When you’re ready to start re-wiring your lamp, take time to choose the right bulb holder for the job. Here are the most important points to consider Before you buy:-
The old question of “what colour” do you want? The answer will pretty much decide the actual material that the bulb holder is made of and by effect decide if you need to earth the lamp or not. The decision will set how many cores the power cables needs e.g. 3 for earthed systems 2 core if not. (Admittedly there are suppliers of “chrome or metal effect” all plastic double insulated bulb holders that DO NOT need an earth connection, that feel well…. Like plastic, but can still be acceptable, you decide.) Look at our post on earthing your lamp for more information.
Now you know the colour, material and whether an earth is required, the next issue is attaching a cable. Do you need an earth, does it need to be inside the bulb holder or connected to the outside?
Obviously if no earth is required then it’s not an issue, but if it requires one how are you going to route the cable? An anglepoise arm is very thin, so running a 3 core flex to an Internal earth post inside the fitting will be very difficult. A 3 core cable is generally too fat to slide inside the arm, which means getting a wire to the inside of a bulb holder and attaching the other end to the plug will not be an easy option.
However there are work rounds, early Anglepoise themselves attach an earth point on the base then fit a double insulated bulb holder “a belts and braces approach that I like”. You could as many do, take a cable from an external earth post then attach it to the lamp shade by screw or eyelet clamped by the bulb holder its self.
Another method that works well on a chrome or polished metal finish lamps is to not fit an earth wire at all to the holder. The bare metal sections are all incontact throughout all parts of the lamp, from holder to shade to arms etc all the way via the earth bolt to plug. (please note that this system of earthing only works if all parts are un-painted at point of contact) The earth fault current cannot pass through thick layers of electrical insulating paint and would much rather go through your wet low resistance body when you touch the light, which generally is a bad thing….
“So consider, does it need an earth (metal holder), can you get a earth wire to the holder, where will it be attached to and how?”
What size hole is in the lamp shade? Standard “old school” was an inperial more modern is metric. Check your lamp shade, if its non current standard can it be adjusted, or an adapter plate made to match a more modern blub holder? ? If it cannot be adjusted then you will have to find a bulb base type with similar shade ring diameter which may dictate the type and size of bulb holder.
How is the bulb holder attached to the lamp? Does it need a “screw on” thread at the base, or does it need a cable grip? If your lamp is an Anglepoise or the type that has the lamp shade that is fixed in place and the bulb holder is supported by the shade then a Cable grip type is recommended. (The cable grip protects the electrical connections inside the bulb holder by preventing the outer sheath of the cable being pulled out of the lamp fitting). You can use a “threaded Base” type in an Anglepoise if you’re not too worried about seeing the threads at the cable entry. (fitting a cable grommet into the threaded hole can help hide the problem).
What type of bulb do you want to fit? The heat generated, colour temperature, size, shape, current load and electrical fitting type are all factors you should consider. Take a look at our Light bulb guide and ensure that your lamp has a bulb holder suited to your chosen Light Bulb. More importantly is that your light bulb is suitable for your needs and Lamp Safety.
Extra safety feature “Bulb contact covers”. Safety Bulb holders have physical shields that pop out and cover the bare electrical posts that protrude from the bottom of the bulb holder and makes the electrical contact. If you are changing a blown bulb and have forgotten or don’t know the dangers of electricity (child etc) the exposed posts can electrocute you, if your fingers touch them. These safety holders prevent all but the most determined of fingers from accidental contact and electrocution. They are more expensive but as ever how much is your life worth to you?
Hopefully armed with the above considerations, your are in a position to make an informed choice. Always remember when rewiring a lamp that electrical safety is paramount, always ensure your competent to do the job, use the correct material and test that it is safe to use. Relight Lamps always PAT test all our lamps, we suggest you do too.