Victor Roberts wrote:
On 3 Dec 2006 05:24:07 -0800, wrote:

Electronic components are getting less expensive and sturdier, more
robust. Circuit designs are improved upon those that failed the test of
time.

This is correct, but it is not the relevant fact. What is relevant is
that the market is more cost driven and aggressive than in the past,
and many electronic goods that were once reliable have become much less
reliable, some to the point of disposable. This is primarily
competition driven. Electronic reliability depends on design margins,
and design margins depend on money. hence, not surprisingly, cheap
electronic goods are not known for reliability.

To replace a mag ballast with en electronic one and expect greater
reliability would be optimism over fact.

I don't think anyone has claimed that electronic ballasts
are more reliable than EM ballasts. After all, EM ballast
have only a few parts and perhaps 20 connections, while
electronic ballasts have perhaps 30 to 50 components and
perhaps 70 to 100 connections.

mag ballasts with 20 connections?? I've never seen anything like that
here, most have 2, some have 3. Sounds like you have some very exotic
ballasts over there.


EM ballasts have lives of well over 20 years, at least in
the US,

UK mag ballasts have mean lives of over a century. AFAIK it has never
dropped below this.

and it is not necessary for electronic ballasts to
have better reliability than EM ballasts in order for them
to be a good idea. If the life of an electronic ballast is
20 years, the room will probably be renovated before the
ballasts die.

I can't quite figure out why you believe that electronic
ballasts have serious reliability issues.

What I said was that their reliability does not compare to mag
ballasts. This is true. Thus reliability is not a reason to replace the
fitting.


It sounds like
you are stuck in 1980, a few years after the introduction of
electronic ballasts.

lets keep it sensible now

I assume you own a TV set, some sort
of music system, perhaps a DVD player, own a car with an
electronic control system, travel in airplanes that use
electronic control systems, and, yes, that computer that you
are using to post your messages. I have not seem any
mechanical computers that have newsgroup readers, so I
assume you are using an electronic computer :-)

I'm not sure why you're having difficulty accepting that one is more
reliable than the other. They just dont compare when it comes to
reliabilty. None of the above has anything to do with it.


In 2005 there were 61,269,000 electronic fluorescent lamp
ballasts sold in the US. See Current Industrial Reports -
Fluorescent Lamp Ballasts: 2001, available at
http://www.census.gov/cir/www/335/mq335c.html.

With this many ballast sold, we would have a lot of very
angry customers if the failure rate was not very low.

We have precisely that situation with a whole range of consumer goods
here. Many cheap end goods have appalling lifetimes, eg power tools
that die after 10 hrs use. Sellers count on replacing a percentage,
users buy them mostly in ignorance, and less often when they know but
are in no position to take the tool with them. There are large
quantities of angry customers, but far more that are willing to buy on
price alone, so business continues.

Its probably best policy to establish the facts before being
condescending.


NT

In article .com,
wrote:
Don Klipstein wrote:

Although I agree with these presented facts, I do not find majority
extent (slightly short of 100% even if hardly) of negation of some
advantages of electronic ballasts to be any argument at all against
arguments on basis of unrelated issues such as energy efficiency (reduce
power consumption anywhere from roughly 7 watts to roughly 25 watts per
pair of 4-footers, depending on who you listen to and also depending on
what you do! Replace a pair of F40T12's and a non-electronic ballast for
these with a pair of F32T8's and an electronic ballast for those and power
consumption has a good chance of being decreased by roughly 24-25 watts -

Replace a 40w tube with a 36w T8 and the power use also falls, though
not as much as that, due to mag ballast losses.

However, that is not the real world comparison. The real world energy
comparison also involves:
- energy used in transport to go get a new fitting

To toss some numbers, suppose 100 units transported 25 miles each way in
a truck that gets 8 MPG. (Really long trips would more likely involve a
whole truckload of units.)
One unit's share of the truck mileage is .6 mile, and at 8 MPG that's
..075 gallon of gasoline. If I calculated right, that's roughly 2.6
kilowatt hours. A 25 watt power consumption only requires about 104
operating hours to make that up.

