How to deal with walls?

Running cable through finished walls or ceilings is a nuisance. Once you’ve determined that a circuit can be extended or a new one added, you should plan the circuit’s route and figure out the least-disruptive route for the cable. An existing circuit can be extended from an electrical box provided that …

• The box is sized to accommodate the additional cable.
• The box isn’t at the end of a switch loop (an end-of-the-run switch).
• The box isn’t a switch-controlled receptacle (unless you want the added device to be controlled by the switch as well).

Your best and easiest route is through an unfinished basement or attic, If you’re drilling into a crawl space, place a flashlight over the top of your drilled hole and turn it on. This makes it a lot easier to find the hole when you’re crawling under the house. If you have several holes to drill, insert a piece of scrap neutral wire into the hole; you’ll be able to see its white insulation more easily and mark each hole. It isn’t always easy to determine the location of a box when you’re up in an attic or down in a basement. From an approximate location in an attic, you can drill a very small hole on the outer edge of the wall’s top plate through the ceiling below and then poke a section of wire hanger or scrap wire through. From the room below, you can locate the necessary drilling location, go back to the attic, and adjust your coordinates. From the basement, you can drill a pilot hole from above (if you’re adding a receptacle) through the sole plate or bottom plate of the wall using a long, narrow twist bit. Then drill the larger hole from below. If the floor is only covered with subflooring material such as plywood, you can use your drill or drive a 16d finish nail through a location near the base of the wall where your new box is going in, looking for the nail down below. If you don’t object, you can do the same through carpet; just be sure to place the nail near the very edge of the baseboard and use a nail set to pound the head below the surface of the carpet
What if you have wood flooring? If you cannot accurately determine where to drill from the basement, drill the smallest hole possible (with a drill bit about four inches long) near the edge of the baseboard. Push a piece of wire through the hole so you can find the location in the basement. A piece of scrap conductor from your NMB cable will work just fine. At the end of the job, fill in the hole with a putty stick in a color matching the floor stain.

How Much You Can Keep?

Basically, you can retain any and all safe wiring and devices. An electrical system will do what it’s designed to do and will do so reliably until you extend a circuit or the system beyond its design. You should remove or replace the following:

• Any corroded or damaged wiring
• Wiring that has not been installed properly (such as wire running along the bottom edge of an exposed joist rather than through holes drilled in the joist)
• Devices or fixtures that render a circuit unsafe
• Conductors that are the wrong gauge for their circuits
• Any cable rated for interior use but installed outdoors You might be getting more than you bargained for if your system has been repeatedly altered over the years.

If additions have been made based on convenience (“Hey, look! I found a couple of wires.”) rather than logic, you could end up with an odd variety of lights, receptacles, and other fixtures all over your house. It might be best to run a new circuit or two to cover all these miscellaneous runs if you’re not already rewiring the whole house.

Mixing Old and New Wiring

You can connect new cable or wire to existing cable or wire if you follow these rules:

• All connections must be made inside an electrical box. The one exception is knob-and-tube wiring, which is the only electrical system that can be spliced in the wall. To do so, you must solder the conductors or use a mechanical splice such as a split bolt; a wire nut is not sufficient.
• Junction boxes must be kept accessible. They cannot be covered up.
• Don’t change the wire gauge. (New wire has to match existing wire.)
• Be careful not to overextend the circuit by adding more loads than it’s designed to handle.

Knob-and-tube wiring doesn’t lend itself to easy identification of the hot and neutral conductors. You might have a junction box or device box packed with wires. Identify the hot lead the same way you would identify it in a less-crowded box:

1. Identify the circuit and turn off the power at the panel.
2. Check the connections with a voltage tester to confirm that the power is off.
3. Carefully remove any tape or wire nuts from the connected wires (those running back toward the panel).
4. Mark the wires so you know which ones were connected to each other.
5. Separate the wire ends so they’re not touching each other or the sides of the (metal) box.
6. Turn the power on at the service panel and test the wires one at a time until the hot lead lights the bulb on the tester.

Mark this as the hot line conductor. Messy junction boxes often indicate that a device or fixture was added without a lot of consideration as to its effect on the circuit. Your best bet is to confirm whether the circuit can or cannot safely support the addition and then deal with it appropriately. It might be that all you’re looking at is an unkempt, but safe, series of connections.

