Single Phase 2 wires system

• Single-phase alternating current is graphically represented as a sine wave 
• At 50Hz frequency , the voltafe in each wire is positive and negative 50 times each second and 100 times  no voltage at all in the wire . 
• The voltage is never constant , but is always changing . 
• In a 240 volts service , the maximum voltage is about 340 volts , but the average amount is 240 volts and hence that is the effective voltage . 
• Because the fluctuation occurs fast enough , there is no apprarent nterruption in the output of electrical equipment .