Here is a question that I haven't been able to get a good answer too. What is the proper method to run an electrical line off of an existing outlet if the outlet already has a line in and a line out (ie, it's wired in series)? Is pigtailing the wires acceptable?
I pigtail EVERY receptical unless it's at the end of the run. Period. Yep, from everything I was taught it's acceptable. While you're at it, pigtail all the connections so they're all in parallel. Look at it this way, if something happens to that outlet afterwards all the rest don't fail down the line.
You can have a souce line enter a box and a number of feed lines exit a box. The size of the box will determin how many are allowed to come in and out of a box. All the wires are to be tied together with wire nuts. White to white, black to black, ground to ground. One set of wires the (pigtail) is a short wire that goes from the wire nut to the plug. It is also better to attach the wire to the plug with the screw and not the push in clamp thing on the back.
Hope that makes it a bit clearer if not then I need to draw a picture.
If you can do it, pull out your box and replace it with a deep box. They are made especially for having extra room for wiring in back.
The cost of those boxes confuses me. I am looking at rewiring my garage by putting in all my new boxes, then run the wire, followed by removing the old wiring (Some of the current boxes will just be moved, or just wired into the new circuit as I go.). I went looking at the plastic boxes that nail in for new work. Single gang boxes are nineteen cents each. A double box is a full buck. Seems quite a difference in price for a little more plastic.
One other thing not mentioned already is with regard to the wire you should use. You should never use 12ga or 14ga because that's all you have!
If the circuit is a 15A fuse or breaker, the wire in use is most likely 14ga (but could very well be 12ga). For 20A lines it should be 12ga from panel to receptacle.
It is VERY important that you match the wire to the same gauge as everything else on the circuit. If you splice in some 12 ga on a 15A circuit that is wired with 14ga, someone, someday may add a 20A plug receptacle to that 12ga wire you install. On the other hand. . . on the panel end if someone sees 12 ga on a 15A circuit that's been tripping, they may 'upgrade' the breaker to a 20A, creating a fire hazard for any 14 ga that had been added to the circuit . . . even though it was safe for the 15A there at the time.
To sum up when retrofitting a circuit . . . always match what's there . . . never assume you'll be the only one to ever work on it (or that you'll remember what you did the next time) . . . and don't use something bigger just because it's all you have on hand.
When it comes to
woodworking and buying
tools, I always think back to
my grandfathers advice on
golf . . . "it's not the arrows,
it's the indian.''
> I went looking at the plastic boxes that
>nail in for new work. Single gang boxes are nineteen cents
>each. A double box is a full buck. Seems quite a
>difference in price for a little more plastic.
That one got me too . . . but I did use those when I wired the overhead receptacles that the 4' shop-lites plug into.
For everything that gets plugged and unplugged, I use the 'handy' boxes . . . the little rounded metal ones . . . very easy to work with and no sharp edges. They actually come in (less expensive) plastic now as well . . .
I wont use handy boxes for anything. They're simply too small to hold any wiring and a receptacle and because of that can result in broken wires etc. I use deep plastic boxes for most things except where they wont physically fit. Last rooms I wired had 2x2 furring strips and we used 4" metal boxes with single outlet covers rather than handy boxes because they afford over twice the space to put wires and wire nuts. Also to save space cut the outer sheath so that only 1/2" protrudes into the box. Somewhere I have a list of the cubic inches each item in a box takes up, once I find it if anyone's interested I'll post it. You can then compare what you need to put in there to the cubic inch capacity listed on the box.
I guess I'm lucky. Whomever built my house used 12 guage for everything. I've since done a bit of electrical and had some done for me and used 12 for all of it. It can be hard to work with, but I like doing things overkill :)