Page 398 - IGC BOOK

Earthing

Earthing is the method of transmitting the
instant electricity discharge directly to the
ground through low resistance conductors.
The process of earthing is in case of short
circuit, the conductor removes the overflow of
current and allow the current to flow to the
earth. If the earthing is not done correctly,
then protection won’t be possible.

All the equipment doesn’t require earthing,
equipment may be protected with other
means such as double insulation (discussed
later).

Advantages Disadvantages
• Protect people from electric shock • If earthing disconnected, then no
• Easily identified protection.
• Requires installation, testing and
maintenance.

Isolation

Disconnecting the electrical equipment from the power
sources is called as isolation, this can be achieved by turning
off the equipment first then using a safety locks or pad locks
having a unique key or combination. Padlocks are used where
more than one electrical work is carried out on the same
system.

The maintenance person can place their own padlock on
multiple locking hasp, hence the circuit cannot be re-energised
until all the padlocks are removed. Notices can be placed along
with locks, so that everyone is aware of the work being carried
out.

For example – caution notices. Lockout –Tagout
Advantages Disadvantages
• Eliminates the supply of electricity through • Difficult to find live faults
isolation.
• May isolate sequence of machines
connected.

ENSIGN | Unit IG2 – Element 11 – Electricity 9