flashing LEd spots

[Mitch]

Hi everyone,
can any one help with this little fault? i have been fitting new spot lights in a kitchen, In the process i found a earth fault, the earth disconnected in one part of the daisy change of the existing house wiring, so I fit the spots in the kitchen connect the earths back up only to find the disconnected earth has 120v in it, now i have spent the day tracing the fault and can't find it as yet but in the process the system has been made live and with the earth connected, the spots in a different room flash on and off at a steady rate with the switch off. could this be a fluorescent light fault in another room?
any Ideas?
Mitch.

 

[BillyTheSparks]

I have had a similar problem, although mine didn't involve a disconnected earth. Mine was due to induced voltage from the 2way switching.

The earth that you have reconnected, what circuit is it from/to?
Is the voltage in the earth constantly?
Is the other end of the earth connected into the cu properly?

 

[Mitch]

I have had a similar problem, although mine didn't involve a disconnected earth. Mine was due to induced voltage from the 2way switching.

The earth that you have reconnected, what circuit is it from/to?
Is the voltage in the earth constantly?
Is the other end of the earth connected into the cu properly?

Hi billy the sparks,
the earth is in the lighting circuit the same one as spots.
it voltage is constant but will disappear if i trip the mcb for the upstairs sockets then I get earth continuity back on the live earth.
yes checked the earth connections and Ive followed the cables and can't find a cross between the upstairs sockets and the down stairs lights, as i have rewired the rest of the lighting circuit for them so i know its not connected.
there is only on two way switch and that's off the upstairs lights, so i don't know if its possible but it has fluorescent and low energy lamps could I be getting a discharge though the earth from one of them?

 

[fylthespider]

had 2 similar problems with cfl's.
1 problem was induced voltage on live (due to very long cable run?).
2nd problem was voltage on live due to water leak into switch (from bathroom).
in both cases, with dilog tester or my kt62, couldn't see any voltage on live, when i hooked up an electronics style multimeter could see around 60v. current of a couple milliamps.

i think whats happening is electrical testers have low input impedence which shorts out the induced/leaked current showing no voltage (and hence no fault).
electronic meters have very high input impedence (>10mohms) so can 'see' the voltage.

now, the ballast in cfl's and some led transformers have capacitors in.
the very low voltage and current will charge these caps up over few seconds until they reach a point there is enough charge to light the cyl or led, which then discharges the cap and the whole thing starts again..... flash flash flash arrgh!!!!!

now i may well be wrong but electronics mate of mine agrees it possible correct explanation, and the cure/proof was to temp connect a gls lamp in parallel to the cfl. flashing stopped.
theory being the low (cold) impedance of gls bulb shorted the leakage current out.

ultimately, better quality cfl's sorted the problem out.

hope thats some help, and if anybody know any better, let me know cos these sorts of things do my noodle in.

 

[BillyTheSparks]

now, the ballast in cfl's and some led transformers have capacitors in.
the very low voltage and current will charge these caps up over few seconds until they reach a point there is enough charge to light the cyl or led, which then discharges the cap and the whole thing starts again..... flash flash flash arrgh!!!!!

now i may well be wrong but electronics mate of mine agrees it possible correct explanation, and the cure/proof was to temp connect a gls lamp in parallel to the cfl. flashing stopped.
theory being the low (cold) impedance of gls bulb shorted the leakage current out.

ultimately, better quality cfl's sorted the problem out.

hope thats some help, and if anybody know any better, let me know cos these sorts of things do my noodle in.

This is exactly what I found with my problem, I got around it by wiring a modular contactor into the switched live of the circuit and that stopped any cappacitance to the lamps.


Now with this earth; if you haven't got 2way switching on these lights then that should rule that out.
If you trip the upstairs sockets the voltage goes away, but do the lights still flash with that circuit off?
If they are still flashing with that circuit off then perhaps disconnect the fluorescents/CFLs from their respective circuit to see if that stops the flashing.

Have you checked the neutrals of the circuits and at the cu to ensure that they are all ok?
You could have a loose neutral that is causing induced voltage through the cable to the cu then through the earth, also check the earth at the consumer unit
Have you checked the Ze of the property and the earth bonding??

A lot of questions all over the place there, but thinking and typing what came into my head.

 

[bigspark17]

i had a similar problem in a kitchen once.. it was as simple as L-N reverse polarity.. worked fine when switch in on position flashed in off position.! check that