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How many receptacles can I put on a 15 amp circuit?
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My intuition tells me:
This is dictated by where these receptacles are: kitchen, bath, basement etc.
Someone else step in here and give the law.
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You would be safe putting 8 outlets on a 15 amps using 14-2 wire . Kitchens,Baths, and dinning area use 12-2 wire 20 amps. If you can have your Electrican run # 12 & 20 amps you will be glad you did.
*Use 14 gague wire for switch legs only.Rick Tuk
*You can "safely" put as many as you want, the breaker will protect the wire. From a practical standpoint, I usually limit it to 6 or 8 in most areas and I space them closer than the 12feet that code requires. My own house has 27 circuits but only a 100A service. Murray makes a 30 circuit 100A panel. I don't think that any of the others do. I have a lot of energy efficient devices and have never seen a total load of over 65 amps in my house even with the central air running..I like to use at least 2 circuits for each 2 or 3 rooms with some outlets in each room on each circuit so if one circuit is turned off, there is still a live outlet in the room on the other circuit.I put at least 4 circuits in a kitchen. 1-fridge and stove if it is gas, 1-lights, at least 2 on the counter.
*One practical but weak limitation is the branch-circuit load calculation -- 3 watts per sf. CABO 4204.5. I could swear NEC requires a specific VA allocation per receptacle but can't find it.Anyway, overextending a circuit is against your interests -- I'd stop at about 8 and keep them in a logical layout. I try to make receptacles outlets 20 amp given the unpredicatability of the load -- esp. if someone plugs in a space heater or portable microwave -- and lighting fixture circuits 15 amp because of the ease of working with the 14 gauge wire in existing construction, where the wire must often be fished through awkward paths. I don't like mixing gauges in one circuit because someone someday might overload the smaller wires. A new house, I'd likely do all 20 amp/12 gauge.
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Buzz--
Are you talking about new home construction? I ask because a new house will have central heat and air, and so the possibility of having a space heater or room AC on a general use branch circuit is pretty remote.
For residential general use circuits, the NEC contains NO limits as to how many receptacle outlets (ROs) may be placed on a circuit. The 180 VA/RO requirement is for commercial occupancies, and does not apply to residences. A lot of inspectors don't understand that. However, it's not a bad rule of thumb to use 180 VA per duplex RO and for each lighting outlet. So that means 10 outlets on a 15 amp circuit.
For small appliance (kitchen counter) circuits, the code requires a minimum of two - 20 amp circuits. For a big kitchen, put in more. Also, put in a dedicated one for a microwave (either countertop, or combo range hood microwave).
Bathrooms ROs have to be on a 20 amp circuit (unless there's only one bath, then the bath lighting/fart fan can be on that circuit--this is new in the '99 code).
I will rewire my own house with all 12 gage and go for 10 outlets/general use beanch circuit. I have known electricians who wired their new houses so that each room is on a separate circuit. I think that's overkill. Add up the loads in a typical room--you'll see.
*My electrician has told me he figures 1.5 amps for each outlet. I guess that means he'll wire 10 an a 15A circuit.
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Does anyone have a rule of thumb, or concrete rule, for the # of "RO's" to wire downstream of a GFCI?
I wouldn't rule out the chances of a space heater even in a new home! I have roomed with a fair number of people with bizarre ideas of the ideal temperature. I like things bit cool ("arctic" my wife likes to say) while my 3 y.o. refuses to sleep under any blankets whatsoever. So we have the furnace shut down at night but put an 800-1500W ceramic space heater in his room. (Wouldn't want to be accused of child abuse!) The two of us plus an overweight furry cat do fine at the lower temps.
Buzz has probably received much more detail by now than he ever wanted!
*This is all great advice, as I am currently stumbling through building my own home. Should finish the rough electrical this week. Couldn't agree more about using 12 ga./ 20A for all but switch legs. Just be careful to use large enough boxes for the number of conductors.One question though. Do I need to use recepticles rated for 20A? I understand the code will not allow back-wired 15A outlets with 12ga. wire. Don't really want to splurge for commercial grade 20A recepticles if it's overkill.
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I seem to recall in reading "Wiring Simplified," or one of those other enduring publications, that you must use a receptacle rated for 20 amps if on a 20 amp circuit. I could be wrong and I'm sure you will receive better advise - shouldn't rely on my long-term memory for something I stored in my short-term mind.
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PROVIDED that you have two or more receptacles on the 20-amp circuit, 15 or 20 amp ROs are deemed acceptable. CABO 4501.1-.2.
