20 Amps Circuits


Old 09-11-06, 11:24 AM
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Join Date: Oct 2005
Location: Kenosha, WI
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20 Amps Circuits

I'm installing a new 20 amp circuit in my garage so I can have some additional outlets. Originally, I was just going to go with the 15 amp setup, but then realized 20 would probably be better since I'd be running some semi-heavy duty stuff out there (power tools and the such).

After doing the research, I realize now that 20 amp wire and outlets are visibly different then the 15 amp (with the extra tab on the outlet and the yellow wire), but the 20 amp circuits in my house are not like that (they're missing the tab and the wires are all white).

The house is only five years old. I'm confused as to what's going on. Can you use 15 amp rated wire and outlets on a 20 amp circuit? It must have been up to code at the time it was built, so I don't really know what's going there.

Thanks for your thoughts,
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Old 09-11-06, 11:29 AM
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Join Date: Oct 2005
Location: Kenosha, WI
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Further research gave me this answer:

"The code basically says you can have 15 amp receps on a 20 amp circuit, unless it is a single, dedicated recep, then it must be rated 20A.

But a 20A recep may not be used on a 15 amp circuit."

Old 09-11-06, 11:30 AM
Join Date: Apr 2006
Location: Arlington
Posts: 181
Yes, you can use 15A recepticles on a 20A circuit.

Garage outlets must be GFCI protected. Just buy one & place at the beginning of the run to keep cost down. Just make sure it's 20A like the rest of the recepticles. It will protect all of them.

20A wire. (typically #12/2) Romex should look just like #14/2. Black hot, white neutral & bare ground. (EDIT: Realized you were talking about the insulation on the cable. Yes, 12/2 is typically yellow & 14/2 is typically white)
Old 09-11-06, 11:31 AM
Join Date: Sep 2002
Location: welland ontario
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15 amp circuit requires minimum #14 wire.
20 amp circuit requires minimum #12 wire. You could use #12 on a 15 amp circuit If you wish.
You didn't state you location so I will quote for Canada since that is where I am.
In Canada you must match the receptacle to the breaker size. That means a 20 amp circuit must have 20 amp receptacles. You could use the T slot ones that accept 15 or 20 amp plugs.

The colour of the wire is not relavent. That is a manufacturer thing. It has not been added to the code yet.
Old 09-11-06, 11:45 AM
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The color of the cable outer jacket is not important. In last few years, most manufacturers have made #14 white, #12 yellow and #10 orange; however these colors are not standard and not regulated by code. Cable older than a few years will not be color coded; all sizes were white, black or grey.
Old 09-11-06, 11:57 AM
Join Date: Sep 2003
Location: Central New York State
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People have pretty much summed up the rules, so I won;t do so again.

One comment is wrong, however. In the US, you do not need a 20 amp GFCI receptacle even if the circuit is 20 amps. A 15 amp GFCI receptacle provides 20 amp protection feed through, so don;t buy a 20 amp GFCI recepacle unless you want to.
Old 09-11-06, 09:01 PM
Join Date: Aug 2005
Location: USA
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Some confusion is being encouraged by the use of some wrong terms by a few.

The outer part of a Romex-type NM cable is a JACKET, not insulation.

WIRES are color-coded. The CABLE is not required to be so. The cable consists of multiple wires.
Old 09-13-06, 06:03 PM
Join Date: Apr 2004
Location: Ontario Canada
Posts: 1,767
The only difference between 15A and their equivalent 20A part is the neutral slot having the horizontal slot added.
All the tabs and things are the same for both.

As said, the colored sheathing is a recent innovation. Your home was wired before it became popular, so has only the white colored cable for all sizes.

You need to use #12 for a 20A circuic, but can use 15A recepticles in the USA, you need 20A recepticles in Canada.
Old 09-13-06, 07:11 PM
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what is the deal, with the colored cables anyway?
Be it Nm or mc.
Is it for the inspectors, the electrician,the homeowner or what?
NM, White,yellow ,orange, Why?
Then with the MC, (don't get me started) RED ,blue, blue with orange, orange with green!!!!!! What gives.

Is it so I know what I'm dealing with? Do you realy think someone will go and buy the 20' of propper colored (MC) to complete the ckt? (Nm. doesn't count here, coz color indicates size) Wich leads to another......
Old 09-14-06, 05:52 AM
Join Date: Aug 2005
Location: USA
Posts: 995
The colored cables are for convenience to everybody, especially the installers. Inspectors won't necessarily RELY on it, but it does help them.

Which colors are you referring to in the MC? I see some of the new stuff with bands, like a red band for a 12/3 and a red and blue band for a 12/4, sometimes a black band on everything from 12/2 and up as well.

Also, I've seen red MC to show that it is dedicated to a fire alarm system in commercial installations, and I've seen blue and green for other uses, but those are mostly for convenience of the contractor, in my experience.

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