- energy used in manufacture of new fittings
- energy used in parts/materials of new fitting

Somehow I suspect the factory's price for decent ones in quantities of
100,000's has to be less than the retail price of a cheap garbage grade
dual-4-foot shoplight with a garbage grade magnetic ballast - and I have
heard of about $10 for those.
So, I don't think I'm badly out of the ballpark to pull out of a hat $8
for a 2-lamp 4-foot unit, FOB the factory's loading dock in truckload
quantities. Just for the sake of argument, suppose 100% of that cost was
for energy to obtain materials and to manufacture the unit - starting from
dirt/rocks/air/water that is. Suppose 8 cents per kilowatt hour. That's
1,000 KWH, which a 25 watt savings will make up in 40,000 operating hours,
which most 4-foot fixtures will accumulate in a decade or two.

Somehow I think that figure is high by at least an order of magnitude.

- energy used in disposal of old fitting

Weighing .005-.01 ton? How much diesel fuel to truck round-trip 20 tons
of trash to a landfill 100 miles away - 40 gallons or less? .01-.02
gallon per unit - requiring maybe 15-30 operating hours for a 25 watt
power consumption decrease to make up?

- energy used in manufacturing, supplying and applying a coat of paint
to the ceiling when end user notices the new fitting is not identically
sized to the old, and the resulting paint appearance is bad.

Usually not the case - sizes of fluoresceint lighting units are
well-standardized. This is especially true for the ones to fit into the
drop ceilings that most offices have nowadays, where a fixture replacement
will not require repainting - especially not of acoustic tile!

Meanwhile, the share ceiling space associated with one luminaire
requires how much paint? Something like half a dollar to a dollar's
worth? Even if 100% of the cost of the paint is from energy consumption,
that would be in the ballpark of half a dollar to a dollar's worth of
electricity. At 8 cents per KWH, a power reduction of 25 watts accounts
for half a dollar to a dollar in 250-500 operating hours.
As for applying the paint in the unlikely event that is required - burn
50 calories or 12 cents worth of potato chips?

If you do a real world energy comparison, it is more than hard to
justify replacing the fitting on energy saving grounds.

Don Klipstein )

On 3 Dec 2006 04:51:54 -0800, wrote:

[snip]

If you do a real world energy comparison, it is more than hard to
justify replacing the fitting on energy saving grounds.

No product can cost less than the cost of the energy used to
produce that product and all it component parts, including
all the energy needed to extract and transport the raw
materials. This is basic economics.

The value of the energy saved is far greater than the cost
of the new lamps, ballasts and luminaires. (If it were not,
people would never make the switch.) Even if the user of
the luminaire pays a higher rate for energy than the
industrial users who built and transported the device, the
cost savings would tend to rule out your assertion.

--
Vic Roberts
http://www.RobertsResearchInc.com
To reply via e-mail:
replace xxx with vdr in the Reply to: address
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This information is provided for educational purposes only.
It may not be used in any publication or posted on any Web
site without written permission.

On 3 Dec 2006 10:30:22 -0800, wrote:

Victor Roberts wrote:
On 3 Dec 2006 05:24:07 -0800, wrote:

Electronic components are getting less expensive and sturdier, more
robust. Circuit designs are improved upon those that failed the test of
time.

This is correct, but it is not the relevant fact. What is relevant is
that the market is more cost driven and aggressive than in the past,
and many electronic goods that were once reliable have become much less
reliable, some to the point of disposable. This is primarily
competition driven. Electronic reliability depends on design margins,
and design margins depend on money. hence, not surprisingly, cheap
electronic goods are not known for reliability.

To replace a mag ballast with en electronic one and expect greater
reliability would be optimism over fact.

I don't think anyone has claimed that electronic ballasts
are more reliable than EM ballasts. After all, EM ballast
have only a few parts and perhaps 20 connections, while
electronic ballasts have perhaps 30 to 50 components and
perhaps 70 to 100 connections.

mag ballasts with 20 connections?? I've never seen anything like that
here, most have 2, some have 3. Sounds like you have some very exotic
ballasts over there.