Messing Around With Old Wiring

The easiest residential wiring to work with (short of metal conduit, which you’ll never find in a typical home) is grounded NMB copper cable. It’s newer than knob-and-tube wiring, the insulation is tough plastic, and you have none of the safety dilemmas that you have with aluminum wiring. If your electrical system was recently installed and inspected, it should be simple to trace circuits and calculate loads as you plan your additions and changes.
Regardless of the age of your system, you’ll have to tally your amperage usage for the total system as well as for each individual circuit affected by your work. Simply looking inside your service panel and counting the breakers or looking for an empty space to install a breaker isn’t enough. Wiring or changing your system generally means doing some damage to your house.
The larger the access holes and openings for boxes, the more repairs you’ll have to do. Your working goal should be to keep the repairs and patching to a minimum. As you can see, there’s more to electrical work than simply deciding to add a receptacle and running some wire.

Sock It to Your Socket

In addition to damaged plugs, lamp sockets also are a regular culprit when a lamp won’t light. The socket itself doesn’t wear out, but the switch does. Several types of replacement sockets are available including …
➤ Pull chain.
➤ Twist knob.
➤ Push lever.
➤ Remote.
It’s easiest to replace your existing socket with one of the same style. Follow these steps to inspect and replace your socket:

1. Unplug the lamp.
2. Look at the outer shell of your socket. If it says “Press,” you can squeeze the socket and pull it out. If not, your socket is held in by screws, or the socket and harp (the frame for the lampshade) are secured to a threaded metal tube that runs the height of the lamp and is bolted at the base.
3. With the socket removed, check the wire connections at the screw terminals. If they’re tight, loosen the screws and remove the wires.
4. Test for continuity by placing your tester’s clip on one prong of the plug. Put the probe on the black wire and then the neutral wire. Put the clip on the other prong and repeat the test. If the tester’s bulb doesn’t light for either prong, you’ve got a bad cord and plug, and they’ll need to be replaced.
5. When you’ve determined that the socket is the source of your lamp woes, replace it with a new one with matching volt and amp ratings. Remember to attach the neutral wire in the ribbed or ridged insulation to the silver screw terminal and to attach the black or hot wire to the brass screw terminal.
6. Slide the insulating cardboard sleeve and outer shell over the socket and install in the lamp snuggly. (It fits into the lamp cap.)
7. Reinstall the harp, shade, and bulb and then test.

Round-Cord Plugs

These are made for heavier-duty loads and loads needing a grounding plug. The terminal screws also are more substantial than on smaller, flatcord plugs such as those on lamps and radios.
Follow these steps to install a round-cord plug:

1. Cut the cord end clean with lineman’s pliers or a combination tool.
2. If there’s an insulating disc with the new plug, remove it.
3. Pass the cord through the clamp on the rear of the plug.
4. Strip two to three inches of insulation from the round cord and 3⁄4-inch of insulation from the hot, neutral, and grounding wires. Tighten the clamp.
5. Take the black wire and the white wire and tie an underwriter’s knot as close as you can to the cut edge of the insulation on the cord.
6. Wrap or hook the end of the black wire around the brass terminal screw going in a clockwise direction. Do the same with the neutral wire and the silver terminal as well as the grounding conductor and the green terminal.
7. Tighten the terminal screws securely. Make sure the wires are not touching each other.
8. Install the insulating disc.

Bugged by Bad Plugs

An intact plug has straight prongs, a solid casing, and a cardboard insulating faceplate or disc (unless the entire plug is solid plastic). If the prongs are bent, the casing cracked, or the faceplate missing, replace the plug.
Plugs come in a variety of styles including …

➤ Flat-cord plugs.
➤ Quick-connect plugs.
➤ Polarized plugs.
➤ Round-cord plugs.

The easiest plug to install is a quick-connect plug. The prongs of the quick-connect plug can be removed from the casing by squeezing them together. By spreading them, the lamp cord can be inserted. To attach a quick-connect plug, squeeze the prongs together and slide them back into the casing. You don’t have to do any work on the wire; just follow the instructions on the package. Be sure the plug is rated for the load to which you’re attaching it. (You won’t get away with a quick plug on a heavy-duty portable appliance, for example.)
To replace a flat-cord plug, disassemble the casing on the new plug, pull apart the two halves of the lamp cord to the length of two inches or so, strip the insulation off the ends of each half, wrap the wires clockwise around the screw terminals, and reassemble the casing. The quick-connect plug is the easier of these two to install, but it’s not the best choice for a lamp that’s unplugged often.