch, and local wiring associated with the meter, test switch, and CTs.

Services Metered Using Current Transformers
Services metered using instrument-rated meters and current stransformers are shown here.

Single-Phase, 120/240V 3-Wire Three-Phase, 277/480V 4-Wire Wye

Three-Phase, 120/208V 4-Wire Wye Three-Phase, 120/240V 4-Wire Delta

For more information:
Current Transformer Cabinet
Mounting Base for CTs, Single-Phase Services
Mounting Base for CTs, Three-Phase Services
Switchboard Metering