Internal connections, not external. That is one measure of
mean time to failure.

EM ballasts have lives of well over 20 years, at least in
the US,

UK mag ballasts have mean lives of over a century. AFAIK it has never
dropped below this.

How do you know this since fluorescent lamps have not been
around for 100 years? Even if this is correct, and I guess
it might be for a simple choke ballast, how many remain in
ceilings for 100 years?

When Philips first showed the QL at Hannover in 1992 or
perhaps 1993 they gave an estimated life of 60,000 hours
(at that time) and said it was the "life of the building"
since the space would be renovated before the lamp had
operated for 60K hours. I'm not sure I agree with 60K hours
life for a building space, but it is certainly not 100
years.

and it is not necessary for electronic ballasts to
have better reliability than EM ballasts in order for them
to be a good idea. If the life of an electronic ballast is
20 years, the room will probably be renovated before the
ballasts die.

I can't quite figure out why you believe that electronic
ballasts have serious reliability issues.

What I said was that their reliability does not compare to mag
ballasts. This is true. Thus reliability is not a reason to replace the
fitting.


It sounds like
you are stuck in 1980, a few years after the introduction of
electronic ballasts.

lets keep it sensible now

I assume you own a TV set, some sort
of music system, perhaps a DVD player, own a car with an
electronic control system, travel in airplanes that use
electronic control systems, and, yes, that computer that you
are using to post your messages. I have not seem any
mechanical computers that have newsgroup readers, so I
assume you are using an electronic computer :-)

I'm not sure why you're having difficulty accepting that one is more
reliable than the other. They just dont compare when it comes to
reliabilty. None of the above has anything to do with it.

I agreed with this in my opening remarks.

In 2005 there were 61,269,000 electronic fluorescent lamp
ballasts sold in the US. See Current Industrial Reports -
Fluorescent Lamp Ballasts: 2001, available at
http://www.census.gov/cir/www/335/mq335c.html.

With this many ballast sold, we would have a lot of very
angry customers if the failure rate was not very low.

We have precisely that situation with a whole range of consumer goods
here. Many cheap end goods have appalling lifetimes, eg power tools
that die after 10 hrs use. Sellers count on replacing a percentage,
users buy them mostly in ignorance, and less often when they know but
are in no position to take the tool with them. There are large
quantities of angry customers, but far more that are willing to buy on
price alone, so business continues.

So, are you comparing the reliability of electronic ballasts
to cheap electric tools that fail in 10 hours? What is your
point in this comparison?

Its probably best policy to establish the facts before being
condescending.

How true.

--
Vic Roberts
http://www.RobertsResearchInc.com
To reply via e-mail:
replace xxx with vdr in the Reply to: address
or use e-mail address listed at the Web site.

This information is provided for educational purposes only.
It may not be used in any publication or posted on any Web
site without written permission.

Victor Roberts wrote:
On 3 Dec 2006 04:51:54 -0800, wrote:

If you do a real world energy comparison, it is more than hard to
justify replacing the fitting on energy saving grounds.

No product can cost less than the cost of the energy used to
produce that product and all it component parts, including
all the energy needed to extract and transport the raw
materials. This is basic economics.

The value of the energy saved is far greater than the cost
of the new lamps, ballasts and luminaires. (If it were not,
people would never make the switch.) Even if the user of
the luminaire pays a higher rate for energy than the
industrial users who built and transported the device, the
cost savings would tend to rule out your assertion.

Its not hard to see other reasons why old fittings are replaced with
new.


NT

Victor Roberts wrote:
On 3 Dec 2006 10:30:22 -0800, wrote:
Victor Roberts wrote:
On 3 Dec 2006 05:24:07 -0800, wrote:

I don't think anyone has claimed that electronic ballasts
are more reliable than EM ballasts. After all, EM ballast
have only a few parts and perhaps 20 connections, while
electronic ballasts have perhaps 30 to 50 components and
perhaps 70 to 100 connections.

mag ballasts with 20 connections?? I've never seen anything like that
here, most have 2, some have 3. Sounds like you have some very exotic
ballasts over there.

