Table lamps

Faulty table lamps, desk lamps and floor-standing lamps, often cherished items, are usually quite easy to repair and spare parts are available. Owners are sometimes confused, though, by the range of different types of bulb that are available.

Summary

People are often very attached to a vintage table or desk lamp that maybe belonged to their grandmother, or which they took a fancy to at a car boot sale. Others are relatively new and have just stopped working. These can nearly always be fixed. Search online for table lamp spares. You should be able to find suppliers from which you can obtain all the parts you need, including brass fittings, switches, and old style cotton covered wire. You just need a very basic understanding of electricity and how to wire a plug in order to do the job safely.

Check for a frayed or loose cable which could be dangerous. Using a test meter, check the continuity of the wiring from the plug, through the switch to the lamp holder.

Modern LED and electronically controlled lamps can be a harder but you can still check for basic faults. You may be able to bypass a faulty electronic control and add an in-line switch to the flex instead, though not if the same electronics is dropping the mains to a low voltage for a LED lamp.

A separate page demystifies the several different types of light bulb, and their many shapes, sizes and bases.

Safety

An electrical safety test is highly recommended, including a visual check, both before and after a repair, especially for an older item.

As with any mains operated item, it's a good idea to have the plug on the bench in front of you before starting to work, so you can be certain you didn't forget to unplug it.

Fault finding

The first and most important task is to inspect the electrics. A frayed lead, cracked plug or cracked or faulty switch must be replaced. Check the fuse with a multimeter on a low resistance range.

If the lamp uses a filament bulb, check this too with a multimeter. A faulty low energy (compact fluorescent or LED) bulb can only be positively identified by substitution.

If the lamp uses a mains voltage bulb (of whatever sort), test continuity between the plug and the bulb holder with a multimeter on a low resistance range. To do this, touch one probe on one of the pins of the plug (but not the big earth pin) and see if you can get a zero reading by touching the other probe on one of the contacts in the bulb holder. The switch may be off. Try it in the other position of the switch. Now repeat with the probe on the other pin of the plug. If you can't get a zero reading in either case then there is a break in the wire, or the switch is faulty.

Lamps using a low voltage halogen or LED bulb have a transformer or an electronic equivalent in the base. This is harder to test but you should still be able to test for continuity between the plug and the transformer and between the other side of the transformer and the bulb. Check for any signs of overheating, or for a bulging or leaking electrolytic capacitor.

Some such lamps have touch controls for on/off or for dimming. These too are harder to diagnose beyond simple continuity checks and a visual inspection for obvious faults.

Repair

A wide range of spare parts for lamps is available online, including brass or plastic lamp holders and fittings, switches and decorative or fabric-covered flex for an authentic restoration of a vintage lamp. Simply search online for "lamp parts" or "lamp fittings".

Getting inside a table lamp with a decorative base such as glazed porcelain is sometimes a little tricky. A porcelain base may have a paper or felt bottom to prevent it scratching a polished surface, and you may need to remove this to get inside. Sometimes you may have to unscrew the top. You may have to pull the lead from the plug into the base in order for it not to get impossibly twisted in the process.

The lamp holder may need replacing. This may be plastic or brass, and with or without an integral switch. Other brass fittings such as threaded tubes and nuts to fit them may also need to be replaced.

A brass lamp holder should have a screw terminal for the attachment of an earth wire. It's very important that this is connected as otherwise a fault could be lethal.

External Links

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