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Electrical Wiring FAQ (Part 1 of 2)
Section - What is a circuit?

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Top Document: Electrical Wiring FAQ (Part 1 of 2)
Previous Document: What does an electrical service look like?
Next Document: "grounding" versus "grounded" versus "neutral".
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	Inside the panel, connections are made to the incoming wires.
	These connections are then used to supply power to selected
	portions of the home.  There are three different combinations:
		1) one hot, one neutral, and ground: 110V circuit.
		2) two hots, no neutral, and ground: 220V circuit.
		3) two hots, neutral, and ground: 220V circuit + neutral,
		   and/or two 110V circuits with a common neutral.

	(1) is used for most circuits supplying receptacles and
	lighting within your house.  (3) is usually used for supplying
	power to major appliances such as stoves, and dryers - they
	often have need for both 220V and 110V, or for bringing several
	circuits from the panel box to a distribution point.  (2) is
	usually for special 220V motor circuits, electric heaters, or
	air conditioners.

	[Important Note: In the US, the NEC used to permit a circuit
	similar to (2) be used for stoves and dryers - namely, three
	conductor wiring, with a ground wire doing dual duty as a neutral.
	As of the 1996 revision to the NEC, this is NO LONGER PERMITTED.]

	(1) is usually wired with three conductor wire: black for hot,
	white for neutral, and bare for grounding.

	(2) and (3) have one hot wire coloured red, the other black, a
	bare wire for grounding, and in (3) a white wire for neutral.

	You will sometimes see (2) wired with just a black, white and ground
	wire.  Since the white is "hot" in this case, both the NEC and CEC
	requires that the white wire be "permanently marked" at the ends
	to indicate that it is a live wire.  Usually done with paint, nail
	polish or sometimes electrical tape.

	Each circuit is attached to the main wires coming into the
	panel through a circuit breaker or fuse.

	There are, in a few locales, circuits that look like (1), (2)
	or (3) except that they have two bare ground wires.  Some places
	require this for hot tubs and the like (one ground is "frame ground",
	the other attaches to the motor).  This may or may not be an
	alternative to GFCI protection.

User Contributions:

Report this comment as inappropriate
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
Report this comment as inappropriate
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.
Report this comment as inappropriate
Feb 24, 2012 @ 11:11 am
Regarding new construction wiring and running 12/2 and 14/3 wire in the same box.

I have multiple switches to lights. Ran 12/2 and 14/3 into switch box and inspector wrote correction needed.

What should I have done instead?

thank you
Report this comment as inappropriate
Nov 26, 2012 @ 9:21 pm
Does a grounding electrode facilitate the operation of a OCPD, to clear a ground fault ?
Report this comment as inappropriate
Mar 18, 2013 @ 10:10 am
Assuming you are installing two switches in a two switch box, you probably should have used 14/2 and 14/3 instead of replacing 14/2 with 12/2. If you are only installing one switch in a one switch box, you should only have one cable in the box.
P k
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Jan 26, 2014 @ 10:10 am
I prefer to use nothing smaller than12 awg /the smallest sized wire on a circuit determines the allowable ampacity
Ex: 15 amp-14awg. 12awg-20amp only rule for thumb other factors such as continuous load,heating and others if you do not know the safe NEC rules then please call a qualified journeyman Electrician better be safe

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Top Document: Electrical Wiring FAQ (Part 1 of 2)
Previous Document: What does an electrical service look like?
Next Document: "grounding" versus "grounded" versus "neutral".

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Last Update March 27 2014 @ 02:11 PM