One lamp bulb blows the other doesnt

[tom_cairns]

I bought a tall and short version of the same lamp from John Lewis. The tall lamp has blown three bulbs in 6 months, the short one none (as you would expect). John Lewis replaced both the lamps about 6 weeks ago and the tall lamp has just blown again. Any ideas? Could it be the wiring in the actual socket?
Thanks
Tom

 

[JohnW2]

Almost certainly just 'bad luck'/co-incidence.

What sort of lamps/bulbs are they, and do they bear the name of any manufacturer that you've heard of?

Kind Regards, John

 

[tom_cairns]

Really? Identical bulbs in the lamps, new replacement lamps and still the tall one in the same location has blown 4 bulbs in less than a year? I will check the bul make in a bit and let you know.
Thanks
Tom

 

[JohnW2]

Really? Identical bulbs in the lamps, new replacement lamps and still the tall one in the same location has blown 4 bulbs in less than a year?

Indeed - if it's bad luck it's probably very bad luck - but don't forget that if the replacements all came from the same place (John Lewis) it's not impossible that they all came from the same duff batch.

Unlikely though the 'bad lucki is, it is even more difficult to understand how anything to do with the lights (assuming they are similar but just different heights) could affect the lamp life. Only if they differed appreciably in design in such a way that the lamps in the taller light got much hotter would there possibly be something to think about.

I will check the bul make in a bit and let you know.

Thanks. With some of the nameless (or 'unknown name') Chinese imports, 4 failures in a year might not be all that unusual

Kind Regards, John

 

[Deleted member 18243]

Is the tall lamp in an area subject to vibration or to being bumped into by children or pets?

 

[flameport]

Quartz halogen lamp which persons have installed with their greasy fingers after the initial one broke?

 

[333rocky333]

Is it a screw in lamp fitting, sometimes the lampholder is poor quality and a poor connection to the bulb causes heat and premature bulb failure

 

[tom_cairns]

andy - it is next to the stairs so thats a possibility
rocky - it is a screw fitting but it is identical to the other lamp
John - regardless of where the bulb is from I have used the same bulbs in both lamps and I suppose I was really asking if the actual socket could be a source of the problem - but thinking about it, the tall lamp I had previous to this one from Ikea did not suffer the same problem.

Looks like bad luck it is!
Thanks everyone

 

[JohnW2]

rocky - it is a screw fitting but it is identical to the other lamp

Fair enough, but Rocky's point was that, particularly if a screw fitting, it's possible that, although identical to the one in the other light, the socket in the tall one is faulty in such a way as to make the lamps overheat.

John - regardless of where the bulb is from I have used the same bulbs in both lamps ...

If I understand correctly, it's not quite as simple as that. I imagine that both of the lights probably 'came with' a lamp/bulb, quite possibly put in the packaging by the light manufacturer, whilst the replacements have presumably come from John Lewis's stock of lamps/bulbs - maybe a different make and, even the same make, unlikely to be the same batch as the originals. If I understand correctly, the lamp in the small light is still the original. If the first failure in the tall lamp was just 'one of those things', all the subsequent replacements (and failures) will have come from JL's 'lamp stock' - hence probably different batch (and maybe even make) from the original in the tall lamp and the one that's always been in the small lamp.

... and I suppose I was really asking if the actual socket could be a source of the problem

As above, per Rocky's point, it's not totally impossible.

Looks like bad luck it is!

As you know, that was my first suggestion, and I still think it's the most likely explanation. However, none of the other possibilities that have been mentioned is impossible.

If it has just been (very) 'bad luck', I hope that your luck improves!

Kind Regards, John

 

[333rocky333]

Thanks john.
That was my point.
I recently had a freind with a 5 arm chandelier from B and Q, the holders obviously all the same, but the one same holder blew lamps about every 2 weeks, we swopped that holder and since then no issues, despite it looking ok.
Whether it was a weak spring on the connection, or a slightly loose or poor connection we will never know.
I quess the ops reference to the "socket" is meaning the 13amp mains socket, id say possible, but the least likely, though if the plugtop is not a moulded type, though unlikely to cause the issue stated, it may be worth checking the tightness of terminals inside that.

