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Electrical Wiring FAQ (Part 2 of 2)
Section - How should I wire my shop?

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Top Document: Electrical Wiring FAQ (Part 2 of 2)
Previous Document: What is this nonsense about 3HP on 110V 15A circuits?
Next Document: Doorbell/telephone/cable other service wiring hints.
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	As with any other kind of wiring, you need enough power for all
	devices that will be on simultaneously.  The code specifies
	that you should stay under 80% of the nominal capacity of the
	circuit.  For typical home shop use, this means one circuit for
	the major power tools, and possibly one for a dust collector or
	shop vac.  Use at least 12 gauge wire -- many power tools have
	big motors, with a big start-up surge.  If you can, use 20 amp
	breakers (NEC), though CEC requires standard 20A receptacles
	which means you'd have to "replug" all your equipment.  Lights
	should either be on a circuit of their own -- and not shared
	with circuits in the rest of the house -- or be on at least two
	separate circuits.  The idea is that you want to avoid a
	situation where a blade is still spinning at several thousand
	RPM, while you're groping in the dark for the OFF switch.

	Do install lots of outlets.  It's easier to install them in the
	beginning, when you don't have to cut into an existing cable.
	It's useful if at least two circuits are accessible at each
	point, so you can run a shop vac or a compressor at the same
	time as the tool you really want.  But use metal boxes and
	plates, and maybe even metal-sheathed cable; you may have
	objects flying around at high speeds if something goes a bit

	Note that some jurisdictions have a "no horizontal wiring"
	rule in workshops or other unfinished areas that are used
	for working.  What this means is that all wiring must be
	run along structural members.  Ie: stapled to studs.

	Other possible shop circuits include heater circuits, 220V
	circuits for some large tools, and air compressor circuits.
	Don't overload circuits, and don't use extension cords if you
	can help it, unless they're rated for high currents.  (A coiled
	extension cord is not as safe as a straight length of wire of
	the same gauge.  Also, the insulation won't withstand as much
	heat, and heat dissipation is the critical issue.)

	If your shop is located at some remove from your main panel,
	you should probably install a subpanel, and derive your shop
	wiring from it.  If you have young children, you may want to
	equip this panel with a cut-off switch, and possibly a lock.
	If you want to install individual switches to ``safe''
	particular circuits, make sure you get ones rated high enough.
	For example, ordinary light switches are not safely able to
	handle the start-up surge generated by a table saw.  Buy
	``horsepower-rated'' switches instead.

	Finally, note that most home shops are in garages or unfinished
	basements; hence the NEC requirements for GFCIs apply.  And
	even if you ``know'' that you'd never use one of your shop
	outlets to run a lawn mower, the next owner of your house might
	have a different idea.

	Note: Fine Woodworking magazine often carries articles on shop
	wiring.  April 1992 is one place to start.

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
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 2 of 2)
Previous Document: What is this nonsense about 3HP on 110V 15A circuits?
Next Document: Doorbell/telephone/cable other service wiring hints.

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Last Update March 27 2014 @ 02:11 PM