Apart from their use in electronics, which we won't comment on,
	and for certain fluorescent lights (they won't turn on without
	a good ground connection), they're intended to guard against
	insulation failures within the device.  Generally, the case of
	the appliance is connected to the ground lead.  If there's an
	insulation failure that shorts the hot lead to the case, the
	ground lead conducts the electricity away safely (and possibly
	trips the circuit breaker in the process).  If the case is not
	grounded and such a short occurs, the case is live -- and if
	you touch it while you're grounded, you'll get zapped.  Of
	course, if the circuit is GFCI-protected, it will be a very
	tiny zap -- which is why you can use GFCIs to replace
	ungrounded outlets (both NEC and CEC).

	There are some appliances that should *never* be grounded.  In
	particular, that applies to toasters and anything else with
	exposed conductors.  Consider:  if you touch the heating
	electrode in a toaster, and you're not grounded, nothing will
	happen.  If you're slightly grounded, you'll get a small shock;
	the resistance will be too high.  But if the case were
	grounded, and you were holding it, you'd be the perfect path to
	ground...


User Contributions:
Dev
Dec 21, 2011 @ 12:00 am
In a fire protection circuit, circuts are shown witha no example 6,8,4etc. what it mean?these circuits are connected between smode detector,junction box etc
kevin
Dec 24, 2011 @ 12:12 pm
My daughter dropped a small necklace behind her dresser. The necklace crossed a plug terminal and shorted the receptacle.

I bought a new receptacle and installed the same. I still have no power  I suspect there could be a bigger problem,this is aluminum wiring.

I've killed the breaker and call an electrician but am curious as to what happened.P.s. there is a dimmer switch on the same circuit.
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