Metering Cheat Sheet

The Electricity Metering Cheat Sheet is a guide that assists electricians in matching the most appropriate meter form to a system configuration along with the appropriate wiring diagrams. The wiring diagrams can be explored for various meter forms and system configurations. All the wiring diagrams associated with a meter form or a system configuration can be viewed or, alternatively, only those that provide Blondel solutions.

It is great reference for engineers, technicians and electricians.

The system configurations are 2-wire, 1-phase; 3-wire, 1-phase; 3-wire, network; 3-wire, delta; 4-wire, delta; 4-wire, wye and 5-wire, 2-phase. The meter forms are based on ANSI C12.10 and are 1S, 2S, 3S, 4S, 9S, 12S, 16S, 36S, 45S, 56S, 10A, 13A, 16A, 36A, 45A and 48A.

Wiring diagrams that are Blondel solutions for combinations of meter forms and system configurations will provide accurate metering under all conditions. Those that are not, may not provide accurate metering under some conditions, such as voltage imbalances. They can be used if based on assumptions, for example balanced voltages. If, however, these assumptions do not hold, there will be systematic error that are not associated with the meter malfunctioning.

Installations that are Blondel solutions should be used whenever possible in order to have the most accurate measurement.

For 4-wire, delta configurations that are not Blondel solutions the window CTs in lines A and B should be twice the ratio of that in line C. The ratio of the CT in line C should be used to determine the multiplier.

For 3-wire CTs, use twice the CT ratio when calculating the multiplier.

For 5-wire, 2-phase configurations, using window CTs, use half of the CT ratio to determine the multiplier.