How do we change this light bulb in pendant light fitting - seriously


Postby Chris2015 » Sat Jan 03, 2015 12:58 pm

New member here, so, greetings. I’ve just moved into an old house, to be rewired in the spring. Most of the existing wiring is at least 30 years old. The bulb in an old pendant light fitting has blown, but neither my partner nor I can figure out how to remove it. Neither can alleged handyman Dad! The bulb has a Woolworth brand on it so I guess it’s older than both of us. We’ve managed to partially unscrew the white collar holding the bulb, but can’t dislodge the bulb itself. Pushing it into the socket and trying to rotate the bulb, like a bayonet fitting, doesn’t do anything. How do we remove the bulb, please? Thanks. :-)
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Postby proptech » Sat Jan 03, 2015 6:38 pm

HI Chris2015

I expect that this is a normal bayonet bulb, bur the soldered contacts have softened. Best thing to do is to replace the plastic lampholder complete with the bulb, available in any DIY store. Power off before you start.
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Postby Chris2015 » Sun Jan 04, 2015 12:39 am

Thank you, we'll do that. We were thinking it might be some kind of age-related rot.
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Postby ericmark » Sun Jan 04, 2015 12:30 pm

As proptech says bulbs which have been in the holders for ages do suffer from solder creep where the spring pins form dimples in the solder.

In the main caused by a bad connection somewhere on the pins likely where the pin slides up and down. Although clearly with power off you can first try with good glove to protect from glass to put extra effort and if the glass detaches you can use long nose pliers and twist out the shell likely the problem will return.

So better to replace bulb holder normally only two connections and does not matter which way around.

One problem I have seen is where the fuse/MCB/RCBO has been changed from 5 or 6 amp and a 10 or 16 amp one fitted instead. Although it complies with regulations up to 16A when a bulb blows it can have ionisation of the gases inside it (Large flash as it blows) this will often take out a 5A fuse or 6A trip before any damage but with a 16A trip it can melt the solder on the bottom of the bulb welding it in position.

It was common with silly 50mm spot lights to lift MCB size as they used that much power, this is really only allowed if no ceiling roses are used as the rose is used as a junction box and only rated at 6A but it was still done.

In theroy every bulb should have a built in fuse to stop ionisation damaging contacts or tripping the MCB but in practice often not there. I had a lot of problems with Ikea compact fluorescent bulbs welding into bulb holders when they failed.
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