Odd electrical problem

[Biggles]

The lights in one shower room have ceased to function when switched 'On', although the extractor fan starts normally. The light fitting consists of three G9 lamps suspended from a bar. When I removed the fitting from the beam and tested it, I found that there is no power present at the fitting. All circuit breakers are 'On'. Can anyone explain how this situation could arise, please? (and what to do to repair it)?

[RobertArthur]

The infamous domino connection somewhere in a back box?

Replace with Wago connectors. Finding these boîtes de derivation is not always easy.

Check backside of switch for loose connections.

[rabbit]

Robert are Dominos inherently less reliable connections?
Should one always use Waco instead
Thanks

[RobertArthur]

@ Rabbit, as soon as you insert several wires into a domino you create possible problems. These little screws have a tendency to loose their grip over the years. In many EU countries on the no/no list, sometimes only allowed to connect lighting. And sometimes someone has cut too deep into the plastic and goes into the copper of the wire. A little bit of mechanical tension does the rest in the long end.

French info. One remark about this information: there are also WAGOs accepting fil souple.

Test slots also available and a very small footprint.

[Biggles]

Thank you, Robert, for your response. I've no knowledge of Wago connectors - presumably they are available in the Bricos? The fitting has a 3-way domino (I know them as chocolate blocks) connector and, now that I have found the relevant cct breaker, I will have another look at it tomorrow in safety. Meanwhile, I'll check out 3M this afternoon for Wago connectors.

[RobertArthur]

Biggles, there are also lookalikes available. Personally I prefer the quality of the German made Wagos. Climate chamber testing these connectors including salt spray test, not too bad....Choco blocs, I try to avoid them as much as possible.

[Veem]

Thanks very much for your advice. Biggles managed (with my assistance, naturally) to test everything that needed testing and in the end discovered that all 3 bulbs in the fitting had blown! Perhaps a surge during a recent storm when he'd maybe left the lights on?

Bulbs are now replaced and all is back working again.

[RobertArthur]

Out of interest one question: in the beginning you measured a no power condition. How did you measure this?

1/ To avoid: only to be used as a screwdriver, never as a reliable test instrument. Because of its very high impedance it measures also induced voltages, several wires in parallel are enough to give you a false positive. A so called ghost voltage, not a hard voltage.



2/ You need a little bit of power consumption to be able to measure a "real" voltage. My father had a little 5 watt bulb (fridge type) with two wires and probes. Today a simple and reliable solution is the use of a low-impedance Duspol.



3/ Digital multimeters: very useful, but with their rather high impedance not for the electrician. There are multimeters offering you the best of both worlds including a special low impedance range. Fluke's LoZ range, see below. Also useful to test little coin batteries, is this CR2032 really 3.2 V or already tumbling down in capacity, down to 2.7 V or even further down the hill?

[RobertArthur]

@ Biggles, about these G9 halogen (?) bulbs: they get hot very quickly. They ought to be quite long lasting but high temperatures and voltage spikes will decrease life expectancy. The three of them losing the will to live at the same moment: perhaps the power surge during stormy weather as you mentioned. Nothing else damaged?

The G9 leds don't dissipate too much heat, the problem of voltage and current spikes remains. Promised life of about 15,000 hours, but.......About LEDs and the design of their drivers. Poor design can be a problem in LED bulbs.

Cheap light bulbs burn out faster. Not always: sometimes they outlive their triple A rated family members.

Dominos continued: twenty years ago Thierry and David published "Le grand livre de l'électricité". The Eyrolles publishing company had a preview of 13 pages at their website, freely accessible for everyone. Zooming in on one of these pages (238) something about the correct wiring of a domino.

[rabbit]

Robert I use one of these to test for a live circuit. Does it have the same issues as the screwdriver?

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