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Electrical Wiring FAQ (Part 1 of 2)
Section - How do I convert two prong receptacles to three prong?

( Part1 - Part2 - Single Page )
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Top Document: Electrical Wiring FAQ (Part 1 of 2)
Previous Document: Why is one prong wider than the other? Polarization
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	Older homes frequently have two-prong receptacles instead
	of the more modern three.  These receptacles have no safety
	ground, and the cabling usually has no ground wire.  Neither
	the NEC or CEC permits installing new 2 prong receptacles anymore.

	There are several different approaches to solving this:
	    1) If the wiring is done through conduit or BX, and the
	       conduit is continuous back to the panel, you can connect
	       the third prong of a new receptacle to the receptacle
	       box.  NEC mainly - CEC frowns on this practice.
	    2) If there is a metallic cold water pipe going nearby, and
	       it's electrically continuous to the main house ground
	       point, you can run a conductor to it from the third
	       prong.  You MUST NOT assume that the pipe is continuous,
	       unless you can visually check the entire length and/or
	       test it.  Testing grounds is tricky - see "Testing
	       Grounds" section.
	    3) Run a ground conductor back to the main panel.
	    4) Easiest: install a GFCI receptacle.  The ground lug
	       should not be connected to anything, but the GFCI
	       protection itself will serve instead.  The GFCI
	       will also protect downstream (possibly also two prong
	       outlets).  If you do this to protect downstream outlets,
	       the grounds must not be connected together.  Since it
	       wouldn't be connected to a real ground, a wiring fault
	       could energize the cases of 3 prong devices connected
	       to other outlets.  Be sure, though, that there aren't
	       indirect ground plug connections, such as via the sheath
	       on BX cable.

	The CEC permits you to replace a two prong receptacle with a three
	prong if you fill the U ground with a non-conducting goop.
	Like caulking compound.  This is not permitted in the NEC.

	The NEC requires that three prong receptacles without ground
	that are protected by GFCI must be labelled as such.

	See the next section about computers on GFCI-protected groundless
	outlets.

User Contributions:

Dev
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
kevin
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.
dennis
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
dennis
Robert
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 ?
@dennis
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
Report this comment as inappropriate
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: Why is one prong wider than the other? Polarization
Next Document: Surges, spikes, zaps, grounding and your electronics

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Last Update March 27 2014 @ 02:11 PM