Table lamps and floor lamps are relatively simple devices consisting of a plug, socket w/switch (with some floor lamps the switch may be separate from the socket) and a length of two-conductor lamp-cord (wire). Reconditioning lamps is a great skill and confidence building project for the new DIY electrician because there is absolutely no chance of electrical shock.
Reconditioning table lamps and floor lamps require simple hand tools and a Digital Multimeter. A good digital Multimeter is the cornerstone on which every DIY electrician’s tool kit is built. One can spend less then ten dollars to several hundred dollars on a digital Multimeter but I recommend Radio Shack’s Model: 22-813Catalog #: 22-813 23-range, auto-ranging meter which sells for $29.99 at most Radio Shack stores. If there isn’t a Radio Shack retail store in your area, you can order it from their online site. Although I will explain how to use this meter for the project at hand, the first thing that you should do when you get your new meter is to read the instruction manual that comes with it from cover to cover. This manual contains a wealth of valuable information about the meter, how to use it to take various measurements (Voltage measurements, current measurements, and resistance measurements, etc.), and it tells you what not to do to not damage the meter. Always read the instruction manual for any new piece of test gear that you acquire. I still do that even after having worked with electronic test instruments for close to fifty years.
Hand tools needed
2. A small, Philips screwdriver
3. Pliers
4. Needle nose pliers
5. A pair of diagonal pliers (wire cutters)
6. A pair of wire strippers
7. A soldering gun or soldering pencil
The supplies that you will need are:
1. 18ga lamp-cord
2. Polarized plugs
3. Lamp sockets
4. Switches
5. Rosin core solder
6. Electrical tape
Troubleshooting a lamp that doesn’t work.
Before I explain how to recondition an older lamp whose wiring has deteriorated from age, let’s take a minute or two to discuss troubleshooting a newer lamp that doesn’t work.
First and this may sound silly, but check to make sure that the lamp is plugged in. You’d be surprised at how many service call I’ve made where the only problem was that the appliance was unplugged or the CB (circuit breaker) had tripped. If it’s plugged in, check the bulb. You could check the bulb with your meter but for now replace the bulb with a known good bulb. If it still doesn’t light, check the receptacle that it’s plugged into for voltage.
Checking a receptacle for voltage
1. Referring to page 12 of your operating manual set your meter up to take an AC (ALTERNATING Current) voltage reading using Automatic Ranging.
2. Insert the red and black probes into the two vertical slots of the receptacle where the lamp was plugged in. Make sure that you check both halves of the receptacle because one side may check good while the other side is dead. If voltage is present, your meter should indicate a nominal 110-Volt.
3. If the side of the receptacle where the lamp was plugged in is dead but the other side checks good, check to see if you have a switched receptacle circuit. Some receptacle circuits are designed to control table and floor lamps by a wall switch. Make sure the switch is in the “on” position. If it isn’t a switched circuit then you need to replace the receptacle.
4. No voltage at the receptacle, check for a tripped CB or blown fuse. Reset the CB or replace the blown fuse with the appropriate rated fuse.
5. If there was voltage present at the receptacle and the bulb is good, we need to troubleshoot the lamp itself.
Procedure
1. Unplug the lamp.
2. Remove the shade, unscrew the bulb, and remove the wishbone assemble from the socket.
3. Using the flat blade screwdriver, pry the brass shell free of the socket’s base.
4. Separate the shell and its cardboard insulation liner from the socket assembly.
5. Referring to page 16 of your meter’s manual, set the meter up to check “continuity.”
6. Now check for continuity between both sides of the plug and the silver and brass screws on the lamp socket. You should a “beep” on each side. If you don’t, there is an open circuit on that side. A bad plug or a break somewhere else in the lamp cord between the plug and the socket may cause an open circuit. If the lamp uses a switch separate from the socket, remove the switch and check for continuity to the switch and from the switch to the socket before condemning the plug or cord.
7. To check continuity to the switch, simply move the probe from the brass screw on the lamp socket to the plug side of the switch. If this checks, good check the continuity between the socket and the socket side of the switch. If this checks good, then the switch is defective and needs to be replaced.
8. If there still isn’t any continuity between the plug and the switch, then the problem is in the plug or cord. Most plugs are molded plugs so simply cut it off the cord using your diagonal cutters.
9. Separate the end of the lamp cords and strip the insulation back between ½” and ¾”. Repeat your continuity checks. If the continuity now checks good, install a new plug on the cord making sure that you connect the wire on the ribbed side to the neutral side of the polarized plug.
10. If there still isn’t any continuity, there’s a break somewhere else in the lamp cord and you need to replace it.
11. The easiest way to replace a lamp cord is to remove the socket, tie the new lamp cord on to the old one, and use the old one to pull the new one through the lamp housing.
12. Install a new plug and reconnect the lamp socket, connecting the silver tinned wire or the wire on the ribbed side to the silver or neutral screw and the copper wire or the wire on the no ribbed side to the brass screw on the socket.
13. If the initial continuity checks were good then the problem was the socket assembly and you needed to replace that.
Helpful hints
1. Before connecting new wire to the lamp socket and plug, tin the leads. Tinning the leads simply means coating them with solder so they can be shaped to fit tightly on the screws. To tin the leads heat them from the bottom side with a soldering gun or pencil and then touch the Rosin core solder to the topside of the wire. The solder will flow evenly over and around the wire. Never apply the soldering gun or soldering pencil’s tip to the solder.
2. Using the needle nose pliers form a loop in the tinned ends in a clockwise direction. This loop should extend between ½ and 2/3rds around the screws on the socket and on the plugs. By placing them in a clockwise direction, they will twist into the screw as the screw is tightened instead of twisting out from under the screw, which would happen if they were placed in a counterclockwise direction.
Reconditioning a lamp
Actually, reconditioning a lamp is simply replacing all it electrical components and after reading the above you already know how to do that.
What if the receptacle was bad, you’re asking? Well I’ll cover replacing receptacles in another article.