You don't need the 20-amp ROs with the funny prong configuration, but personally I like the $2 "commercial grade" 15-amp ROs that weigh 8x as much as the 30¢ cheapies. Much sturdier (important with 3-prong plugs) and they accept 12 (or even 10) gauge backwiring with a much improved design. A Leviton rep told me the company "does not recommend" using the spring-loaded backwiring on the cheap ones (!).
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I think the literature that comes with the GFCI's says no more than six outlets down stream. I could swear I read that.
*Rick Tuk and Wedgehead...by 14 gauge "switch leg" do you mean using 14 gauge wire in a 20 amp circuit with otherwise all 12 gauge wire? This is not permitted in my jurisdiction. The reasoning is that somehow a 20 amp load might be installed on that 14 guage wire resulting in melt-down of the wire before the breaker kicks off.
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Noooooo....... All 12 gauge in a 20-amp circuit. I think they meant, use 12 gauge for the long runs, 14 for the fixture branches.
*I agree with Andrew on this one - the 15amp and 20amp spec grade receptacles are inexpensive and far better than the cheaper residential grade duplexes. I don't use them exclusively, but anywhere that I know a significant load will be drawn(kitchens, laundry, workshop, ac, garage, heater, etc). Code allows use of the 15's on a 20a circuit if there is more than one outlet, though there are design limitations. The 15's are limited to a single cord-connected appliance of 12a max, whereas the 20's are allowed a 16a single appliance load (NEC Table 210-21(b2). The 20's may not be used on a 15a circuit.
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Thanks Andrew for giving the code.
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It's a lawyer thing. :)
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CAP, thanks for the E-mail but I think you misread my messages: "I could be wrong ..." and "my intuition tells me ..." are disclaimers. I grouped them with, "... you will recieve better advise (than mine)," and, "...someone else step in w/ the law."
I was speaking off the cuff, as 'Ryan' did in this same post, "I could swear I read that."
Correction on the receptacle-thing noted; it was the Switch of a 20amp circuit that should be rated for 20amp, right? Or is that wrong too?
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I do not believe there was ever a reference in the NEC regarding the specific number of receptacles on a circuit.
There is somewhat of a backwards way to answer. The NEC requires 3 watts (volt-amps) per square foot of living space. This is under the General Lighting section. General Lighting, however, includes lighting plus wall receptacles for general elec usage.
That 3 watts per foot equates to 600 square feet for a 15 amp circuit and 800 square feet for a 20 amp circuit. I've seen it recommended (we use it as well) that in general, not to exceed 12 outlets on a 15 amp and 16 outlet on a 20 amp circuit. I have a paper from some misc building board that uses these numbers. It's 4 years old, however, and references the 1993 NEC. Layout the boxes as required, if you need more then 12 go up to a 20 amp breaker. Obviously, if room usage dictates otherwise, up the breaker, to a 20 amp.
In general I'd advise using 12 ga wire throughout from the panel to outlets. Never, ever use the spring loaded holes on the back of outlets, always use the screw terminals. 18" boxes can be used with 12 ga, but I spec 20" as the minimum. When using screw caps to connect wires, first twist the wire ends together. Don't rely on just a screw cap for youe electrical connection.
Still, if you're not versed in local code, review any proposals with your code official. A simple "can I do this?" question can save a bit of aggravation, time, and money come inspection time down the road.
Careful with electricity. Wiring basic circuits is not terribly difficult. However, if done improperly you can hurt yourself, or worse, a family member.
*"... or worse, a family member." That depends on the family member, Mongo. Even Theodore Kaczynski has family. :) (Too bad he didn't have any wiring.)Interesting if irrelevant tidbit: Ted was done in by the unprecedented publication of his manifesto.From the Post:>Although the FBI amassed thousands of leads over 18 years while futilely tracking the Unabomber, agents did not have a clue to Theodore Kaczynski's identity until his younger brother, at his wife's urging, read a 35,000-word anti-technology manifesto that the serial bomber had prevailed upon The Washington Post and the New York Times to publish. Unabom Task Force agents involved in the manhunt said they may never have found the reclusive, 55-year-old former mathematics professor without the help provided by his brother.
*Do you think Ted's brother will be opening any packages send to him by Ted this holiday season?
*While i was working in the federal court building in Chicago, a crook sent a mail bomb to the judge there who had convicted him. The bomb (a hollowed-out book) was intercepted and destroyed. Not so remarkable in itself, except that the would-be bomber constructed and shipped the bomb while still serving his sentence in prison.A lot of these guys were remarkable for their ingenuity. Dental floss, matches, coffee creamer, eyeglasses ... all sorts of items found their way into weapons.
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How many receptacles can I put on a 15 amp circuit?