Internal connections, not external. That is one measure of
mean time to failure.

mag ballasts normally have 2 internal connections, one at each end of
the winding.


EM ballasts have lives of well over 20 years, at least in
the US,

UK mag ballasts have mean lives of over a century. AFAIK it has never
dropped below this.

How do you know this since fluorescent lamps have not been
around for 100 years?

this is basic stuff. If for example 50% had died after 50 years, we'd
know mean life was apx 50 years. If 10% died after 50 years we'd know
mean life was nearer 500, etc. Lots of items are life rated at beyond
the time theyve existed on this basis, standard industry practice.


Even if this is correct, and I guess
it might be for a simple choke ballast, how many remain in
ceilings for 100 years?

irrelevant. Relevant is the failure rate in real life service times,
which depends on mean life, or MTTF.


In 2005 there were 61,269,000 electronic fluorescent lamp
ballasts sold in the US. See Current Industrial Reports -
Fluorescent Lamp Ballasts: 2001, available at
http://www.census.gov/cir/www/335/mq335c.html.
With this many ballast sold, we would have a lot of very
angry customers if the failure rate was not very low.

We have precisely that situation with a whole range of consumer goods
here. Many cheap end goods have appalling lifetimes, eg power tools
that die after 10 hrs use. Sellers count on replacing a percentage,
users buy them mostly in ignorance, and less often when they know but
are in no position to take the tool with them. There are large
quantities of angry customers, but far more that are willing to buy on
price alone, so business continues.

So, are you comparing the reliability of electronic ballasts
to cheap electric tools that fail in 10 hours? What is your
point in this comparison?

are you being serious here? The point is that lots of uk consumer goods
are not reliable today. The point is that thus replacing an old fitting
with a new one does not improve expected reliability. And that
reliability is thus not a reason to replace the fitting.


NT

On 4 Dec 2006 03:51:34 -0800, wrote:

Victor Roberts wrote:
On 3 Dec 2006 10:30:22 -0800, wrote:
Victor Roberts wrote:
On 3 Dec 2006 05:24:07 -0800, wrote:

I don't think anyone has claimed that electronic ballasts
are more reliable than EM ballasts. After all, EM ballast
have only a few parts and perhaps 20 connections, while
electronic ballasts have perhaps 30 to 50 components and
perhaps 70 to 100 connections.

mag ballasts with 20 connections?? I've never seen anything like that
here, most have 2, some have 3. Sounds like you have some very exotic
ballasts over there.

Internal connections, not external. That is one measure of
mean time to failure.

mag ballasts normally have 2 internal connections, one at each end of
the winding.

This is only true for simple reactor ballasts. 2-lamp EM
fluorescent lamp ballasts used in the US have multiple
internal windings and two capacitors.

EM ballasts have lives of well over 20 years, at least in
the US,

UK mag ballasts have mean lives of over a century. AFAIK it has never
dropped below this.

How do you know this since fluorescent lamps have not been
around for 100 years?

this is basic stuff. If for example 50% had died after 50 years, we'd
know mean life was apx 50 years. If 10% died after 50 years we'd know
mean life was nearer 500, etc. Lots of items are life rated at beyond
the time theyve existed on this basis, standard industry practice.

You must know this is only true for a linear mortality
curve. Please take a look at a typical mortality curve and
you will see that it is far from linear. The failure rate
for times much earlier than mean life cannot predict the
mean life point.

--
Vic Roberts
http://www.RobertsResearchInc.com
To reply via e-mail:
replace xxx with vdr in the Reply to: address
or use e-mail address listed at the Web site.

This information is provided for educational purposes only.
It may not be used in any publication or posted on any Web
site without written permission.

