Glowing fluorescent tube when turned off?

[rawzone]

I have just replaced a fluorescent tube and when the new tube is turned off you can see glowing gas movement within the tube. When I checked the connections the black wire is showing some current when the switch is turned off and when the lighting circuit is turned off?

I have since changed the switch to no avail that was also showing some current when the lighting circuit is turned off?

Can anyone help on this?

Could it be a fire hazard?

Many thanks for any answers.

Richard

 

[RF Lighting]

Does it glow for ever or just for a few seconds after it's switched off?

 

[rawzone]

The tube glows forever after it is switched off.

 

[flameport]

Could be that the switch is in the neutral rather than line, and the glow is due to capacitance between the tube and the metal casing of the light fitting.

 

[rawzone]

The switch is a double switch with the red live cable going to com and the link going to the other com. The black neutral cables go to the 2 nr L1 connections.

One side of the double switch could be disconnected because the light fitting was taken off the other end and replaced with some blocks.

Does that help re the switch?

 

[rawzone]

Could be that the switch is in the neutral rather than line, and the glow is due to capacitance between the tube and the metal casing of the light fitting.

Hi Flameport,
is there a way I can correct the wiring if what you suspect with the switch wiring is correct?

 

[Taylortwocities]

It may be due to a faulty or a lack of earth in the lighting wiring.


Also, I was curious. When you said:

When I checked the connections the black wire is showing some current when the switch is turned off and when the lighting circuit is turned off?

I have since changed the switch to no avail that was also showing some current when the lighting circuit is turned off?

What did you use to measure the current?
How did you connect it in to the circuit?

 

[JohnW2]

What did you use to measure the current? How did you connect it in to the circuit?

Good questions - I wondered myself. Do I perhaps feel a 'screwdriver' coming on?! ... not that any of this answers the OPs primary questions.

Kind Regards, John

 

[Lectrician]

DIYers often seem to say "current" when they mean "voltage".

I would put my money on the switching taking place in the neutral, which may be due to how it is connected in the fitting, or could be due to reverse polarity prior to this part of the circuit.

 

[bernardgreen]

What type of "tube" is it ? A long straight tube or a coiled tube in a compact flourescent lamp ( CFL ) ?

Many CFLs will glow or otherwise appear to be partially lit when they are switched off because they can use the small trickle of current that by passes the OFF switch via capacitive coupling in the cable to the switch to create some light.

Lamps with filaments do not have this problem.

 

[rawzone]

You are right in your assumption that I used a testing screwdriver to test for current/voltage, that was done by touching the cable when the circuit was turned off at the consumer unit, but to my surprise the black wire was still showing live.
The glowing in the 5ft tube has only become apparent since the tube was changed after the prevous tube died. By the way the tube in question has been checked on another light fitting and found to be ok.

I have now removed the tube from the fitting fearing it not to be safe, am I over reacting?

I am having a kitchen refurb and rewire after xmas so is it best in the meantime to just use a lamp for lighting?

Thanks for all responses

 

[XtraRaptor]

Maybe you should read upon your "test equipment"

//www.diynot.com/forums/viewtopic.php?t=18444

Are you sure that your switch is double pole?

 

[rawzone]

I have since checked that the earth cable is attached to the back of the metal switch box.

Hope that info helps.

 

[JohnW2]

Are you sure that your switch is double pole?

From what the OP has told us, we can be pretty certain that it is NOT double pole (it's a 2-gang SP switch), can't we - and that is what one would expect of a lighting switch.

Kind Regards, John

 

[riveralt]

The switch is a double switch with the red live cable going to com and the link going to the other com. The black neutral cables go to the 2 nr L1 connections.

One side of the double switch could be disconnected because the light fitting was taken off the other end and replaced with some blocks.

Does that help re the switch?

I take it you mean that the 'black neutral' cable is actually the switch live rather than a neutral.
Except on relatively new and specifically designed switches proper neutrals at the switch are normally connected together in terminal blocks and not in the L1 terminal.
If you have a switched live at the switch then you need to check the terminals at the lamp unit - most will have a live, neutral and earth terminal on the unit itself.
If this is the case then at the lamp unit you may have an additional terminal block containg the live loop, the neutral loop and earth loop.
With the circuit dead, check that all the terminals are tight.

//www.diynot.com/wiki/electrics:lighting:rose
It would be helpful if you could photograph and upload the wiring configurations of your light switch and the lamp unit itself.