Getting ready to wire new addition. There will be about 20 15amp outlets around the house, maybe a few more depending on how the inspector interprets things. This excludes kitchen and bathroom outlets. What’s a practical number of outlets to put on one breaker? I’m putting in a 100amp subpanel so there will be plenty of slots to use, but habit tells me not to waste them.
Lighting is a lot easier these days with LEDS, I can put all the overhead lights on one breaker no problem with some current to spare.
Based on one link I saw (that gave a calculation )the number would be like 8 on a 15 amp breaker, but that was not referencing any official location.
It said only count 80% of the breaker rating (12 amp), and then allow 1.5 amp per outlet, so that came to 8. Other places just gave a general number with no particular reasoning.
I may do that for just that reason. I’m thinking of adding some closet lights too so I could add those to one of the lines. There will be some future overhead lighting I can put boxes in for now.
That sounds about right. I could run three different lines for the different areas of the house with 6 to 8 outlets on each one. I’ve been looking for a formula like that. With all the outlets needed for code I can’t see any run getting overloaded easily.
Yeah, the rough general rule of thumb is no more than 8 outlets per breaker.
I would look at what might get plugged into those outlets, though. If someone might put a window air conditioner in each room then you’d want each room on its own separate breaker, for example. I don’t know what the layout is in your addition, but the more you split it up, the less likely you are to run into problems when someone sticks a heater or a hair dryer into an outlet that’s already on a heavily loaded circuit.
I also agree with the recommendation to split the lighting onto two circuits so that you aren’t without light if there’s a problem.
I am considering putting a 20amp outlet in the bedroom for a room air conditioner. We’ll put in a split system AC eventually but we may want that short term. The overhead lights shouldn’t be a big issue but it just makes sense to run more than one line now. I have an access into the ceiling area so I can change things later if need be, but I’m too old to wiggle through trusses, once the drywall is up on the ceiling I never want to go up there again.
I’m also considering putting one GFCI on each outlet run. Probably unnecessary but just another thing to do early on while it’s easy. The bathroom and kitchen will need them anyway on 20amp circuits.
Note that this is a rule of thumb. There is no limit based on current electrical code in the US - as long as the breaker is sized for the minimum size wire on the circuit (20A for 12 AWG, 15A for 14AWG). There are special rules when there is only one outlet on a circuit (mainly you need to use a 20A outlet if it is the only outlet on a 20A circuit), but that usually only comes into play in special circumstances.
I prefer each room has its outlets on its own breaker, and any ceiling lights on a different circuit.
ETA:
A heater is a good consideration too, maybe another 20amp outlet in the great room. We’ll be short on heat for a while, I’m cutting back the zone in the old house so the boiler can handle the new load. I’ll need a new or second heating system eventually, but another short term consideration will be some supplemental electric heat.
Aside from the kitchen and bathroom there are really just two rooms, a great room and a master bedroom. The master bedroom has no overhead lights, I’ll put those outlets on one line, the long from wall of the structure that is one side of the great room and a hallway will be on another line, and the common wall and dining area on another. There will be four overhead tracks in the great room and kitchen and I’ll split those into two lines.
Another thing I like to see is when a room has a switched outlet (like your bedroom with no ceiling lights is required to have) is to run the 12/3 or 14/3 wire (which includes the switched hot wire) to all the outlets in the room, not just the one you plan on having switched. That way if you change your mind later any outlet in the room can be easily converted into a switched outlet.
Also I would seriously consider pre-wiring for a ceiling fan - way easier to do now than later…
Yeah, my wife’s on me about the ceiling fan, so I’ll have to put one in to cut down on the noise. I like the idea of running 3wire to all the bedroom outlets, and I do need the switch on one. The peak of the cathedral ceilings is in the bedroom so i may wire a box up there on a switch for a future fan or light fixture. Of course all these future considerations are adding up to more work and money, eventually I’ll have to pick the top priorities. I’m already drilling extra holes into the basement through the base plates of the exterior walls because that will be very difficult to do in the future, and once I start that can of fireblock foam I’ll have to use it all up anyway.
I am not an electrician, but I thought 15 amp circuits were obsolete decades ago. When I converted two of my houses from fuses to breakers in the late 70’s, the electrician said the standard minimum circuit was 20 amps. He put in 15 amp breakers only for some ceiling lights that were already wired with smaller gauge wire, and had no outlets.
My friend is a master electrician, he recommended using 15 amp outlets except where code dictates 20. His reasoning is that most things plugged into them are using 18 gauge wire that could get seriously hot before tripping a 20 amp breaker. I don’t really see it as a problem but he knows the local inspector and what he’s actually telling me is that it will be easier to pass if I just use the 15 amp outlets. The old part of the house is a log cabin that is difficult to wire so I have 20 amp outlets everywhere. As mentioned I’ll have 20 amp outlets where needed for code such as the kitchen and bath, and I’ll do the whole basement and exterior outlets as well.
I would go with 12 gage wire and 20 amp breakers. Most new homes in our are have 20 breakers for outlets and 15 amp on lighting circuits. I started wiring my house that way.
But that meant that I had to buy 14 and 12 gage wire. I changed to only using 12 gage wire. If I run any wire from the panel or add to a line that I know for a fact is only 12 gage then I will connect to a 20 amp breaker.
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I’m also considering putting one GFCI on each outlet run. Probably unnecessary but just another thing to do early on while it’s easy. The bathroom and kitchen will need them anyway on 20amp circuits.
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Spend a couple more bucks up front and buy combo AFCI/GFCI breakers. AFCI (arc-fault) is required for seemingly any general receptacle in living spaces now, and adding GFCI functionality doesn’t add much to the price of the breaker.
For residential applications the last time I checked the national electric code does not place a limit on outlets for residential applications. Some local codes expand the 8/10 code for non-residential applications to residential applications.
I like to do things the thorough way and put every room’s receptacles on it’s own 20 amp circuit (generally four or five) and a few separate 15s for the lights (but I don’t really use LEDs). I got tired of popping breakers because I tried to use a spaceheater in one room and a computer in the next when there were only a couple of 15s for the house shared between rooms and the lights
Likewise am in the middle of re-wiring my house, and I have installed no #14/15A circuits. IANAE*, but from distilling all of the advice I received and found decided that there was really no reason to do it otherwise. #14 is easier to work with, though.
I give each bedroom their own 20 amp outlet circuit. I don’t like 15 amp outlet circuits in general, it’s too easy to trip them using a vacuum, space heater, ac unit or power tools if there is much else on the circuit. Lots of people use a space heater under their computer desks, between the heater and the computer they’ll trip a 15 amp. They can trip a 20 amp too but they have to try a lot harder.
Lighting on each floor gets broken up between 2 15 amp circuits.
Around here we /used to/ put the lights on a seperate circuit, back when the wiring rules were different for lights and power.
But right now, our wiring rules are the same for lights and power, and the recomendation is to put them on the same circuits. So that when you blow a socket, you know because a light is also out.
But then you’ve got no lights to see and fix the problem. Doesn’t make sense to me, but what do I know.
I’m in the middle of wiring my pole barn. All receptacles are 20A and 4 on a breaker. Lights are all on one 15A breaker and are LED. I think the total load is around 8A or less. I’ve also got a 50A 240V circuit for a welder.