Flickering Light

[sleevit]

Hi all,

I had a call out from a lady who thinks she has a ghost. The hall light flickers at night (and presumably during the day) when it is switched off. I have heard about this before as it is a low energy lamp. She insists that it happens with normal lamps too but I'm not convinced (tried one and it didn't do it).

The residual voltage (with lamp removed) is 50 Volt which seems very high. The light is on the landing (normal pendant) and has a 2 way strapper to downstairs (3c+e between switches). If I disconnect the strapper the voltage drops to about 20.

I haven't had the floor up yet. I have tried turning off all the other mcbs and that made no difference.

I have guessed that the strapper is running alongside the main feed to the upstairs lighting and inducing a voltage but it seems high.

Please, all thoughts and theories welcomed.

 

[Andy™]

for your 50v, does your meter have a high or low resistance? if its high resistance, inductance can give readings like that, use a low resistance meter and voltage will drop to (almost) 0v

a filament bulb cannot 'flicker'

 

[Nicky Tesla]

he meens impedance

 

[SPECIAL LOCATION]

for your 50v, does your meter have a high or low resistance? if its high resistance, inductance can give readings like that, use a low resistance meter and voltage will drop to (almost) 0va filament bulb cannot 'flicker'

he means impedance

Or combining the two...

for your 50v, does your meter have a high or low impedance? if its high impedance, inductance can give readings like that, use a low impedance meter and voltage will drop to (almost) 0v

a filament bulb cannot 'flicker'

(unless the ghost is turning the switch off & on fast) ; \ :^O

I have seen these low energy jobbies flicker...

after its been on for a while, turn it off.. and flicker we go!

I saw one continue to flicker for 5mins+ at a job before Christmas..

(may have gone on longer but I got bored waiting & watching)

this was a road with no street lights so when it went dark it was black as a bag outside..

so dim flickering stood out even brighter.

Have seen normal lights flicker when loose connection in rose..

a) someone walking across upstairs room

B) wind or draught causes movement in pendant

both vibrate loose wire in rose!

 

[Andy™]

he meens impedance

your right, i do mean impedance

 

[Evans Electric]

Wonder if the earth wire in the 3c+E is actually earthed ? I've had a few strange readings and stray voltages and neon screwdrivers lighting up on the earth when that happens. Low energy lamps are a bit weird anyway !!

Non connected Earth wire could carry an induced voltage from the live strapper to the dead strapper. Perhaps !!

Deke

 

[SPECIAL LOCATION]

Wonder if the earth wire in the 3c+E is actually earthed ? I've had a few strange readings and stray voltages and neon screwdrivers lighting up on the earth when that happens. Low energy lamps are a bit weird anyway !!Non connected Earth wire could carry an induced voltage from the live strapper to the dead strapper. Perhaps !!

Deke

Earth wire shouldn't be connected to ANY strappers! ? :|

Sticking just one probe of a cheepo meter on a 240v live wire will give a reading around 50v!

 

[Evans Electric]

Earth wire shouldn't be connected to ANY strappers! ? :| Sticking just one probe of a cheepo meter on a 240v live wire will give a reading around 50v!

What I meant ,Specs, was if the earth wire was NOT connected to earth , so they usually carry an induced voltage,which often fades out when a neon driver is poked at it, but could, possibly, transfer that induced voltage to the other strapper, through the switch in its off possition and to the lamp, hence, flicker, flicker via the control gear . All pure guesswork, conjecture and pie in the sky of course.

How about a faulty switch then, full of carbon spash crap and arcing some voltage to the lamp,

Come on, I'm doing my best here, give me a break

 

[GreekIslandLover]

I did read something on this topic on the iet forum a couple fo days ago whereby Philips LE lamps seem to be the worst offenders. I had one this week, and the punter had worked out that all she had to do is to put a "Proper" lamp in rather than a CFL and the flickering stopped.

 

[bassman]

What I meant ,Specs, was if the earth wire was NOT connected to earth , so they usually carry an induced voltage,which often fades out when a neon driver is poked at it, but could, possibly, transfer that induced voltage to the other strapper, through the switch in its off possition and to the lamp, hence, flicker, flicker via the control gear . All pure guesswork, conjecture and pie in the sky of course.How about a faulty switch then, full of carbon spash crap and arcing some voltage to the lamp,

Come on, I'm doing my best here, give me a break

Tend to agree faulty switch or neutral open on the circuit somewhere.

 

[Apache]

for your 50v, does your meter have a high or low resistance? if its high resistance, inductance can give readings like that, use a low resistance meter and voltage will drop to (almost) 0va filament bulb cannot 'flicker'

wack it on a cheap, knackered generator and I assure you it can

 

[sleevit]

The strapper earth is good (I done a loop test at the downstairs switch and that was fine).

I will try changing the switches (or a bit of choc block for a temporary link).

The meter is a fluke so shouldn't be too bad.

Thanks for the replies. I think I'll have to get some boards up and see how close the strapper is to the lighting feed cable. I'll re route it if I have to.

 

[SPECIAL LOCATION]

The strapper earth is good (I done a loop test at the downstairs switch and that was fine).I will try changing the switches (or a bit of choc block for a temporary link).

The meter is a fluke so shouldn't be too bad.

Thanks for the replies. I think I'll have to get some boards up and see how close the strapper is to the lighting feed cable. I'll re route it if I have to.

?? :|

99.9% Its the lamp!

I know of loads of installations where the landing-hall strappers all run bunched with other cables following the main route from hall up to loft!

They should all have bucket loads of induced voltages from shower circuits & ring mains etc.. BUT THEY DONT!

Don't get too confused with this 50v reading,

Is it old wiring with a "Shared neutral" between lighting circuits?

That can give an apparent voltage via another path back to the CU through a bulb.

Take all the bulbs out dis all wires out of CU for the circuit.

If it is a proper induced voltage you should read something via your light circuit back to another suitable earth ref point, (e.g. extn lead from socket).



ES screw fitting bulbs can flicker when the springy contact at the very back looses its bounce! due to age & heat!

 

[SPECIAL LOCATION]

If pendant fittings..

physically swap two pendant around in the house..

the ficker position with a non-ficker..

see if the fault moves

OR..

How far away is the job?

borrow the light bulb and bring it home,

try it at you own house for a day or two.

Both easier & cheaper than lifting floorboards and possibly not finding anything?

 

[crystaljohn]

I have exactly the same problem with a flickering CFL when switched off on a customers upstairs landing.

The pendant is 2 way switched.

Any advice appreciated.

 

[Lurch]

I have exactly the same problem with a flickering CFL when switched off on a customers upstairs landing. The pendant is 2 way switched.

Any advice appreciated.

1. Start a new thread rather than digging one up from over 18 Months ago and tagging a vaguely related question on the end.

2. It's the lamp.

 

[justinwhite]

had this before myself it was the light switch it was very old and somehow was letting 34volts thro swapped it job done 0 volts

 

[crystaljohn]

The reason I tagged this question on the end of the thread was to see if there had been a definite solution to the problem, as there was none indicated.

I will change the switches, and try another CFL.

Thanks for your advice, much appreciated.

 

[steptoe]

NO

chuck the CFL and put a normal lamp in,

CFLs are NOT always suitable as a straight swap, no matter what the bumf may have you believe.

 

[crystaljohn]

I am curious when you consider them suitable as you say they are not always suitable.

I would still like to understand the reason for the flickering though, does the starting characteristics of the CFL cause more arcing and deterioration of the switch contacts ?