Victor Roberts wrote:
On 4 Dec 2006 03:51:34 -0800, wrote:
Victor Roberts wrote:
On 3 Dec 2006 10:30:22 -0800, wrote:
Victor Roberts wrote:
On 3 Dec 2006 05:24:07 -0800, wrote:

I don't think anyone has claimed that electronic ballasts
are more reliable than EM ballasts. After all, EM ballast
have only a few parts and perhaps 20 connections, while
electronic ballasts have perhaps 30 to 50 components and
perhaps 70 to 100 connections.

mag ballasts with 20 connections?? I've never seen anything like that
here, most have 2, some have 3. Sounds like you have some very exotic
ballasts over there.

Internal connections, not external. That is one measure of
mean time to failure.

mag ballasts normally have 2 internal connections, one at each end of
the winding.

This is only true for simple reactor ballasts. 2-lamp EM
fluorescent lamp ballasts used in the US have multiple
internal windings and two capacitors.

In UK, which is the area we're talking about, mag ballasts are always 2
wires, theyre just a series choke. 2 lamp shop fiting ballasts are also
just a choke. Even 8' tubes use a series choke ballast.


EM ballasts have lives of well over 20 years, at least in
the US,

UK mag ballasts have mean lives of over a century. AFAIK it has never
dropped below this.

How do you know this since fluorescent lamps have not been
around for 100 years?

this is basic stuff. If for example 50% had died after 50 years, we'd
know mean life was apx 50 years. If 10% died after 50 years we'd know
mean life was nearer 500, etc. Lots of items are life rated at beyond
the time theyve existed on this basis, standard industry practice.

You must know this is only true for a linear mortality
curve. Please take a look at a typical mortality curve and
you will see that it is far from linear. The failure rate
for times much earlier than mean life cannot predict the
mean life point.

yes of course, to all 3 points. I was simply pointing out one does not
need to run fl lighting for 100yrs to see mttf for mag ballasts is over
100 years. Failures are few with these things.


NT

In article ,
Victor Roberts writes:
On 4 Dec 2006 03:51:34 -0800, wrote:
mag ballasts normally have 2 internal connections, one at each end of
the winding.

This is only true for simple reactor ballasts.

That's what they mostly are on 230V supplies.

2-lamp EM
fluorescent lamp ballasts used in the US have multiple
internal windings and two capacitors.

2-lamp EM fluorescent lamp ballasts commonly used in
offices here are just one ballast and two tubes in series,
so that drops to just a single internal connection per tube ;-)
(It also makes the ballast more than twice as efficient
as a pair of separate ballasts driving separate tubes.)

This is partly what I was getting at in an earlier post where
I said the economics just seem quite different between US/120V
and EU/230V control gear systems.

You must know this is only true for a linear mortality
curve. Please take a look at a typical mortality curve and
you will see that it is far from linear. The failure rate
for times much earlier than mean life cannot predict the
mean life point.

I've never come across any simple series ballasts failing in
UK fluorescent fittings (except in one case where water came
through the ceiling). At this point, I think we can say their
life is longer than they've been around.

We have also had some more complex EM control gear designs,
but I've not come across enough to comment on their
reliability as they're relatively rare.

--
Andrew Gabriel

Andrew Gabriel wrote:

I've never come across any simple series ballasts failing in
UK fluorescent fittings (except in one case where water came
through the ceiling). At this point, I think we can say their
life is longer than they've been around.

Yes, and I think on reflection a century mttf is probably too
pessimistic.

When they do fail, which is very uncommon, I wonder how many of those
failures are secondary issues, eg ballast failure due to wiring
shorting to case, which can place them directly across 240v ac. Or a
glowstarter welded shorting, which puts most of 240 across the ballast.


NT

Andrew Gabriel wrote:

Not in a 15 year old fitting. You'd need a 45 year old fitting
which would also have B22d (bayonet cap) connections on the tube
ends ;-)

I recently noticed that there are a few of these still in use where I
work; two of them right outside my office. Most of them have had the
ofiginal lampholders replaced, but it least one, in the sparks'
workshop, still has the original ones, with bipin adaptors. In a
little-used storeroom there are two that still have the original covers
over the lampholders and clips. I'd like to acquire one of these when
they are taken down. The whole building is being gutted and
refurbished over the next few years, so they won't be there much
longer. There was one leaning against the wall by the boiler house
door recently, together with the box that its replacement came in. I
looked at it, but the ballast was burned out. I had a word with the
sparks, and he let me have the two large four-pin starters out of it.

