Hello. Welcome to Just Answer. Thank you for requesting me to answer your question.
If you have an outlet in the attic, there is no issue at all with tapping into it to feed a motion light.
The only thing to consider is the amperage rating of the breaker feeding the attic outlet. The rating of the breaker determines the size of wire you need to use.
If it's a 20 amp breaker, you need to use #12 Romex type copper wire. If it's a 15 amp breaker, you can use #14 wire.
Make sure you mount a junction box at the location of the fixture, to enclose the splices from building wire to fixture wire. Just mount the fixture over the box, to enclose the splices.
Currently my home's air unit is plugged into the outlet. Would that give you an indication on the amperage?
Not really. If you don't want to trace the circuit down to find the breaker rating, just use #12 wire. That way, you'll be safe, regardless of breaker rating.
The cost of the #12 wire over #14 wire isn't that much higher anyway, especially for shorter rolls.
OK great. I'll be mounting the light to a ceiling box. is that a proper way to enclose the splices?
Yes, it'll be fine. If the box is below the soffit (exposed), use a weatherproof model. If it's above the soffit, with the soffit cut out around it, you can use a nail on box.
Perfect. what's the proper way to "tap into the outlet"?
What type of box is the outlet mounted in? Is it metal, plastic, fiber? Does it have round knockouts you can take out to install a Romex connector?
Going off memory i'm not sure exaclty. I think it's a plastic box
The home was built in 2010 if that is any indication
OK, it probably won't have round knockouts, as it's likely a residential grade box. With those, there are different types, but most have a plastic tab that sits against the wire, to help hold it in place. Just be sure the outer jacket goes into the inside of the box by about half an inch. If the outlet has screws on the sides that don't have wires already curled around them, you can curl the new wires around that set of screws. Black wire to gold screw, white wire to silver screw. Splice the bare wire to the existing bare wire, by twisting the two tightly together. Ideally, you can remove the bare wire from the ground screw, splice the two ends together on the bares, and add a 6" piece into the splice, with the other end of the short piece going back to the ground screw on the outlet.
This is known as a pigtail. If all screws already have wires on them, you will need to pigtail the black and white wires as well.
Don't try to poke any wire into the push-in holes on the back. #12 doesn't fit those holes well (too large), and we don't like the holes anyway.
I think I understand. You pigtail because the screw can only hold one wire, so you're actually twisting 3 wires together with the short piece going to the screw?
Yes, exactly. You understood that very well. Most people need clarification, probably because I don't always explain it well.
I'm following you so far. To verify the breaker rating, would one find that info in the breaker box itself?
You would need to find the breaker for the circuit that feeds the outlet you are tapping into. Then, look on the face of the breaker itself, and you'll most likely see a "15" or a "20" stamped or printed. Sometimes, depending on brand, it's on the actual switch handle of the breaker.
Ok, that sounds easy
Back to the outlet box. Would it be easier to switch the box out with one that is easier to connect another wire to?
If you have an assistant, you can take a test meter, a radio, or a lamp into the attic with you. Have the assistant turn breakers off, one at a time, until the lamp/radio/meter goes off. You may find installing a larger box makes it easier to contain additional wires that you'll be adding.
You can get a deep 4" metal box. It will have round knockouts on it, for wire entry. There are single gang outlet covers available for these types of boxes, and you need a Romex connector for each wire.
is the romex connector there to fill the knockout you put the wire in?
There are plastic snap-in connectors for the wires now, which I really like. They are much faster and handier than the old metal type, with 2 screws on them. Yes, the connector is basically a clamp and a grommet, to hold and protect the wire.
I can post photos of the type I like, if you think that's what you want to use.
Do you live near a Lowe's store?
Yes, very near one and pics would surely help.
No problem at all. Do you mind standing by?
nope. standing by
a pic of the box you described would be nice too.
Here's the box...http://www.lowes.com/pd_70965-427-8232_0__?productId=3129407&Ntt=4%22+junction+box&pl=1¤tURL=%3FNtt%3D4%2522%2Bjunction%2Bbox&facetInfo=
Nice. Just drill it right to the stud with the rear holes?
Yes, that's fine. There are also models available with a nailing bracket along one side, if you prefer.
Looking for the snap-in connectors now. Not sure what Lowe's calls them.
That's not a link from Lowe's, and their model is slightly different. But it works exactly the same way.
Ok, I'm sure they'll be in the electrical section and easy to find.
If you tell the clerk from the electrical department you are looking for a black plastic snap in connector for Romex type wire, they should be able to help you find it.
They come in multiple sizes, you want 1/2".
I need to post a pic of the cover you need for the box.
any precautions to consider when running the wire to the fixture?
Don't drive your staples too tightly. If you get the staples with two nails in a piece of white plastic, you'll be less likely to damage the wire, even if you would happen to get the nails too tight.
ok. just nail it to the exposed studs and I'll be fine?
That's the cover you need. Yes, nail to any exposed framing in the attic, no real Code concerns there.
I can try to find the staples on Lowes' site, if you like.
Perfect. I've got blown in insulation up there as well. any concerns when the wire is approaching the soffit and it needs to travel through a little insulation where the roof and attic floor meet?
None that I can think of. What you're doing sounds pretty basic. I don't think you'll have any issues.
OK. just making sure I'm not going to burn the crib down. I appreciate all your input. Is there anything else I need to know or have we covered it all?
I think we're good. Just found the staples, stand by for link...
If you run into any snags, you can always come back here for more help from me, even if you rate now (no pressure).
Ha. Ok sounds good. I feel comfortable with this little project. Thanks again for all your help.
You'll nail it. You'll probably be surprised how easy it was, once all is said and done. You may even wonder why we're so expensive when you have us come out, LOL.
What would something like this cost me to have done by a professional?
I'm assuming about 2 hours of labor, at around (an average of) $90/hr.
Twenty dollars or so for material puts you in the $200 range.
Nice. I need to be an electrician. I'll pass that on to my wife when she asks what the hell I'm doing.
I understand. I used to get asked that a lot, when we first married. Not bragging, but I guess I finally proved myself to her, as she never asks anymore.
Ha. i'm not there yet. Hey thanks again. Take care.
My pleasure. Thanks for the opportunity to assist.