I’m fixing up the third floor bedroom, repairing plaster mostly, when it occurs to me that another electrical outlet would be needed on the west wall, if not two. I have limited electrical skills- I can wire up a fixture or replace an outlet. My question is, should I splice into the wire going into the existing outlet, or connect to the other side of the outlet?
Some details:
The existing outlet is on the west wall, and is on the same circuit as the lights and one other outlet. The hot for the light is off this outlet.
The breaker (which is off, I checked) is rated for 15 amps.
110 volts.
As long as you’re using the screw terminals and not the push-in “back-stab” holes, you can connect the new wire to the other set of screws on the outlet.
Couple of notes:
If this is a multi-wire (aka “shared neutral”) circuit that also has a red wire in the box or cable, there’s a code requirement to pigtail the white neutral wires, rather than connecting them at the outlet’s screw terminals to prevent something called a “loose neutral” which could suddenly turn a 120-volt circuit into a 240-volt circuit.
You really don’t want to use those back-stab holes ever. They’re very good at going bad, and on an outlet where you’re expecting a high-draw use like a hair dryer or curling iron, you’re just asking for problems.
Is the existing outlet a GFCI? If not, is the bathroom protected by a GFCI located elsewhere in the house? If not, you need to replace the original outlet with one, then connect the new outlet to the GFCI’s “load” terminals.
eta: About pigtails… The current (ha!) “best practice” is to pigtail everything so only one wire of each color is connected to an outlet. Sometimes, best practices have to take a back seat to practicality if the box is jammed full of wires and there’s not room for more bits of wire and wirenuts. This is especially a problem with GFCIs as they take up a lot of space in a box, and it’s impossible to connect more than one wire to a terminal on them. You just have to carefully finagle everything in, sometimes.
For a circuit protected by a 15 amp breaker, you can use 14/2 NM cable (#14 AWG black and white plus a bare ground-aka Romex). Your connections must be made in a device or splice box, and if the box is too small, it should be replaced with a deeper one. If you’d like to meet current spacing, locate receptacles no further than 6’ apart. If the room has radiant electric heat, don’t locate a receptacle above the heater unit.
I believe a 15 amp, 120v circuit is not considered code for more than a few overhead lights; 20 amps is minimum for other wiring. And I don’t believe code lets you share overhead lights with wall sockets anymore. It’s things like this that suggest that a licensed electrician on the job would be a good idea, given what appears to be your level of expertise. Safety is not a good place to compromise.
Speaking from a realtor’s point of view, when I get houses inspected and find amateur circuit modifications like this, it triggers a more careful look, and can cause the seller to pay for repairs that wouldn’t have been needed if the job had been done right. So think ahead if you own the property.
An electrician might charge you from $50-100 to properly wire up another circuit. Maybe you can get some other work done at the same time and save money overall.
None of that is true. A 15-amp circuit can supply several light fixtures - up to 1440 watts total. You only need 20-amp circuits for the outlets in the kitchen and bathrooms. Outlets and light fixtures can exist on the same circuit.
Edit: Assuming NEC is in use in your jurisdiction. It is National after all.
This probably overstates the restriction -- basically, it's a good common sense practice to not have all the lights in a room share a circuit with the outlets, because if you blow a circuit breaker, you don't want to be fumbling around in the dark. The code may (I seem to recall) mandate a separation in bathrooms and kitchens where the consequences of being left suddenly in the dark might be serious.
Are we talking code, practice or theoretical current-carrying capacity? I had some major house rewiring done in California decades ago and although some existing 15amp circuits were not overloaded, the contractor claimed that they would not be kosher for adding outlets and the wire size was too small to upgrade to a 20 amp breaker, so we let them be. It could have been good practice or just advice, maybe not a code requirement.
The very fact we are having this discussion lends credence to my suggestion that the OP use a professional electrician and not just rely on us “experts” on SDMB.
When major rewiring is done, a wise contractor will redo the load calculation for the dwelling, and the AHJ will wish to view that. I don’t recall any SDMB “expert” advising otherwise.
This is probably going to be the last thing in this house that would give a realtor pause. It’s over 100 years old, and was split into three, and then two, apartments. The previous owner (Jim, a friend of my wife’s) turned it from the Fight Club house into something a bit nicer, while maintaining the option for two-units. Most, if not all, of the wiring has been replaced with Romex, the leftovers of which I found in the basement for this project. The wife bought it before we were married, and so I’ve been conscripted to finish up the redo.