In article . com,
writes:

Andrew Gabriel wrote:

Not in a 15 year old fitting. You'd need a 45 year old fitting
which would also have B22d (bayonet cap) connections on the tube
ends ;-)

I recently noticed that there are a few of these still in use where I
work; two of them right outside my office. Most of them have had the
ofiginal lampholders replaced, but it least one, in the sparks'
workshop, still has the original ones, with bipin adaptors. In a
little-used storeroom there are two that still have the original covers
over the lampholders and clips. I'd like to acquire one of these when
they are taken down. The whole building is being gutted and
refurbished over the next few years, so they won't be there much
longer. There was one leaning against the wall by the boiler house
door recently, together with the box that its replacement came in. I
looked at it, but the ballast was burned out. I had a word with the
sparks, and he let me have the two large four-pin starters out of it.

Unless it's a very old thermal four-pin starter, you'll find
that inside is just a regular glow starter across the locking
pins, and the small pins are simply shorted together. It's
most unlikely an original thermal starter would still be
working unless it was in some situation where it wasn't used
for 50 years.

I did notice "The Shop on the Bridge" in Reading had some
bayonet cap fluorescent tubes on sale when I was last in there
about 2 years ago. Knowing them, they might well be 1950's
stock;-) Bayonet cap to bi-pin adaptors were very common 40
years ago when the bayonet cap tubes were phased out, but it's
probably easier to buy a flying bi-pin socket nowadays and swap
out the bayonet cap lampholder, if you want to run those lamps.

Of course, you could fit a modern ballast if you just want the
fitting for 1950's styling.

--
Andrew Gabriel

Andrew Gabriel wrote:
In article . com,
writes:
Andrew Gabriel wrote:

Not in a 15 year old fitting. You'd need a 45 year old fitting
which would also have B22d (bayonet cap) connections on the tube
ends ;-)

I recently noticed that there are a few of these still in use where I
work; two of them right outside my office. Most of them have had the
ofiginal lampholders replaced, but it least one, in the sparks'
workshop, still has the original ones, with bipin adaptors. In a
little-used storeroom there are two that still have the original covers
over the lampholders and clips. I'd like to acquire one of these when
they are taken down. The whole building is being gutted and
refurbished over the next few years, so they won't be there much
longer. There was one leaning against the wall by the boiler house
door recently, together with the box that its replacement came in. I
looked at it, but the ballast was burned out. I had a word with the
sparks, and he let me have the two large four-pin starters out of it.

Unless it's a very old thermal four-pin starter, you'll find
that inside is just a regular glow starter across the locking
pins, and the small pins are simply shorted together. It's
most unlikely an original thermal starter would still be
working unless it was in some situation where it wasn't used
for 50 years.

I did notice "The Shop on the Bridge" in Reading had some
bayonet cap fluorescent tubes on sale when I was last in there
about 2 years ago. Knowing them, they might well be 1950's
stock;-) Bayonet cap to bi-pin adaptors were very common 40
years ago when the bayonet cap tubes were phased out, but it's
probably easier to buy a flying bi-pin socket nowadays and swap
out the bayonet cap lampholder, if you want to run those lamps.

Of course, you could fit a modern ballast if you just want the
fitting for 1950's styling.

I was using a thermal starter or 2 in the 80s, still working fine. The
way they light tells you which they are, thermal or glow.

The ballasts are the same, so getting a dead ballast fitting doesnt
stop it being fixed & used.

There is one gotcha with very old fl fittings, some have capacitors
that contain pcbs, polysomething biphenols or someting vaguely like
that. Supposed to be quite nasty stuff and prone to leaking, so treat
old pfc caps with a bit of caution, especially if oily/greasy.


