• Electricity is supplied through “wires”, comparable to pressured
water supply pipes.
• At points along the wires are lighting outlets, switches, and
receptacles. Turning on a light switch or plugging equipment into
a receptacle is comparable to opening a faucet/valve.
Equivalent to water pressure; pump controls water
pressure; generator or battery controls voltage;
standard voltage is 120/240; most common low
voltage is 12V
Electrical current; equivalent to flow of water (gal/sec)
Resistance: Opposition to flow of current; amount
of resistance affected by:
Unit of power; rate at which a device
converts current to another form (heat
(Voltage x Amperage)
Watt-hour: Unit of energy; measures amount of
energy/electricity used in one hour
Watts x hours of use=watthours or KWHR, e.g.,
100 w x 24hrs = 2400 whrs/day
= 2.4 KWHRs
2.4 KWHR/day x 30 days/mo.
= 72.4 KWHR/mo
72.4 KWHR x Rs. 9/KWHR = Rs. 651/mo
Direct current: Current flows in one
Alternating current: Current flows in
single direction but reverses direction at
and Home Wiring
For electrical safety, it is required that every circuit be
grounded. This assures that all metal parts of a circuit that
a person might accidentally touch are maintained at zero
voltage, because they are connected directly to the ground.
The grounding wire is attached to the third slot on a wall
If hot wire touches cover plate of ungrounded switch or outlet, the
plate will be electrically charged. If the body touches the plate, the
body becomes part of the circuit and will receive a shock.