 

[JohnW2]

Thanks john. That was my point. I recently had a freind with a 5 arm chandelier from B and Q, the holders obviously all the same, but the one same holder blew lamps about every 2 weeks, we swopped that holder and since then no issues, despite it looking ok. Whether it was a weak spring on the connection, or a slightly loose or poor connection we will never know.

Yes, it happens.

I quess the ops reference to the "socket" is meaning the 13amp mains socket, id say possible, but the least likely, though if the plugtop is not a moulded type, though unlikely to cause the issue stated, it may be worth checking the tightness of terminals inside that.

Oh - I assumed he was referring to the lamp holder. I have to say that I find it pretty hard to believe that that anything to do with the 13A plug could result in what the OP has experienced. Only if the connections in the plug were so loose that the light was constantly 'flashing on and off' (which the OP would have noticed!) can I see that it could affect lamp life. However, as always, I suppose that nothing is impossible,

Kind Regards, John

 

[Mikefromlondon]

Interesting, logically you would think if both bulbs are the same and wired up same, same type of holder except one being a taller lamp, there should be no reason why the taller oen fails more often than the short one. of course vibrations, lose connections, slight arching at contact point or even arching on the switch itself may contribute to a shortened bulb life,
however, there are other factors that OP has not mentioned and these are;

1. Does the bulb fails when you just tried to switch on?
2. Or has it suddenly failed when it was already switched on for a while.
3. how often is the taller lamp switched on daily compared to the shorter lamp.

only then you could reach a slightly more explainable scenario, since most incandescent types of lamps fail on first switching on, and you have to be very unlucky if you just happen to hit the ON/OFF button from off to ON at a precise time when your mains voltage was looming at highest peak well above the nominal 230V ac, i.e. it may have shot up to say 245V !
In UK the mains can have an upper limit of 10% of nominal 230v hence it can often reach up to 253V and if you happen to strike your switch at the highest peak of the sine wave as well as slightly higher than nominal voltage it can pop your lamp. And sure you don't switch both lamps simultaneously, in many cases lamps failing on switch on also pops your MCBs.
I found 60watt candle shaped bulbs had worst life expectancy in my chandeliers, i have stopped using those and now use energy savers, they can last for years.

 

[333rocky333]

Oh - I assumed he was referring to the lamp holder.

I was unsure at first, mind you it later seemed confirmed by

"I was really asking if the actual socket could be a source of the problem - but thinking about it, the tall lamp I had previous to this one from Ikea did not suffer the same problem."

 

[JohnW2]

I was unsure at first, mind you it later seemed confirmed by "I was really asking if the actual socket could be a source of the problem - but thinking about it, the tall lamp I had previous to this one from Ikea did not suffer the same problem."

Yes, fair enough, I hadn't taken that in. However, I remain of the view that it's incredibly unlikely that anything to do with the (13A) socket could possibly result in what the OP has described!

Kind Regards, John

 

[tom_cairns]

Interesting, logically you would think if both bulbs are the same and wired up same, same type of holder except one being a taller lamp, there should be no reason why the taller oen fails more often than the short one. of course vibrations, lose connections, slight arching at contact point or even arching on the switch itself may contribute to a shortened bulb life,
however, there are other factors that OP has not mentioned and these are;

1. Does the bulb fails when you just tried to switch on?
2. Or has it suddenly failed when it was already switched on for a while.
3. how often is the taller lamp switched on daily compared to the shorter lamp.

only then you could reach a slightly more explainable scenario, since most incandescent types of lamps fail on first switching on, and you have to be very unlucky if you just happen to hit the ON/OFF button from off to ON at a precise time when your mains voltage was looming at highest peak well above the nominal 230V ac, i.e. it may have shot up to say 245V !
In UK the mains can have an upper limit of 10% of nominal 230v hence it can often reach up to 253V and if you happen to strike your switch at the highest peak of the sine wave as well as slightly higher than nominal voltage it can pop your lamp. And sure you don't switch both lamps simultaneously, in many cases lamps failing on switch on also pops your MCBs.
I found 60watt candle shaped bulbs had worst life expectancy in my chandeliers, i have stopped using those and now use energy savers, they can last for years.

Thanks - it is number 1 always.
Number 3 - they are both used at the same time as it is my source of lighting in the living room.