Fluorescent Lights
 

Hi All

Ws doing a few jobs in an office today and the customer asked me to change a
few fluorescent tubes. Seemed simple enough. The fixtures had three tubes
in each. In one office they told me two tubes had gone, they replaced them
and they blew again.

At their request I changed two tubes and all three starters (which they
supplied). They old starters seemed to be brittle as though they had been
exposed to excess heat.

The tubes appeared to be wired in series? Is that right? When I switched
on, the unchanged tube still worked fine, but the other two flicked on and
off alternatively. You could see that one end of the tubes was getting hot,
so I switched off & removed the two tubes I had changed.

In the office next door they had a three tube fitting with only two tubes
installed. They had apparently removed the third tube because it flickered.
One of the two remaining tubes had started to flicker. I changed two tubes
and one starter and it works a treat.

Any idea what could be wrong? I have little experience of fluorescent
lighting. I suggested they get a sparky to look at the first fitting.


--
Dave
The Medway Handyman
www.medwayhandyman.co.uk
01634 717930
07850 597257

Fluorescent Lights
 

In article ,
"The Medway Handyman" writes:
Hi All

Ws doing a few jobs in an office today and the customer asked me to change a
few fluorescent tubes. Seemed simple enough. The fixtures had three tubes
in each. In one office they told me two tubes had gone, they replaced them
and they blew again.

At their request I changed two tubes and all three starters (which they
supplied). They old starters seemed to be brittle as though they had been
exposed to excess heat.

Maybe, but also the UV from the tubes can cause this.

The tubes appeared to be wired in series? Is that right? When I switched

It is common to wire two 2' 18W tubes in series, but you need
starters designed for series operation (actually, they are same
as the starters used for 120V mains). In your 3-lamp fittings,
you'll probably find one series pair and one standalone, and the
series pair will require different starters from the standalone.

on, the unchanged tube still worked fine, but the other two flicked on and
off alternatively. You could see that one end of the tubes was getting hot,

How could you see that?

so I switched off & removed the two tubes I had changed.

In the office next door they had a three tube fitting with only two tubes
installed. They had apparently removed the third tube because it flickered.
One of the two remaining tubes had started to flicker. I changed two tubes
and one starter and it works a treat.

Any idea what could be wrong? I have little experience of fluorescent
lighting. I suggested they get a sparky to look at the first fitting.

Wrong starters possibly. Do the fittings have loose end-caps
which could have been cross routed to the wrong tube-ends?

--
Andrew Gabriel

Fluorescent Lights
 

The Medway Handyman wrote:

Hi All

Ws doing a few jobs in an office today and the customer asked me to change a
few fluorescent tubes. Seemed simple enough. The fixtures had three tubes
in each. In one office they told me two tubes had gone, they replaced them
and they blew again.

At their request I changed two tubes and all three starters (which they
supplied). They old starters seemed to be brittle as though they had been
exposed to excess heat.

The tubes appeared to be wired in series? Is that right? When I switched
on, the unchanged tube still worked fine, but the other two flicked on and
off alternatively. You could see that one end of the tubes was getting hot,
so I switched off & removed the two tubes I had changed.

In the office next door they had a three tube fitting with only two tubes
installed. They had apparently removed the third tube because it flickered.
One of the two remaining tubes had started to flicker. I changed two tubes
and one starter and it works a treat.

Any idea what could be wrong? I have little experience of fluorescent
lighting. I suggested they get a sparky to look at the first fitting.

I think your questions been answered now, most likely a starter
problem. The usual drill is to replace just the starters first, and if
it still wont run then replace the tubes. Tubes in series means you
need series starters, using ordinary ones may not work.

But you wont find 3 tubes in series, as already said.

Quite likely some of the tubes you took out are fine.


NT

Fluorescent Lights
 

Andrew Gabriel wrote:

It is common to wire two 2' 18W tubes in series, but you need
starters designed for series operation (actually, they are same
as the starters used for 120V mains). In your 3-lamp fittings,
you'll probably find one series pair and one standalone, and the
series pair will require different starters from the standalone.

These were 4' tubes, not sure of the wattage.

on, the unchanged tube still worked fine, but the other two flicked
on and off alternatively. You could see that one end of the tubes
was getting hot,

How could you see that?

One end looked red and felt hot.


Wrong starters possibly. Do the fittings have loose end-caps
which could have been cross routed to the wrong tube-ends?

No, the end caps were firmly fixed in place and all the wires tied in.


--
Dave
The Medway Handyman
www.medwayhandyman.co.uk
01634 717930
07850 597257

Fluorescent Lights
 

In article ,
"The Medway Handyman" writes:
Andrew Gabriel wrote:

It is common to wire two 2' 18W tubes in series, but you need
starters designed for series operation (actually, they are same
as the starters used for 120V mains). In your 3-lamp fittings,
you'll probably find one series pair and one standalone, and the
series pair will require different starters from the standalone.

These were 4' tubes, not sure of the wattage.

