I BOUGHT A REFRIGERATOR, IS IT NECESSARY TO EARTHED THE APPLIANCE? WHAT IF I DID NOT EARTHED IT, WHAT WOULD HAPPEN?
All the neutral and ground (or "earth") wires in a building are tied (or
"connected") together at the incoming service main breaker panel - and
that is the only place they should ever be tied together - because it is
"upstream" of all the fuses and/or circuit breakers which are there to
protect the hot (or "live") wires for the various circuits installed in
In the absence of an earth wire (= ground wire in
US/Canadian English), if the appliance suffered some damage that caused
a short circuit between the high voltage "hot" lead and the case of the
appliance, the damage would make the case live and it would cause an
electrical shock to anyone who touched it.
If the case is
earthed by using a ground wire (= earth wire in British English), if
that same damage occurred the hot lead would immediately be shorted to
ground and in theory cause the fuse to blow or circuit breaker to open,
thus eliminating the danger of a live case.The ground or "earth" wire is a circuit's safety protective wire that normally carries no current.
It is there to force a fuse to blow or a circuit breaker or GFCI to
trip if a fault condition occurs in any appliances, their flexible cords
or plugs that are connected into the circuit.
By carrying away
the excess current in a fault condition - which should cause the
protecting fuse to blow or circuit breaker to trip - the "ground" or
"earth" wire protects the building and its occupants because the power
should be cut off before anyone gets electrocuted or any overloaded
circuit wiring or appliances catch on fire.
The neutral is the
normal "return" wire: in systems where the load is supplied from only
one hot (or "live") wire, the neutral completes the circuit and carries
current back from the load to the power station.
neutral and ground (or "earth") wires in a building are tied or linked
together at the incoming service main breaker panel. This is the only place they should ever be tied together
because it is "upstream" of all the fuses and/or circuit breakers
protecting the hot (or "live") wires for the various circuits installed
in the building.
Warning: we must never assume that a
neutral is safe to touch: it has to be checked with a voltmeter or a
voltage indicator to be sure it is not "live". This is because a neutral
wire is designed to carry current under normal circumstances.
So, if a neutral wire going back to the incoming main breaker panel has
not been properly connected - or suffers a deliberate disconnection or
some accidental damage which causes it to break - then it and any
neutral wires connected to it further downstream will go live up to the break because of being connected to the downstream loads which still have hot feeds coming into them!
That is why we should never use a neutral as a substitute for a proper, separate, ground or "earth" wire.
Aug 01, 2011 |