Quick introduction & Question.....

[krisspark]

HI Guy's.....

First time posting on here but i have been watching and learning for a while.....

Quick bit about me.....i'm 29, been a qualified sparky for 10 years, served an apprenticeship, gained all the relevant qualifications and have now been self employed for the past 5 years......and touch wood....all is going well, although we could all do with some more work couldn't we!!

My question is this......i have a customer who is complaining of having her low energy lamp continuously flicker when it is off.....this problem is also tied in with an outside light but I'll leave that alone for now as I've not seen the job yet.and I'm sure there is a bit of fault finding needed for me to solve the problem.

What i would like to do is give the customer some info on the probable causes of this flickering lamp...i'm pretty sure it's to do with the frequency!? or the lamps ability to hold a small charge?! again I'm not 100% so it would be great if one of you kind gents or ladies could help me out here....

Thanks in advance

Kris

 

[a1]

Good Morning Kriss, and Welcome to the forum.

I would say - based on what you have said - that the two reasons that you have stated as a possibility, are what I would expect.

But there again - I am still a Training Spark.

Regards,

Admin.

 

[M107]

It's probably due to capacitance of the switch wiring. The cfl is just discharging after switch off.

Yep blank stare thats what I looked like.

If I can find it some kind soul on theIET forum sent me a write up on it so I'll post here for you.

 

[M107]

here you go had two replies in fact.

(1) it can be caused by wiring capacitance in parallel with the switch, -its actually surprising common, particulaly in 2 way circuits, to have a few nanofarrds of cable capacitance. If swapping the roles of the cores in the three core doesn't help (by placing earth between steady live and switched live, and reducing the coupling) then a permament mitigation is to have either a resistor or a capacitor in parallel with the lampfitting, to form a potential divider with the induced voltage. Typically 10 or 22nF is enough. A capacitor is probably preferred as it doesnt get hot, or confuse insulation testing.

The capacitor does need to be rated for continuous operation accross the mains, a modern polypropylene is probably appropriate, properly mounted and in a box of some sort if not in the luminaire body.

Essentially a relaxation oscillation occurs because the strike voltage is higher than the run, and the lamp has near infinite resistance when off, so the lamp's internal caps charge via the internal diodes fed by the stray wiring capacitance, until the striking voltage is reached, and then all flickers into life briefly as capacitors are discharged, then it all starts again.

(2)It is the capacitance accross the switch wiring this causes a few uA to slowly charge the reservoirs of the CFL electronics (as these contain a bridge rectifier and a reservois cap), then once the reservoir is full enough, the lamp driver starts briefly, and runs out of charge almost immediately, and the cycle repeats. - the effect is worse on a 2 way circuit because it is so long. The easy fix is a capacitor accross the L-N terminals of the affected fitting. Anything from a few 10s of nF to 1 Uf may be required, depending on the wiring length involved. Obviously the cap needs to be mains rated.

Dont know if the fella frequents here but these came from mapj1 (mike)

Hope it helps.

 

[krisspark]

Great stuff....

Thanks for the speedy replies....I thought i was on the right track i just couldn't put it into the right words! very impressive!

I'll be off then to get myself the right capacitor then.......

I'm going to the job tomorrow to fault find the outside light problem....she seems to think that when the outside light is activated the problems start at the low energy fitting......now going on the answers above there may be a couple of things at play here?! that when the o/side light is activated it is inducing a potential at the low energy fitting? either way it can be overcome with the right capacitor i hope!

Many thanks again

Kris

 

[a2]

Can't answer your question sorry, but i can welcome you.

Welcome to the forum Kris.

 

[Mr Sworld]

Howdy doody Kris.

 

[krisspark]

I Doody fine Mr Sworld.......nice easy monday just the way i like it!!

And hello to you Admin 2! ......bl**dy polite in here isn't it? ha ha

 

[extension15]

I've never experienced this problem........

 

[SPECIAL LOCATION]

Hi Krisspark

welcome from me!

not sure if you are a night-shift type poster....

or and early to bed...

If "early to bed" I think you will be part of TheorySpark's gang...

But just wait ......

Cuz if the weather stays fine..

Welshy says we can have a water fight on Saturday

Early 2 bed - Vs - Late night posters!!! ]

Pick your gang wisely young "Krisspark"

Remember the winning team get a treat laid on by "SurAlan" -- "Sugar"!

Back to your question...

I think the key points have been answered but I would just add..

I do know that many low energy lights specifically say not for use with PIR automatic operation...

Probably a bit of conflict of the electronics?

So it may be it both your low energy & Outside light PIR are a bit dodgy they are interfering with each other??

I would also add from my own personal experience some low energy lights are absolute biggest load of cr*p! out...

