Rewiring a floor lamp or a table lamp is a great way for the new DIY Electrician to get some hands-on experience while working on a totally safe project. This project will teach you some essential skills i.e. the use of a simple continuity tester, how to test a lamp socket and switch for continuity, how to test a cord-set for continuity, and how to determine lamp cord polarization. These are skill sets that you will need when working on more advanced projects.
Restoring table lamps and floor lamps to like new electrical condition provides a completely safe environment for the beginner to learn essential electrical skill sets. Besides offering shockproof, hands-on learning, you can furnish your home with some really beautiful lamps found at garage sales and flea market for a fraction of what it would cost to buy lamps of equal beauty new. Restoring flea market and garage sale lamps is also a good way to start assembling your DIY Electrician's tool kit with quality tools.
Tools that you will need.
Supplies that you will need
Lamp rebuild kit (you could but the parts separately,but the kit is the best way to go. Kits come with a lamp cord-set that has a molded plug attached which eliminates your need to attach a plug to the Zip-Cord/Lamp-cord.)
As you can see from the above picture, the kit contains everything the you will need to restore your table lamp to like new condition. Kits are available for all styles of lamps, from the modern to the antique.
You will also need some glue for reattaching the felt to the lamps base.
Basic lamp circuit diagram
The electrical circuit diagram for a table lamp or floor lamp is about as simple as you are going to get, as you can see from this diagram.
The lamp circuit consists of four components—a plug (cord-cap), Zip cord (Lamp Cord), a switch, and a socket. With most table lamps, the switch is actually part of the socket. Separate switches and sockets are most often used with floor lamps.
Looking closely at this pictorial diagram, you will see that both the plug and the wall receptacle are polarized devices. The polarization of receptacles is easily identified by the length of a receptacles slots and the width of a plug's prongs. The wider of the two always connects to the neutral, or rounded conductor and the narrower of the two to the hot conductor. When wiring a lamp with a separate switch, the switch must always be inserted in series with the hot side of the line; that is a NEC requirement. The polarity of the Zip-Cord or Lamp-Cord itself is identifiable by the ridge molded into the insulation on the neutral side; the insulation on the Hot side is smooth. When connecting the Zip-Cord to the lamp socket the neutral side always connects to the silver colored terminal screw, which connects internally to the lamp socket's shell. The neutral terminals on all electrical devices is usually identified by its silver colored terminal screws.
Using the continuity tester.
Although you are replacing all the electrical components during this lamp restoration project, now is a good time to learn the proper way to use the continuity tester. The continuity tester has an internal battery that the power need for the tester to work, so it is always a good idea to test the battery first. To test the condition of the battery, simply connect the alligator clip to the tester probe. The bulb should burn brightly, if it does not light at all, or only shines dimly, replace the battery before using the tester.
Disassembling a table lamp or floor lamp is pretty straight-forward, so I will not use up space by giving step-by-step instructions here.
Using the continuity tester to test the lamp socket.
Disassemble the lamp socket as shown here.
To test the neutral side of the lamp socket, connect the Alligator clip to the lamp socket's screw shell and touch the probe to the silver colored terminal screw as shown here.
If the internally connections are good, the continuity will light up.
Next, check the hot side of the lamp socket and switch, if the socket has a switch built into it.
Connect the Alligator clip to the brass colored screw and touch the tip of the probe to vertical tab or button in the bottom center of the socket. If the switch and socket is good, the tester will light up when the switch is in the “ON” position. If it does not light up no matter what position the switch is in, the switch/socket is defective. If it does not go out when the switch is turned to the “OFF” position, the switch/socket is
To use the continuity tester to test a cord with a plug attached, just attach the Alligator clip to one of the plug blades and touch the probe to the corresponing end of the cord. If the circuit is continuous between the plug blade and the other end of the wire, the tester will light up. Tewst both sides of the plug and wire in the same manner.
Removing and replacing the lamp cord.
Carefully peel back the felt pad on the lamp base to expose the lamp cord.
Cut the lamp cord on both sides of the knot and pull the old cord out.
Insert the new lamp cord set through the hole in the base of the lamp. Allow enough wire so that it will extend at least six from the top of the threaded rod/threaded pipe before making a knot in it. The knot acts to keep the cord from being accidentally pulled out of the lamp.
With the socket cap in place, tie an Underwriter's Knot in the Zip-Cord where it enters the lamp socket cap. Here is how to tie the Underwriter's Knot.
The Underwriter's Knot is a secondary safety measure to prevent the cord from being yanked loose and causing a short circuit to occur at the socket shell.
Glue the felt pad back in place.
Types of plugs that may be used with Zip-Cord.
If you are rewiring a lamp, buy a cord-set, that is the lamp-cord with a molded plug already on it. Buying a cord-set saves both time and money. If you are just repairing a lamp that has a defective molded plug, here are two of the plug types that you may use to replace the old, defective plug with.
The snap-on plug is the easiest to install and the cheapest available. These plugs are UL approved for the purpose so they are safe to use, but I do not recommend them.
Any plug with screw terminals is far superior to the snap-on plug and are well worth the extra time it will take you split the cord, strip the ends and make up the connections under the screws. Omce again, note that the neutral side of the cord is connected to the silver screw and thehot side to the brass screw.
Test your finished lamp.
Screw in a light bulb, plug the lamp in, and twist the switch.
Congradulations on a job well done.