New light fitting and Energy saving lamp

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I have just replaced a ceiling rose, cable and lampholder.
I then attached a new 20watt energy saving lamp.
It works o.k.
However, when I turned the lamp off, we noticed that the lamp pulsed with light every 15 secs or so, with the power off, I tried another similar older lamp but that seems to be fine.
Any suggestions as to why this should happen please?

tia
 
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It is normally due to inductive or capacitive coupling with the supply or switching cables. (In layman's terms un-energised cables are picking up a slight voltage/current from nearby cables)
 
I saw this before and it was damp running down inside the wall into the back of the light switch.
 
The cable from the ceiling rose to the switch is source of the problem.

There is capacitive coupling between the two conductors ( live and switched live ) across which a small amount of energy is able to pass. This small trickle energy is stored in the lamp's ballast circuit until it is enough to light the lamp in a short flash.

In an ordinary ( filament ) lamp the trickle of energy flows through the filament to neutral but is far far too small to have any noticable affect on the lamp.
 
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There is capacitive coupling between the two conductors ( live and switched live ) across which a small amount of energy is able to pass. This small trickle energy is stored in the lamp's ballast circuit until it is enough to light the lamp in a short flash.

Just asking out of interest - does this imply a 'problem' that can be/should be remedied by (for example) replacing the switch cable?

The low energy lights in my house did the same until I had a complete rewire of the lighting circuit. I assumed it was a faulty cable somewhere...
 
Thank you all for the response.

We have three bedrooms upstairs, a bathroom and a landing, except for the bedroom in which I removed a small 3 lamp spot, and replaced it with a rose, holder and esl, I have had energy saving lamps in use for years, and have not seen these lamps flash at all.
I put the same lamp into the holder on the landing, and bedrooms, it flashed on the landing and another bedroom.

If I had not changed the rose, lamp and holder in the first instance, and if they all had conventional lamps, I would not have known that something was not quite right, so what should I be looking at?

thank you
 
I should also have said that I very much appreciate anyone that takes the time to advise me.

I really appreciate it.
 
The other bedroom where the lamp flashed - are there two switches controlling the light fitting?

What you're experiencing is perfectly normal. A couple of my fittings do it. I have all energy saving lamps and a few 2 way switching arrangements. The cause of the phenomenom is the long runs of parallel live and dead cores in the cables.

If you can imagine, a bit of electric jumps across the cores, and slowly drifts into the light.

The filament in a standard lamp discharges this straight to neutral. But a CFL doesnt have a filament, and it must build up so much charge before it can jump across the tube, which is exhibited as a flash.

Its normal and wont harm the lights.
 
Putting a resistor and capacitor in series across the lamp often solves the problem as this allows the trinkle of energy to by pass the lamp.

Edit

values given before may be wrong, I will update this when values confirmed.


See later posting
 
Well, what can I say? for the last few hours I have been thinking I may have to empty the loft, remove all the flooring, find a
trustworthy electrician, have the house rewired, go begging for some money from somewhere, or take out another morgtage.

I have only one switch for lighting in any room except for the stairs.

Do I understand what you guys (or dolls) have told me? something that I could NOT use in Court :))

The situation I have is not dangerous,
Its normal and wont harm the lights (or the house, or me?)
Putting a resistor and capacitor in series across the lamp often solves the problem as this allows the trinkle of energy to by pass the lamp. (the trickle is still there but the lights won't flash).
If this is the case, I feel a very happy bunny.
 
It is worth checking that there is a properly connected earth conductor in all of the cables in the lighting circuit.
It should be there and connected but sometimes it has become disconnected. The lack of an earth can exacerbate the problem.
 
Taylortwocities,
Thank you for your comment, non of the lighting circuit in the house is earthed. I have lived here since it was built in 1964, the wiring in the house was checked by a electrician a few years ago who said it was sound.
My comment, meant jokingly of course about, "something that I could NOT use in Court" was a rather stupid thing to say.
I take on board the fact that any opinions and advice are offered in good faith, and I really appreciate that, I am quite satisfied that the wiring is sound, that the fitting of the new rose is o.k., and understand the reasoning given in all of the responses.
Am I digging a hole here:))
 
If none of the lighting is earthed then you must not use any metal switches. Also any metal light fittings must be double insulated (aka Class II fittings). These are also identified by the double insulated symbol: this is a square box with another box inside it.

The fact you have no earths will be the main cause of your induction problem with the new lights.
 
The values to use are

Capacitor 0.047uF micro Farads 250 volts AC
Resistor 100 ohms

Which come pre-packaged as a contact suppressor from RS Components

RS Stock No. 206-7847
Manufacturer Evox-Rifa
Manufacturers Part No. PMR209MB5470M100

There are other sources
 
thank you very much for the advice given, and I will have a look for RS Components, should I install these components in only the fittings that flash?

and one final question, I have used energy saving lamps for a number of years, why has this suddenly come to light do you think? if you will excuse the pun!

thanks again.
 

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