One lamp bulb blows the other doesnt

[tom_cairns]

Tried them in what?

She tried them in the lamp, ie she replaced the bulbs and they both blew immediately

 

[JohnW2]

She tried them in the lamp, ie she replaced the bulbs and they both blew immediately

You mean in the tall lamp?

Did these new bulbs by any chance come from the same pile/batch/whatever that you have been using to replace the previous lamps which have died?

It may sound like a silly question, but it's just occurred me to ask whether you are certain that all of these 'blown' lamps/bulbs really have been 'blown'. Have you tried any of them in the other light before sending them to their graves?

Kind Regards, John

 

[tom_cairns]

You mean in the tall lamp?

Did these new bulbs by any chance come from the same pile/batch/whatever that you have been using to replace the previous lamps which have died?

It may sound like a silly question, but it's just occurred me to ask whether you are certain that all of these 'blown' lamps/bulbs really have been 'blown'. Have you tried any of them in the other light before sending them to their graves?

Kind Regards, John

Yes in the tall lamp. And yes, I took the bulb from the small lamp and tried it in the tall lamp to make sure it was the bulb - then I put the bulb back in the small lamp. They definitley wouldnt be from the same batch.

 

[333rocky333]

It still seems to me to be the lampholder, maybe worth seing if the supplier will swop the entire lamp, if it happens with the new one, then you will know its a house issue

 

[tom_cairns]

It still seems to me to be the lampholder, maybe worth seing if the supplier will swop the entire lamp, if it happens with the new one, then you will know its a house issue

They have already swapped it once!

 

[Mikefromlondon]

(op) Might be also worth checking if your mains supply voltage as you never know it may also be running well above or close to upper limit of 253V!

another factor why table lamp blows bulbs more than they would blow if they were on a ceiling holders, table lamps are connected to a 2.5mm ring mains effectively making them 5mm, whereas lights are usually on a radial of 1.5mm so any surge for high current demand by a cold filament bulb is limited by wiring resistance of lighting circuit on a 1.5mm. A cold filament bulb rated at 60watts can actually draw anything like 600watts for just a brief period, i.e. fraction of a second, and this is where it gets its shock that i call a thermal shock, which means heating so rapidly that it expands so quickly producing an actual physical movement suddenly and breaks, I have seen low wattage filaments under a microscope, they tend to vibrate all the time, and on switch on they can be subjected to higher forces both physically and thermally. So a low wiring resistance does not limit peak currents that can fuse a bulb just like a fuse blows.

A lot could be said by looking into a failed bulb, has the filament broken mid way or has it broken into several pieces, if broken into several pieces then it is a thermal shock as the jolt is so huge it virtually breaks it into more than one piece.

Same way one can say a lot about the way a fuse blows, if a fuse has gone black with a flash, and you cannot see any of the fuse link, that indicates a major dead short, on the other hand a fuse link is broken mid way, no flash or black marks, it simply blew due to overloading.

I have seen some thermal shocks so violent that a bulb just drops down to floor leaving its bayonet cap in the holder.

 

[333rocky333]

Oh i thought it was the two blown bulbs that were replaced, why did they originally also change the small light, are they a set of two

 

[tom_cairns]

Oh i thought it was the two blown bulbs that were replaced, why did they originally also change the small light, are they a set of two

Yes they came as a set and they replaced both lamps.

 

[tom_cairns]

(op) Might be also worth checking if your mains supply voltage as you never know it may also be running well above or close to upper limit of 253V!

How do I check that?

 

[JohnW2]

It still seems to me to be the lampholder, maybe worth seing if the supplier will swop the entire lamp ....

This is getting potentially very confusing. As you know, I'm certainly no fan of this new-fangled terminology, and this probably illustrates why!! ... when you say "the entire lamp", what exactly do you mean?

Kind Regards, John

 

[JohnW2]

And yes, I took the bulb from the small lamp and tried it in the tall lamp to make sure it was the bulb - then I put the bulb back in the small lamp.

I'm confused Did you trying taking one of the lamps/bulbs which appeared to have 'blown' in the taller light and try it in the smaller one?

Kind Regards, John

 

[333rocky333]

This changes things now, it seems the entire Tall fitting, plug, lampholder and lamp has been replaced due to the tall lamp bulbs failing, I assume,
as its part of a set, the Tall and the short entire fitting was replaced, the problems back with the (replaced) tall one
Hence i suspect the original post questioning the wall socket outlet

 

[333rocky333]

I'm confused Did you trying taking one of the lamps/bulbs which appeared to have 'blown' in the taller light and try it in the smaller one?

Kind Regards, John

Maybe it was typed wrong.
It seems the good bulb from the small lamp was tried in the tall lamp, then returned to the small lamp.
I assume that bulb worked in both.
this was after the wife blew 2 bulbs, No mention of how the bulbs blew, whether they breifly lit or what.
I am calling them bulbs to ease confusion

 

[Mikefromlondon]

As I said I do know where OP is coming from and makes no logical sense, I had a 3 bulb (candle style) chandelier and every month or so at least one of the bulbs would go mostly 9/10 times when first switched on, and it used to trip my 6 amp breaker as well. Like I said you have been unlucky as you may have hit the button when mains is on or near its peak wave, if it is near zero then not a problem for the bulb as it would take 10mS for mains to reach peak voltage and so the shock is limited, but if you had hit the button at or near zero, or when the mains wave was on its downwards incline from a peak 230v and had reached say 100V, then the shock is not so great, and in fact it would be diminishing as it would be reaching zero volts next and start in the opposite direction of the AC cycle, and take another 10mS to reach opposite peak. Its a hit and miss thing most of the time and again not every time a bulb switches at peak wave that it would blow instantly, again the bulb is designed to withstand certain abuse by its manufacturers, but often it just can't perform well enough.

(I do not have the figures with me, but I read an article once which said that a filament bulb running close to its limits cannot tolerate a small increase in voltage and also can give significantly less light when the nominal voltage drops by 10%, its light can drop by as much as 30%, I am going to try and dig that article out on google, but those figures are as examples and not actual.)

 

[JohnW2]

Maybe it was typed wrong. It seems the good bulb from the small lamp was tried in the tall lamp, then returned to the small lamp. I assume that bulb worked in both.

Yes, that's what I took him to mean - but what I was asking was whether he had tried one of the apparently-blown bulbs in the small light.

I am calling them bulbs to ease confusion

Thanks - I just wish that everyone would, always I have so often pointed out how much confusion can result from talking about "the lamp in the lamp", or asking for "a lamp for the lamp", but that's exactly what has been happening here!!

Kind Regards, John