Mains Power means the 230 V AC 50 Hz or 110 V AC 60 Hz in some countries, The lower power line like 5A is used for small lamps and fans. The higher power line 15A is used to drive the High Power Electrical Appliances like Heaters and Motors. This is a single phase supply.
Single phase Supply in layman language means a Live, a Neutral and an optional earth. The earthing is a must in every building along with lightning protection. The Neutral is a close to earth potential, The live can give a shock to a man who is in contact with earth at some part of the human body. So great care has to be taken. This live wire or point can be easily checked by a quality standards approved Neon Tester.
Three phase supply – there are three Live wires, used in factorys and apartments to power bigger loads and Motors. A 3 phase AC motor is very efficient and economical and most machines like Drills and Lathes are powered by AC Motors. 3 phase supply becomes essential for industry.
The voltage is transmitted and supplied to houses at a high level in comparison to low level of batteries. This High Voltage is not safe but Inevitable, as transmitting at lower voltage means greater current carrying requirements of wires and connectors. That leads to more copper or aluminum usage, more wastage of power due to I2R.
Earthing has to be good, use a Earth Leakage Trip Device. If earth wire gets snapped outside and some appliance is leaking, the metal clad appliances may give shock. Even if no appliance is leaking, the current thru y-capacitors of EMI Filters in Electronic Gadgets like computers are enough to make your Neon tester glow.
The Circuits related to Mains Power