Basically, I just wanted to run the idea of not splicing for the new outlet. So I’ll just run the Romex off the other screw terminals.
I was talking code. In practice, the NEC sets minimum requirements. Electricians often go beyond code. For example, if you wire a room to code there need only be one outlet for each 12 feet of wall space (this is the minimum practical application of the rule that every point along a wall must be no further than 6 feet from an outlet). If a room is 12 feet square, that means only one outlet per wall. Most people want more than that and many electricians and contractors exceed the code requirement in this case.
The NEC says that the expected load on a circuit must not be more than 80% of the circuit’s capacity. A 15-amp circuit has a capacity of 1,800 watts. 80% of 1,800 is 1,440. There’s no specific rule that says “You can only have N outlets per circuit.” Rather, the electrician is supposed to calculate the expected load on the circuit and limit the number of outlets appropriately. In practice this means that, even though you could put 10 or more outlets on a circuit, you should keep the number low. People will use space heaters, computers, and all sorts of other high-draw electronics.
Your contractor’s rationale for not extending the existing circuits was simple - to know whether the circuits had spare capacity he would have had to determine what outlets were on each circuit. It’s a lot easier to just add new circuits and not worry about the existing ones. He should have (and may have) also done a new load calculation for the entire house. This is important, since you are supposed to make sure that the existing electrical service can supply all the power the house needs and you’re supposed to balance the loads at the panel.
The contractor was correct that you can’t put a 20-amp breaker on a circuit that is wired with 14-gauge wire. This is a code requirement.
Authority Having Jurisdiction. Nice try.
Has your jurisdiction even adopted the '08 code yet? Most haven’t.
…getting back to the OP, it would be best in this situation to take some photos of the room in question along with a list of how many outlets and lights are already on that 15 amp circuit. You can post the photos for us all to see or e-mail them to me and I can attempt to walk you through this, if I sense that it’s fairly easy. Working on outside walls with insulation packed in them or closed up walls on the third floor of a dwelling can be really challenging. You may need to do more plaster/drywall work than it’s worth in the end.
In a round-a-bout way there is. I believe the code says you should consider each opening in a dwelling use 100 watts (IIRC), so you can only put 14 devices on a 15 amp circuit. In practice I never come close to this (unless the costumer has a shit-load of can lights on one switch) so I haven’t had to look this one up in a while but I can find the relevant paragraph when I get back to the truck.
The circuit, with a 15amp breaker, has one outlet on the east wall, one on the west wall (which I will be drawing off) and right next to that for the room next to it. There is also the one socket closet light and two socket main light. The outlet I’m pulling off is the end of the line. There is a baseboard heater on the other side of the wall (on a seperate circuit) of this outlet, and the new outlet will be about 8 feet away. I’m thinking I can put another outlet off of the east wall outlet, so there will be four outlets in the room, plus one in the closet. The Romex is 12-2.
Great, the 12/2 is good for 20 amps but you don’t know for sure if it’s 12/2 all the way to the breaker so it’s best to treat this as a 15 amp circuit anyway.
You should be OK to do what you describe here as long as you are careful with the box fill (12/2 cuts down your box fill considerably) and how you guide the romex through and around the wood studs. Be sure to keep it far enough back that you won’t hit it with drywall screws later on. Also, be sure to staple/fasten the romex properly and make good clean/tight splices for those pig tails.
This sounds like a fairly easy project, the hardest part will be getting the romex from box to box (unless you have the walls completely open already).
It is oversized for a 15amp breakers. It will work fine (just be harder to install), but it is generally recommended against because of the risk that some future homeowner will see 12-2 cable and assume that it is a 20amp circuit. Consider buying some 14-2 NM to use for this, and save the 12-2 for another project.
P.S. One hint: when you are installing outlets like this, it’s almost no extra work to install a double box with 2 outlets (4 places to plug in stuff) instead of a single one. And given the continuing accumulation of electrical ‘stuff’, the extra outlets can sure come in handy.
I’ve already run the romex thru the studs behind the base board, so I don’t have to worry about that. My real concern was whether I have to split the new leg off the wire to existing outlet, or can I just use the second set of screws to continue the circuit to the new outlet.
I’m pretty sure that the rest of the romex is 14/2, so I consider it 15 amp.
