Flickering light

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I've just had the house rewired but have a problem with a flickering light. The landing light will occasionally flicker on although the two-way switches are off - it only happens for a few minutes every few days. Upstairs and downstairs are on a different circuit and I'm not sure which the landing light runs from. The electrician suggests we try a new bulb (it's an energy saver bulb) but I can't see how a faulty bulb would light if the switches are in the off position.

I'd be grateful for any advice on what the problem might be.
 
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From comments other posts about borrowed neutrals I would guess it shouldn't pass the testing for certification but the electrician has apparently issued a certificate. Shouldn't he have spotted and corrected it on testing?
 
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Energy saving bulbs often flicker when the circuit they are in has a lot of cable to and from switchs. There is a capacitive coupling from the live to switch live which allows small trickle of power to reach the lamp. The energgy saving circuit saves this trickle until it is enough to light the lamp for a very short flash. An incandescent lamp cannot store the trckle of power so does not have the same problem
 
pdcelec said:
sounds to me like a borrowed neutral
No it doesn't. Its a standard issue with energy savers. Very common and not a problem. Ours landing light does it. Charge builds up on the switched live until it is enough to arc across the lamp. This doesn't happen with filament lamps because they provide a direct (albeit high resistance) connection between switched live and neutral.
 
Crafty wrote: Charge builds up on the switched live until it is enough to arc across the lamp.

Once the bulb had flickered on once would this charge continue to build up to create a series of flashes over a number of minutes?

Contacted the electrician and he insists it's a faulty bulb.[/b]
 
frankman said:
Crafty wrote: Charge builds up on the switched live until it is enough to arc across the lamp.

Once the bulb had flickered on once would this charge continue to build up to create a series of flashes over a number of minutes?

Contacted the electrician and he insists it's a faulty bulb.[/b]
Some compact fluorescents are more prone to the flickering, but its not a fault. Many electricians will be oblivious to the phenomenon.

On a 2-way lighting circuit, you have a length of wire between 2 switches with a live and a switched live (dead) running side by side for sometimes quite some distance. This length of wire acts like a capacitor and charge (electrons) builds up on the dead switched live wire (which is connected to the lamp). This happens continuously whist ever the switch is off.

In a filament lamp, because there is a filament there is a constant route for the electrons to flow to neutral, and therefore earth.

However, in a compact fluorescent there is no filament, so the charge builds up in the circuitry of the lamp. After a certain amount has built up, it will flicker across the gas in the lamp to neutral. This is the flicker you see occasionally. Its completely normal and nothing, IMO to worry about.
 
i suggest getting the circuit tested to find whether it is the lamp or a borrowed neutral. No-one on here can give a comprehensive answer without seeing it. It could be any of the suggetions made on here[/img]
 
Put in a filament type lamp. If no problem, then flickering is due to electronics in energy saving type lamps.
 

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