Hi all,
I know there are various threads in here about the frequency with
which bulbs blow, but I've got a query with a slightly different
slant.

On our upstairs landing we have 2 lights, which are both on the same
switch circuit, the bulbs in one of the fittings blows regularly
(every 3-4 months), whereas the other fitting hasn't had a bulb blow
in years. We have changed the bulb in the 'good' fitting for a
flourescent bulb some time ago, we also swapped the bulb in the 'duff'
fitting at the same time - we've had normal and flourescent bulbs go
in this fitting. Last time a bulb went I checked the wiring for loose
connections and didn't find anything, I've just had another one go and
went and tightened up all the connections again but didn't see
anything out of the ordinary. The 'duff' fitting is wired straight
into the connector block of the ceiling rose in the 'good' fitting.
There is nothing in the location of the lights which could explain the
problems (i.e. neither are subject to draughts, knocks, excess heat
etc). Both lights are left on most of the night.

Anyone got any ideas?

M:

"Mal" wrote in message
om...
Hi all,
I know there are various threads in here about the frequency with
which bulbs blow, but I've got a query with a slightly different
slant.

On our upstairs landing we have 2 lights, which are both on the same
switch circuit, the bulbs in one of the fittings blows regularly
(every 3-4 months), whereas the other fitting hasn't had a bulb blow
in years. We have changed the bulb in the 'good' fitting for a
flourescent bulb some time ago, we also swapped the bulb in the 'duff'
fitting at the same time - we've had normal and flourescent bulbs go
in this fitting. Last time a bulb went I checked the wiring for loose
connections and didn't find anything, I've just had another one go and
went and tightened up all the connections again but didn't see
anything out of the ordinary. The 'duff' fitting is wired straight
into the connector block of the ceiling rose in the 'good' fitting.
There is nothing in the location of the lights which could explain the
problems (i.e. neither are subject to draughts, knocks, excess heat
etc). Both lights are left on most of the night.

Anyone got any ideas?

M:

You may not have noticed that the spring loaded connections which come
against the lamp terminals are loose or worn or burned. Do they have enough
tension in them to hold tightly against the lamp ? Are they marked with
carbon deposits on the tips ? When the lamp is inserted, does the lamp hold
tightly into the bayonet connector clasps ?

Try changing the lamp holder itself and see what happens.

"BigWallop" wrote in message ...
"Mal" wrote in message
om...
Hi all,
I know there are various threads in here about the frequency with
which bulbs blow, but I've got a query with a slightly different
slant.

On our upstairs landing we have 2 lights, which are both on the same
switch circuit, the bulbs in one of the fittings blows regularly
(every 3-4 months), whereas the other fitting hasn't had a bulb blow
in years. We have changed the bulb in the 'good' fitting for a
flourescent bulb some time ago, we also swapped the bulb in the 'duff'
fitting at the same time - we've had normal and flourescent bulbs go
in this fitting. Last time a bulb went I checked the wiring for loose
connections and didn't find anything, I've just had another one go and
went and tightened up all the connections again but didn't see
anything out of the ordinary. The 'duff' fitting is wired straight
into the connector block of the ceiling rose in the 'good' fitting.
There is nothing in the location of the lights which could explain the
problems (i.e. neither are subject to draughts, knocks, excess heat
etc). Both lights are left on most of the night.

Anyone got any ideas?

M:

You may not have noticed that the spring loaded connections which come
against the lamp terminals are loose or worn or burned. Do they have enough
tension in them to hold tightly against the lamp ? Are they marked with
carbon deposits on the tips ? When the lamp is inserted, does the lamp hold
tightly into the bayonet connector clasps ?

Try changing the lamp holder itself and see what happens.


Good point, I haven't examined them at all. I'll try it.

Thanks for the tip.

"Mal" wrote in message
om...
Hi all,
I know there are various threads in here about the frequency with
which bulbs blow, but I've got a query with a slightly different
slant.

On our upstairs landing we have 2 lights, which are both on the same
switch circuit, the bulbs in one of the fittings blows regularly
(every 3-4 months), whereas the other fitting hasn't had a bulb blow
in years. We have changed the bulb in the 'good' fitting for a
flourescent bulb some time ago, we also swapped the bulb in the 'duff'
fitting at the same time - we've had normal and flourescent bulbs go
in this fitting. Last time a bulb went I checked the wiring for loose
connections and didn't find anything, I've just had another one go and
went and tightened up all the connections again but didn't see
anything out of the ordinary. The 'duff' fitting is wired straight
into the connector block of the ceiling rose in the 'good' fitting.
There is nothing in the location of the lights which could explain the
problems (i.e. neither are subject to draughts, knocks, excess heat
etc). Both lights are left on most of the night.

Anyone got any ideas?

M:

Two reasons for premature bulb failu

a/ Overvoltage

b/ Vibration

Probably not a/ as other one on same circuit.

Andrew Mawson

In article ,
Mal wrote:
Anyone got any ideas?

One is getting more vibration than the other - for whatever reason.

--
*When blondes have more fun, do they know it?

Dave Plowman London SW 12
RIP Acorn

"Andrew Mawson" wrote in message ...

Two reasons for premature bulb failu
snip

Is it premature, in this case? The OP wrote:

the bulbs in one of the fittings blows regularly (every 3-4
months), whereas the other fitting hasn't had a bulb blow
in years.

Both lights are left on most of the night.

Taking "left on most of the night" to be (say) 10 hours per day, an ordinary
1000-hour GLS lamp is only going to last 100 days on average - which is
3-and-a-bit months. 8 hrs/day would give just over 4 months. These figures
will be very sensitive to voltage, which (unless you're in an all-electric
storage heater heated area) tends to rise at night when the supply network
is lightly loaded.

I think the real question is "why has the other bulb lasted so long"? (And
the answer is probably just "luck".)

--
Andy

"Andy Wade" wrote in message ...
"Andrew Mawson" wrote in message ...


SNIP

I think the real question is "why has the other bulb lasted so long"? (And
the answer is probably just "luck".)
The other fitting has had two different bulbs - we switched from
incandescent to flourescent a couple of years ago, both types of bulb
in that fitting have lasted - maybe we're _really_ lucky. Anyway the
lights are on for something like 10 hours a day although this annoys
me and I'm trying to get them turned off now the kids are getting
older (it's costing me money ;-).

Thanks for the reply.
M:

Dave Plowman wrote in message ...
In article ,
Mal wrote:
Anyone got any ideas?

One is getting more vibration than the other - for whatever reason.

I would have expected the one that lasts to be getting the most
vibration - it's in the centre of the house, near three doors and the
loft hatch, and at the top of the stairs, whereas the one that keeps
blowind is near the outside wall, and there's less traffic down that
end, I suppose there could be draughts round there - I'll look into
it.

Thanks again.