I have had several fail within a month.. either not work at all..

or just fire "dim" without full light i.e. the ole fluorescent "new starter" required type glow!

How frequently does the flicker occur.. i.e. is it easily reproducable on site?

If it is related to the cable route & always happens..

you could always try a little experiment putting the suspect bulb in a different fitting.. ?

See if the fault moves or stays with the location?

Anyway thats me done for now..

Once again. welcome m8

 

[Bclearnersparks]

Dont know if this helps but had a customer last year who complained of tv interference and breaker tripping intermittently when his outside Son lamp(Photocell) fitting was working. Also the lamp would sometimes be in a constant state of trying to fire up but never getting to full brightness.

Just turned out to be a loose connection and a few strands of the cable missing (TRS 1.5mm) at the fitting.

Its been ok since replacing the cable

 

[kme]

I think the answer to your op is well covered above m8.

I`ll just say that the late night team will win the water fight;

I`ve never had this flickering issue either Ext!?!?!

However, M107`s points are perfectly logical, and provide a viable causation.

and, oh yeah, almost forgot:

Welcome m8.

 

[SPECIAL LOCATION]

I think the answer to your op is well covered above m8.I`ll just say that the late night team will win the water fight;

I`ve never had this flickering issue either Ext!?!?!

However, M107`s points are perfectly logical, and provide a viable causation.

and, oh yeah, almost forgot:

Welcome m8.

Of course we will!

but don't deflate their optimism just yet..

oh by the way I popped into Woolworth's..

saw them big super-hyper-massive-big-soaker pressure-pumped water cannons?

Steptoes got em back at his yard..

I want the Pink one..

but there was a very nice turquoise twin tone colour one that would match with those very skimpy swimming shorts you got KME!

 

[a1]

Oh, They're off again. :_|

 

[kme]

That`s horse racing, that is. :^O

How you gonna manage AD? ?:| ? :|

You on night shift, and wizzer on "early-birds" team???

No. Better idea. Put the "bird" on the "early birds" team, and we can all go get drunk, er sunk. :^O :^O

Must be our turn?????

SL; when did you see my jazzy shorts??

 

[a1]

No. Better idea. Put the "bird" on the "early birds" team, and we can all go get drunk, er sunk. :^O :^O

Sounds good to me Mate.

 

[steptoe]

That`s horse racing, that is. :^OHow you gonna manage AD? ?:| ? :|

You on night shift, and wizzer on "early-birds" team???

No. Better idea. Put the "bird" on the "early birds" team, and we can all go get drunk, er sunk. :^O :^O

Must be our turn?????

SL; when did you see my jazzy shorts??

you left them lying in hercules stable you prat,

Im sure youve damaged that horse phsycologically.!!!!

bl00dy moron.

 

[SPECIAL LOCATION]

That`s horse racing, that is. :^OHow you gonna manage AD? ?:| ? :|

You on night shift, and wizzer on "early-birds" team???

No. Better idea. Put the "bird" on the "early birds" team, and we can all go get drunk, er sunk. :^O :^O

Must be our turn?????

SL; when did you see my jazzy shorts??

When you took em off to lend to Theory cuz he wanted to surf the Severn bore on the last high tide?

Mind you...

you were pretty far gone m8..

how many gallons had you drunk?

Good job them police didn't stop with you walking around in the buff! :O:O

It was the same day when wizzer had arrived in them really bright day-glow yellow shorts... Cuz admin2 was worried if we lost him..

"make sure you don't loose sight of him" thats what we were told!

 

[kme]

you left them lying in hercules stable you prat,Im sure youve damaged that horse phsycologically.!!!!

bl00dy moron.

When you took em off to lend to Theory cuz he wanted to surf the Severn bore on the last high tide?

Mind you...

you were pretty far gone m8..

how many gallons had you drunk?

Good job them police didn't stop with you walking around in the buff! :O:O

It was the same day when wizzer had arrived in them really bright day-glow yellow shorts... Cuz admin2 was worried if we lost him..

"make sure you don't loose sight of him" thats what we were told!

I don`t know which of you two is dafter anymore?

Maybe we need a daft poster vote???

methinks meknows who would win ( and it isn`t either of you!) :^O :^O:^O

 

[krisspark]

MMMMMMMM...............

Decisions......decisions.......never thought I'd have to pick sides so early......

But seeing as i am yet again posting early ( waiting for said customer to finish her school run) then maybe i am early bird sort or.........then again, i go on late at night as well?!...............so maybe........I'll sit on the fence for now and watch and observe the strengths and weaknesses of my fellow competitors!

Once again thanks for the replies i'll let you know how it went