1. http://www.analog.com/energymeter Wiring standards Single phase, 2-wire 120V or 220V Single phase, 3-wire 220V between phases ; 110V between phase-neutral Three phases, 3-wire No neutral ; 220V between phases Three phases, 4-wire 220V between phase-neutral ; 380V phase-phase

2. http://www.analog.com/energymeter Fault Tolerant Energy Metering AD7751 - monitor phase and neutral currents

3. http://www.analog.com/energymeter Anti-Tamper 2 wire, 1  Meter Example AD7751: 1  Real Pwr, anti-pilfer, Motor Drive AD7751 Gain Calibration +5V ac to dc Power Supply Reverse Polarity LED ADC2 ADC1A 10011... 11100... Neutral Phase Residential Outllets Line Voltage Stepdown I Phase <I Neut Digital Comparator * X I Neut I Phase PGA I Phase >I Neut 11100... 10110... 11110... V ADC1B Calibration LED Fault Detection LED Digital- to- Frequency Load Side * Note: Digital Comparator Selects > of I Phase or I Neutral PGA Input Side Counter 0098237 kW-H

4. http://www.analog.com/energymeter Basic 2 wire, 1  Meter Example AD7750/5: 1  Real Pwr, Motor Drive output Residential Outllet AD7750/5 X Digital- to- Frequency ADC1 ADC2 Line Voltage Stepdown Gain Calibration +5V ac to dc Power Supply Neutral Phase Reverse Polarity LED Input Side Load Side 101011... 111001... 1101.. Counter 0098237 kW-H PGA Calibration LED

5. http://www.analog.com/energymeter ADE7756/3:  Processor based Meter Example (remote reading or multi-tariff billing) Residential Outllet ADE7756/3 X Registers & Serial Interface ADC1 ADC2 +5V ac to dc Power Supply Neutral Phase Input Side Load Side 1011... 1101... 1101.. PGA Calibration LED DTF Calibration MCU & LCD Driver LCD Display EEPROMComm