View Full Version : 15 AMP receptacles on a 20 AMP circuit with 12 gauge wiring

July 20th, 2004, 12:34 PM
I've recently been going through my house and replacing the receptacles and switches, since most of the old ones have paint on them and some are chipped. Anyway, I replaced all the ones on the 15 AMP circuits with no problem. However, I have 3 - 20 AMP circuits that are all attached to 15 AMP receptacles and switches. I took a look at a couple of the receptacles on one of the circuits and they are hooked up with 12 gauge wiring. I used a wire stripper to measure. The townhouse is about 30 years old and I believe some of the receptacles are the original, but there are definitely some newer ones in the kitchen. I have only been here about a year. Everything seems to work fine, although I don't use the 20A circuits a lot.

I wonder: If it is wrong or is it acceptable? Why it might have been setup like this? If I replace the receptacles, should I use 15A or 20A?

July 20th, 2004, 03:24 PM
your allowed to install either 15 or 20amp receptacles on a "20AMP" circuit. However you must not use 20amp rated outlets on a 15 amp circuit.
A fifteen amp receptacle is rated at 15amp per plug in. Most 20amp rceptacle are t slot and very vew circuits

July 20th, 2004, 03:29 PM
would you recommend replacing with 15A or 20A receptacles? The 3 - 20A circuits I have are: dedicated for clothes washer, kitchen countertop and living room area.

July 20th, 2004, 11:46 PM
I've never had a device that used a 20A plug. To me, that is the only reason to use a 20A "T slot" receptacle. You can spend the extra money if you want to for 20A T slot receptacles, but a 15A receptacle is rated for 20A at its screws because both of the 15A outlets in that one duplex receptacle may be used together and max out the circuit (say 10A + 10A). Likewise, 20A may be drawn downstream, so again the screws must pass 20A to get a UL listing.

July 21st, 2004, 05:28 AM
agree with t slot use not necessary. Although even if UL approved have seen some, both switches and recepticles personally would'nt use. As far as down stream loads as mentioned, this would pertain to using receptacle as a junction point. Always liked making pigtails never used the device as a splice point. A personal choice here. GFI would be only place.

July 21st, 2004, 01:59 PM
followup from original poster......

So the only difference between using a 15A or 20A receptacle would be the t slot on the 20A one?

Can't you still use a "regular" plug in the t slot?

What if I had a device that was greater than 15A, woud I be able to use it on the 15A receptacle?

July 21st, 2004, 05:28 PM
yes you can use regular plug in on a T Slot receptacle.
Regular outlet will handle 20 amp load, if more than a 20 amp load your circuit will trip off anyways. Must remember wire also only rated at so much, thus now the circuit breaker protects you and your wiring. If your awhare of a larger load as asking then you would need to cinsider a larger circuit. Many if's here

July 21st, 2004, 09:34 PM
The 20 amp receptacle will work fine, but they are more expensive. I re-did my entire kitchen with black 20 amp receptacles (Had to order them). Although I could have used a standard 15 amp recep (two screw), I perfered to go the other route.

Just my two cents!

July 21st, 2004, 09:42 PM
I'll just chip in here too...

While most folk will never need the T slot ability of the 20 amp receptacles, they have other merits as well. If the receptacle sees frequent interchange of appliances (like at kitchen counters), there's no doubt that the 20 amp receptacles are built much more sturdily. The plastic portions are much more "bulky" and the 20 amp receptacles always have double wiper contacts inside the slots. This allows the receptacle to retain the plug tighter, have better contact, and have a longer life.

On the other hand, if you have a 20 amp dedicated circuit run to the clothes washer, there'd be little value in using a 20 amp receptacle. The clothes washer doesn't need the 20 amp receptacle's t slot, and is seldom or never interchanged. Receptacle "wear and tear" isn't an issue in this instance.

July 22nd, 2004, 04:01 AM
I guess to answer posters entire question then 20 amp rated switches would be the norm If using 20amp rated general lighting circuits, as I would see them getting the most use.