NT

Andrew Gabriel wrote:

I did notice "The Shop on the Bridge" in Reading had some
bayonet cap fluorescent tubes on sale when I was last in there
about 2 years ago. Knowing them, they might well be 1950's
stock;-) Bayonet cap to bi-pin adaptors were very common 40
years ago when the bayonet cap tubes were phased out, but it's
probably easier to buy a flying bi-pin socket nowadays and swap
out the bayonet cap lampholder, if you want to run those lamps.

Where is this shop; I'd like to get hold of a bayonet tube, or two?

Of course, you could fit a modern ballast if you just want the
fitting for 1950's styling.

I'd like to get gold of one of the ones which still have the bayonet
holders if possible, or failing that, one of the converted ones, and
convert it back. I really want one with the original control gear. I
did find one bipin adapter on the floor in one of the lift machine
rooms, but I couldn't find another one. It has a small 'tab' on one
side, which I assume is intended to make contact with the metlic
stripe, on tubes that had it, MCFA I think was the designation. The
lifts were replaced about 18 months ago; the original ones lasted about
50 years; I would be surprised if the new ones manage 20, Two of the
old ones had beed modernised some years ago, but the third still had
its dc drive and motor-generator set until it was replaced. The
machine room has modern fluorescent fittings, probably installed at the
time the lifts were replaced.

In article . com,
writes:
Andrew Gabriel wrote:
I did notice "The Shop on the Bridge" in Reading had some
bayonet cap fluorescent tubes on sale when I was last in there
about 2 years ago. Knowing them, they might well be 1950's
stock;-) Bayonet cap to bi-pin adaptors were very common 40
years ago when the bayonet cap tubes were phased out, but it's
probably easier to buy a flying bi-pin socket nowadays and swap
out the bayonet cap lampholder, if you want to run those lamps.

Where is this shop; I'd like to get hold of a bayonet tube, or two?

http://www.streetmap.co.uk/newmap.srf?x=468588&y=174158

I suggest you phone before travelling, to make sure they
have one in the right size (supposing they still have any).

Of course, you could fit a modern ballast if you just want the
fitting for 1950's styling.

I'd like to get gold of one of the ones which still have the bayonet
holders if possible, or failing that, one of the converted ones, and
convert it back. I really want one with the original control gear. I
did find one bipin adapter on the floor in one of the lift machine
rooms, but I couldn't find another one. It has a small 'tab' on one

I can see the tab in a picture. The Thorn part number is GB1515.

side, which I assume is intended to make contact with the metlic
stripe, on tubes that had it, MCFA I think was the designation. The

Not sure, as you won't need MCFA tubes in these metal fittings with
switchstart control gear. They were for Quickstart and Rapid start
control gear where the tube was not near earthed metalwork. I don't
think these starterless control gear types appeared until after BC
fittings had gone, but I might be wrong.

lifts were replaced about 18 months ago; the original ones lasted about
50 years; I would be surprised if the new ones manage 20, Two of the
old ones had beed modernised some years ago, but the third still had
its dc drive and motor-generator set until it was replaced. The
machine room has modern fluorescent fittings, probably installed at the
time the lifts were replaced.

By the way, the history of the bayonet cap fluorescent tubes is
interesting. The first fluorescent tube installation in the UK
was in one of the London Underground stations around 1937 IIRC.
During WWII, there was a move to switch over to more fluorescent
lighting, but the lampholders which came from the US were no
longer available (I don't know if they were bi-pin at that point).
Ever resourceful, they decided that if they were swapping out
filament lamps, they could reuse the lampholders if the fluorescents
used the same type, so fluorescents switched over to BC lampholders.
The 4' tube (which was the original size used in the US at that point)
was abandoned in the UK during WWII, and 5', 6' and 8' tubes produced
because installations of these used fewer raw materials. The 4' tube
didn't reappear in the UK for some time after the war (I guess mid
1950's, but I don't know for sure) and had bi-pin lampholders.
The other tube sizes then changed to bi-pin too.

--
Andrew Gabriel