Home Improvement : THE ONE-HOUR PROJECT : Shedding Light on Replacing Electric Plugs : Sooner or later, chances are you are going to have to repair one.
Generally, electric plugs last a long time, but even they have to be replaced sooner or later. Fortunately, plug replacement is probably the easiest electrical job you can tackle, next to changing a light bulb.
Zip cord, that lightweight lamp cord that looks like two wires running side by side, will take a clamp-on replacement plug you can install in about a minute. You can get one of these plugs at any hardware store. While you are there, get two or three. They’re handy to have around.
To use a clamp-on plug, start by cutting the cord off square across the end. There’s no need to strip the wire, and in fact, no conductor should stick out beyond the insulation.
Next, slit the wire between the two cords for a distance of one-quarter inch. You can do this with a knife, or, if you have strong fingers, just peel the two wires apart.
Now open the plug’s clamping lever, slip the end of the cord into the opening in the side of the plug, push it as far as it will go and snap the clamping lever shut.
That’s it. Test your handiwork to make sure it functions.
If It Doesn’t Work
These clamp-on plugs have little pins inside that are meant to pierce the insulation and make electrical contact. Every now and then, they don’t. This is usually because you didn’t insert both conductors all the way into the plug.
If this happens to you, open the clamping lever, pull the cord out and examine the ends. If they appear mangled, cut them off and start over. If the ends seem OK, just reinsert and try again. If the plug still doesn’t work, try another one. The pins inside may be bent.
Clamp-on plugs should only be used with lightweight cords. Usually, 18-gauge is the heaviest they will handle. If your cord is heavier than that, it probably won’t fit a clamp-on plug. In that case, you’ll need something heavier.
If you are replacing a grounded “three-prong” plug, be sure to buy another grounded plug. If you are replacing a two-prong plug, get a two-prong replacement, preferably a polarized type. A polarized plug will have one prong or blade wider than the other and it does a better job of protecting you from electrical shock than an unpolarized plug does.
Unfortunately, if your house is wired with old-fashioned, unpolarized, two-hole receptacles, you won’t be able to use polarized plugs. In that case, it would be a good idea to have an electrician come in and replace all your old receptacles with modern grounded outlets.
OK, if the end of your cord is still in good shape, go ahead and connect it as described below. But if the end of the cord is shot, first you’ll have to cut back to sound wire, then strip the wire. Here’s how:
Tie Underwriters’ Knot
If the wire has an outer jacket, remove about 3 inches of it. Use a knife but be careful not to cut the insulation around the conductors.
Next, remove the fiber cover from the business end of your plug, slip the cord into the back of the plug, and tie the Underwriters’ knot shown in the sketch. This knot forms a “gob” of wire that prevents you from straining your connections the next time your kids yank on the cord. Tie the knot loosely as shown, then pull the conductors to tighten the knot up, right against the point where the conductors separate from each other. When the knot is tight, pull on the cord to seat the knot firmly in the body of the plug.
Next, run the wires to their respective screws to see how much insulation you’ll need to remove from each wire. Which wire goes to which screw?
If you are using an unpolarized two-prong plug, it doesn’t matter.
If you are using a two-prong polarized plug, the black wire goes to the brass screw or to the narrow prong, and the white wire goes to the silver screw or wide prong.
If you are connecting a zip-cord without color-coded wires, examine the insulation. One wire should have ribbed insulation. Connect this wire to the wide blade and the smooth wire to the narrow blade.
Stripping the Wire
If you are installing a three-prong plug, the black wire goes to the brass screw, the white wire to the silver screw and the green grounding wire to the green screw.
After running each unstripped wire to its screw, you are ready to strip. How much insulation should you remove? You want each wire insulated right up to the point where it reaches the screw. Beyond that point, strip the wire bare. This is easiest with a wire stripper but you can also use a knife. Just be careful not to cut the conductor.
Next, bend the stripped end of each conductor into a little clockwise loop. If the conductors are stranded rather than solid wire, twist the strands tightly together before forming the loops.
Now slip each loop around its proper screw--making sure the loop wraps clockwise--and tighten each screw down snug. Replace the fiber cover plate that you removed earlier and the repair is complete.
