Surprised to find large quantities of "2 for 1" 99p 18W/100W CF bulbs
by Philips, in Morrisons.
They claim 7000 hours.

I assume these are the same bulbs as were offered a few months back; if
so be aware that, based on personal experience, after a few months use
the bulbs start taking longer & longer to reach full brightness. I
fitted half a dozen at home when the offer last came round, the two
most used ones are taking much longer to brighten now. The worst cas
eis the bulb in the lounge, which has been switched on for maybe 10
hours per day during the winter months, but only switched on and off a
couple of times per day.

Ian Stirling wrote:
Surprised to find large quantities of "2 for 1" 99p 18W/100W CF bulbs
by Philips, in Morrisons.
They claim 7000 hours.

In my local Morrisons, the entire basket of them is Edison Screw fitting :-(

In ALDI, you can buy Osram's for a quid. I find these light up to
specified output quite quickly - the philips take a few tens of seconds
longer.

--
Adrian C

Ian Stirling wrote:
Surprised to find large quantities of "2 for 1" 99p 18W/100W CF bulbs
by Philips, in Morrisons.
They claim 7000 hours.

IME all "CF" lights, the sort that replace incandescent ones,
are rubbish. Why does the output drop off so quickly? Why do
they take time to brighten fully?

Adrian C wrote:
Ian Stirling wrote:
Surprised to find large quantities of "2 for 1" 99p 18W/100W CF bulbs
by Philips, in Morrisons.
They claim 7000 hours.

In my local Morrisons, the entire basket of them is Edison Screw fitting :-(

In my local one, there are two baskets (of equal sizes) with ES and
bayonet.
I have no idea if there are more in the back.

In ALDI, you can buy Osram's for a quid. I find these light up to
specified output quite quickly - the philips take a few tens of seconds
longer.


Over the first minute, just testing, the philips one seemed brightest
after about a minute.

Chris Bacon wrote:
Ian Stirling wrote:
Surprised to find large quantities of "2 for 1" 99p 18W/100W CF bulbs
by Philips, in Morrisons.
They claim 7000 hours.

IME all "CF" lights, the sort that replace incandescent ones,
are rubbish. Why does the output drop off so quickly? Why do
they take time to brighten fully?

The second one is partially due to reducing the amount of mercury in
them.

In article ,
Ian Stirling writes:
Chris Bacon wrote:
Ian Stirling wrote:
Surprised to find large quantities of "2 for 1" 99p 18W/100W CF bulbs
by Philips, in Morrisons.
They claim 7000 hours.

IME all "CF" lights, the sort that replace incandescent ones,
are rubbish. Why does the output drop off so quickly? Why do
they take time to brighten fully?

The second one is partially due to reducing the amount of mercury in
them.

Also, they are mostly designed to run with a tube wall temperature
of 100C, which is quite a bit different from the 20C when you
first switch them on. Traditional fluorescents are designed to run
with a tube wall temperature of 40C, which is not so different from
the initial switch-on temperature, so the initial brightness is not
so far off the final brightness.

--
Andrew Gabriel

Andrew Gabriel wrote:
In article ,
Ian Stirling writes:
Chris Bacon wrote:
Ian Stirling wrote:
Surprised to find large quantities of "2 for 1" 99p 18W/100W CF bulbs

IME all "CF" lights, the sort that replace incandescent ones,
are rubbish. Why does the output drop off so quickly? Why do
they take time to brighten fully?

The second one is partially due to reducing the amount of mercury in
them.

Also, they are mostly designed to run with a tube wall temperature
of 100C, which is quite a bit different from the 20C when you
first switch them on. Traditional fluorescents are designed to run
with a tube wall temperature of 40C, which is not so different from
the initial switch-on temperature, so the initial brightness is not
so far off the final brightness.

Even more so at low ambient temperatures.

wrote:
I assume these are the same bulbs as were offered a few months back; if
so be aware that, based on personal experience, after a few months use
the bulbs start taking longer & longer to reach full brightness. I
fitted half a dozen at home when the offer last came round, the two
most used ones are taking much longer to brighten now. The worst cas
eis the bulb in the lounge, which has been switched on for maybe 10
hours per day during the winter months, but only switched on and off a
couple of times per day.

How long is 'much longer? I may have a use for them at school if the
life of them is good enough.

Dave

Dave wrote:
wrote:
I assume these are the same bulbs as were offered a few months back; if
so be aware that, based on personal experience, after a few months use
the bulbs start taking longer & longer to reach full brightness. I
fitted half a dozen at home when the offer last came round, the two
most used ones are taking much longer to brighten now. The worst cas
eis the bulb in the lounge, which has been switched on for maybe 10
hours per day during the winter months, but only switched on and off a
couple of times per day.

How long is 'much longer? I may have a use for them at school if the
life of them is good enough.

The morrisons ones claim 6700 hours at 3 hours/day.

As with all CF devices, these are around 60lm/W, whereas the best linear
tubes are around 100lm/W.

Just as a side issue, can these low energy CF lamps be used in twin
concealed light fitting? The type that have the fitting screwed to the
ceilng and a glass dome covering the lamps.

Cheers

John.

John wrote:
Just as a side issue, can these low energy CF lamps be used in twin
concealed light fitting? The type that have the fitting screwed to the
ceilng and a glass dome covering the lamps.

If they physically fit, yes.
There may be an issue with them having slightly poorer life, if the
fitting is very insulating.
Of course, the fitting will run cooler than with ordinary bulbs, but the
CF lamps may be hotter than in free air.