July 22nd, 2004, 09:33 PM
Switchtes per Code requires to be sized in rating equal to the load they control not concerning the amp rating of the circuit. 15 amp on 20 amp circuit is fine if the switched load does not exceed 15 amps. Remember many switches only carry 2 to 6 - 60 watt bulbs yet some switches carry an entire case of 60 watt bulbs on one fixture.

REceptacles may interchange 15 or 20 amp for general use receptacles per NEC rules. 15 amp on 20 amp rated circuit is fine per Code rules.

Switch rules differ from receptacle rules.

Hope this helps


July 22nd, 2004, 09:37 PM
Along that line (with regard to switches), I've always wondered why the code would allow a switch to be sized with respect to the connected load, but one must size the conductor for that load (on the load side of the switch) in accordance with the overcurrent protection. Seems like a contradiction.

July 22nd, 2004, 09:59 PM
You are very observant. And yes it is disconcerting that you are right in what you are wondering. Me too. That is the Code though.


July 22nd, 2004, 10:41 PM
another followup from original poster.....

I am going to replace all the receptacles and switches with 15A ones. There is only one switch on one of the circuits and it controls a receptacle that I will have a light (with a 60 watt bulb) plugged into it. Am I OK with this?

July 23rd, 2004, 01:10 AM
Yes your OK.Reread last couple posts!

July 23rd, 2004, 01:47 AM
MD & WG, I quess in my mind, I probably felt the same way.See how this is now worded.TY
Again this maybe why the code had always driven me nuts.(in understanding?) And generally there was no one who could answer those type of questions.
I quess I should really have thought this over before asking the question, as rare for a 15a load to be applied to a snap sw in a residential setting. :o Maybe a possibility today, with the huge homes being built.Years ago some of these were viewed as mansions. Then again the spec's on the blueprint more than likely required all 20amp rated switches, top of the line, even though not required.(same with receptacles)
Possibly this ruling will be rewritten, as more and more use of 20a(#12) circuits are now being installed for general lighting.(opposed to 15amp) Starting to think poss why I may have questioned? Still doe'nt mean a 20amp load will be applied but It's a done deal from the get go.
Do not know if my thinking would be right here, but possibly like breakers for lighting, now a switch rated breaker must be used when switching lighting, possibly today they are all sw rated. I can remember breakers going bad when used for turning off lighting banks in commercial setting. Then somewhere in there the sw rated breakers came to light. Just some thoughts.

Again thanks for clearing up my sw statement.

July 23rd, 2004, 05:59 PM
I have some trouble finding "framed" 20 amp switches. Maybe they don't even exist? I hesitate to use 20 amp rated switches in the same gang box with framed 15 amp rated switches, because the unframed 20 amp ones look different (even after the cover plate is installed). This is normally objectionable to the customer.

July 23rd, 2004, 07:30 PM
yet another reason to go all 20's, safety looks all covered done deal. To easy, but then again those service calls are nice for putting food on the table. What yah think. Can't put yourself out of work.

July 23rd, 2004, 08:26 PM
Possibly this ruling will be rewritten, as more and more use of 20a(#12) circuits are now being installed for general lighting

I hope not! It's a pain dealing with #12! Outside of that, it's not needed. If it gets to a point that the lights require more, then run the lights on a separate circuit from the receptacles.

July 23rd, 2004, 08:36 PM
Well, OHM.. I'm doing a house right now that has so many lights that have to be switched with one switch that I'm using several 20 amp lighting circuits. The outside of the place has so many recessed lights in the soffits that come on with one switch that it's a 20 amp circuit. The dining room has a mess of lights and one HUGE chandelier that it's a 20 amp circuit. You're right though, I try to only run 15 amp lighting circuits when at all possible, and keep them seperate from receptacles.

July 23rd, 2004, 09:23 PM
You might think along hte line of a lighting relay that can have many poles controlling as much as 4 - 20 amp circuit powered light fixture [huge bulb load fixtures] by controlling of one 15 amp light switch looking same as all other light load lighting switches.

Second option is using smart switches with RF signal assigned relays. [relays again, huh]

Just some thoughts


July 23rd, 2004, 09:26 PM
I know that we do warehouse, supermarket and department store lighting in this manner, but I never considered doing residential this way. Lighting contactor and NEMA 1 housing is a couple hundred clams.