Light Bulb Query

[CoopJam]

Hope I'm posting my question in the right place. Sorry for the long story, but want to make sure there's no underlying issue.

So last night I turned on the bathroom light, and nothing - no power (no flash or bang, just nothing) Tried other lights on downstairs circuit and they were still working so thought it must just be the bulb. Didn't have any spare bulbs so took a bulb out of a table lamp which isn't used much and put it in the bathroom. Perfect, we have light.

For some reason, and I'm not sure why, I put the bulb that didn't work in the bathroom, into the table lamp and to my surprise the bulb worked. Thinking I was going crazy, I swapped the bulbs around a few times, always with the same outcome - both bulbs work in the table lamp but only 1 works in the bathroom ceiling light.

Bulb 1 is a Phillips energy saver 11w 230-240v bulb  (has been in bathroom for a couple of years working fine until last night it stopped working. But it still works in table lamp, although it does have a couple of dark patches on 2 of the tubes)

Bulb 2 is a Maxim 40w 240v incandescent bulb ( works in both bathroom ceiling and table lamp)

My question(s) is, how is it possible for bulb 1 to all of a sudden stop working in bathroom, yet it still lights up in a table lamp? Is it just a faulty bulb? Or does being an energy saver, or having a couple of black patches on the tubes, have anything to do with it? Or could there be a problem with the bathroom light or wiring? If so, why would 1 bulb work but not the other?

I appreciate any answers.

Thanks

J

 

[rapparee]

Bulb 1 is on the way out. The black patches are indicative of this. 

 

[ProDave]

Probably a dodgy lamp holder in the bathroom light fitting, and the very subtle differences in physical shape of the two lamps shows up the fault as one makes good contact, the other doesn't.

The table lamp has a different lamp holder that's better able to connect to subtly different lamps.

Or could be a failing connection inside the lamp. Try holding the table light upside down and see if it still works.

 

[rapparee]

Does the bulb make a high pitched hum by any chance in the lampholder

 

[CoopJam]

Probably a dodgy lamp holder in the bathroom light fitting, and the very subtle differences in physical shape of the two lamps shows up the fault as one makes good contact, the other doesn't.

The table lamp has a different lamp holder that's better able to connect to subtly different lamps.

Or could be a failing connection inside the lamp. Try holding the table light upside down and see if it still works.

I both bulbs appear to make good contact with the bathroom lampholder. Upside diwn table lamp still works.

Does the bulb make a high pitched hum by any chance in the lampholder

No high pitched humming from any bulb or lamp.

 

[kerching]

Also try the table light on its side.CFL lamps can be heavy and put undue load on the lamp-holders connections

 

[SPECIAL LOCATION]

Various reasonable possibilities can produce the symptoms described.....

a) The springy contacts inside the one lamp holder have lost some of their springiness

b) The solder lug contacts on the bottom of the one lamp are physically bigger than the other lamp.

c) Bit of a hi-res joint between lamp and lamp holder due to heat and/or moisture in the bathroom light fitting.

Or any combination thereof  + any others I forgot to mention.

Guinness