You can't run 4' tubes in series on a simple series ballast -- there's
not enough headroom between the sum of the tube voltages and mains voltage.
Some electronic ballasts do run multiple tubes in series, but they don't
use starters.

on, the unchanged tube still worked fine, but the other two flicked
on and off alternatively. You could see that one end of the tubes
was getting hot,

How could you see that?

One end looked red and felt hot.

Both ends should get exactly same heating. If one end glows
red and the other end white, then the red end of the tube has
run out of emission coating on the filament (usually ends up
coated around the tube end as black marks), and tube is dead.

I can't imagine what type of setup you are looking at, sorry.

--
Andrew Gabriel

Fluorescent Lights
 

The Medway Handyman wrote:
Andrew Gabriel wrote:

These were 4' tubes, not sure of the wattage.

on, the unchanged tube still worked fine, but the other two flicked
on and off alternatively. You could see that one end of the tubes
was getting hot,

How could you see that?

One end looked red and felt hot.


Wrong starters possibly. Do the fittings have loose end-caps
which could have been cross routed to the wrong tube-ends?

No, the end caps were firmly fixed in place and all the wires tied in.

The 2 end filaments are in in series during start on glow start
fittings. They will always get the same power, and thus glow the same
colour. (Thermionic emission does not affect colour) If the tube ends
are glowing different colours, something's wrong, maybe a wiring fault.

With 4' tubes check youre not using:
a 4-20w statrer
a 100-125w starter
a series starter


NT

Fluorescent Lights
 

wrote:

With 4' tubes check youre not using:
a 4-20w statrer
a 100-125w starter
a series starter

I think the starters had 4 - 80 printed on them. I'll call the customer &
confirm that. I think they bought a box of starters from their office
supply company, so they could well be the wrong type.

Thanks for your help.


--
Dave
The Medway Handyman
www.medwayhandyman.co.uk
01634 717930
07850 597257

Fluorescent Lights
 

The Medway Handyman wrote:
wrote:

With 4' tubes check youre not using:
a 4-20w statrer
a 100-125w starter
a series starter

I think the starters had 4 - 80 printed on them. I'll call the customer &
confirm that. I think they bought a box of starters from their office
supply company, so they could well be the wrong type.

Thanks for your help.

they sound ok... if a new tube and new starter dont fix it then either
the new bits are faulty or the fitting has gone wrong somewhere. I get
the feeling you wont be offering fitting repairs.


NT

Fluorescent Lights
 

wrote:
they sound ok... if a new tube and new starter dont fix it then either
the new bits are faulty or the fitting has gone wrong somewhere. I get
the feeling you wont be offering fitting repairs.

Dead right! I only changed them as a favour!

I'd like to learn a bit more about fluorescent lights. Is there a web site
with any info that would help?


--
Dave
The Medway Handyman
www.medwayhandyman.co.uk
01634 717930
07850 597257

Fluorescent Lights
 

The message
from "The Medway Handyman" contains
these words:

I'd like to learn a bit more about fluorescent lights. Is there a web site
with any info that would help?

I'm sure someone will tell me that Wikipedia is crap[1] - but this has
quite a lot of info
http://en.wikipedia.org/wiki/Fluorescent_lamp

[1] And if they do they can go edit it.

--
Skipweasel
Pay no attention to that man behind the curtain.

Fluorescent Lights
 

The Medway Handyman wrote:
wrote:
they sound ok... if a new tube and new starter dont fix it then either
the new bits are faulty or the fitting has gone wrong somewhere. I get
the feeling you wont be offering fitting repairs.

Dead right! I only changed them as a favour!

classic mistake :) When they ask that its because they darent ask
anyone to take it on as a real job.

I'd like to learn a bit more about fluorescent lights. Is there a web site
with any info that would help?


NT

Fluorescent Lights
 

Guy King wrote:
The message
from "The Medway Handyman" contains
these words:

I'd like to learn a bit more about fluorescent lights. Is there a web site
with any info that would help?

I'm sure someone will tell me that Wikipedia is crap[1] - but this has
quite a lot of info
http://en.wikipedia.org/wiki/Fluorescent_lamp

[1] And if they do they can go edit it.

actually there are problems with that article. The info Dave needs isnt
there, and a large amount that isnt needed is. The descriptions apply
to North American lighting, which is not the same as ours. The
occasional error doesnt matter as most of it isnt really relevant to
choosing, fitting or fixing fl lights.

What you need to know comes down to a few things, presumably each of
which can be googled:

- circuit diagram of glow start fluorescent fitting (almost all british
lights are glowstart, with some being electronic. The various other
types used in NA are rarely found here.)

- how goddamn horrid cool white tubes are

- repair sequence, covered in previous reply

- the different glow starters, theyre not all compatible

- the fact that with the right type of circuitry, tube and installation
they can look every bit as good as filament lighting, but regrettably
most fl installs are crude and ugly.

- which tubes to choose and which to avoid, different for all fl versus
mixed lighting.

- the once semi-popular idea that fl lights should be left on when not
needed is a myth

I wrote a piece in the 90s explaining the different tube types and how
to do good installations, but I doubt I could find it. Google for
trough and shelf fittings.


NT