Electrical Wiring - Gremlins (Help Required).

[Dibs-h]

O/C is Open Circuit, opposite of short circuit, yes earth and neutral are commoned at the sub station and as necessary.

Roy.

Cheers Roy! I'm having a few intellectual intermissions lately! :shock:

Dibs

 

[Digit]

In electrical work Dibs there are rules as in any other science, and the principles are quite straight forward, but wiring a circuit can be somewhat more involved than the circuit diagram would suggest. But when in doubt draw it out and return to basic principles is a sound move.

Roy.

 

[OLD]

Reading the above, if the in line resistance is the device its self, then a capacitor across it should kill the volt drop and stop the flashing.
reducing the the exposure to induction may be difficult in practice and the problem may come back after further wiring alterations.
Your voltage test could be done on the faulty one with a conventional bulb temp.wired in to prove the connections.

 

[Dibs-h]

Update: stripped everything down to just the 1st light in the circuit - a std pendant with a CFL. Double checked all the connections and still got around 25V across the pendant terminals with the light off. No issues with the bulb.

Then added the line out back in to the pot light. Still 25v at both the pot light terminals and also the pendant. The pot light just wired up via a std 1 gang 2 way switch. Put the LED bulb in and the voltage across the pot light terminals dropped to around 15V and no flashing. Swapped the LED out for an El-cheapo LED bulb and the voltage dropped down to 5V (and no flashing).

Connecting the 3 core & earth with another 1 gang 2 way switch (and altering\correcting the wiring at the 1st 2 way 1 gang switch) caused the voltage across the pot light terminals to go upto 50V. I'd moved the 3core away (for part of it's run) away from other live wires. Used to be 70V across the terminals.

The Osram LED started flashing again. At this point I thought, why not wire the 2nd pot light in parallel with the 1st - after all the plan is to have 4 in parallel. Only had the el-cheapo LED bulb to put in the 2nd. No flashing and the voltage across either pot light's terminals dropped down to 5V.

Leads me to believe it is an induced voltage.

Checked the Neutral to Earth at some pendants and it's zero volts. The line up from the consumer unit doesn't go anywhere else, so I'm fairly confident there's no borrowed Neutral. Can't be 100% sure about the earth - so might get someone in to test that.

Plan is to fit the remaining 2 pot lights and fit them all with the Osram bulbs and then see what happens. Worse case is to get one of those suppressor thingies from RS and wire it across one of the pot light terminals.

The Osram LED GU10 is not consumer grade but professional grade and as such might be intolerant to induced voltages - whereas el-cheapo is consumer grade and isn't affected by them.

All the help and advice - very much appreciated. One more test to do tomorrow and that is to isolate the ring and see what happens to the induced voltage.

Many thanks

Dibs

 

[RogerS]

Essex Chris is correct. Somewhere along the cable run it is adjacent to another cable..could be ring..whatever. Anyway, it is picking up induced voltage (either capacitive or inductive). That is the usual expanauion for other types of lamps. No idea how LEDs are configured but suspect that is the cause. Cure? 100k resistor across the LED.

Not convinced it has anything to do with neutrals etc ...He only changed the bulb!

Wot we said.

 

[Dibs-h]

Essex Chris is correct. Somewhere along the cable run it is adjacent to another cable..could be ring..whatever. Anyway, it is picking up induced voltage (either capacitive or inductive). That is the usual expanauion for other types of lamps. No idea how LEDs are configured but suspect that is the cause. Cure? 100k resistor across the LED.

Not convinced it has anything to do with neutrals etc ...He only changed the bulb!

Wot we said.

Rog - cheers, I know, but felt obliged to test and confirm rather than have it go t1ts up.

Thanks

Dibs

 

[Dibs-h]

Update: Just to let folk know, wired up all 4 new pot lights (went down to 3 as 4 were too bright) and no issues with the bulbs flashing. If 2 bulbs are removed, the remaining one will flash. 2 bulbs together are also ok.

It seems with these particular bulbs (Osram Parathon) which give a very nice warm white and are on par with the 35w Halogen - must be more susceptible that other brands to induced voltage.

Many thanks to all the posters.

Dibs

 

[RogerS]

Dibs..it will be down to the internal electronics. The induced voltage will gradually charge up circuitry inside so that the bulb ultimately fires (flashes) at which point the charge (will be held in a capacitor somewhere or other) discharges and the light goes off.

Putting two bulbs in has the effect of damping the induced voltage because the impedance presented to the induced voltage is halved (assuming two bulbs are identical). This is equivalent to sticking a high value resistance across the bulb as suggested earlier.

Impedance can get confusing....viz using something like an Avo (which has a relatively low impedance) to measure your induced voltage will not show hardly anything (if at all). Because the low impedance is damping the induced voltage. But take an electronic multimeter ..which usually has a very high input impedance...then you will see a reading.

 

[Dibs-h]

Dibs..it will be down to the internal electronics. The induced voltage will gradually charge up circuitry inside so that the bulb ultimately fires (flashes) at which point the charge (will be held in a capacitor somewhere or other) discharges and the light goes off.

Putting two bulbs in has the effect of damping the induced voltage because the impedance presented to the induced voltage is halved (assuming two bulbs are identical). This is equivalent to sticking a high value resistance across the bulb as suggested earlier.

Impedance can get confusing....viz using something like an Avo (which has a relatively low impedance) to measure your induced voltage will not show hardly anything (if at all). Because the low impedance is damping the induced voltage. But take an electronic multimeter ..which usually has a very high input impedance...then you will see a reading.

Cheers Rog. Makes me wonder whether I should get an Avo type one as well! :wink:

Thankfully it's all working as expected. Wifey started asking why not make the stairwell lights match the hallway? :roll: At which point it was time to leg it!

Dibs

 

[Chrispy]

I'm sorry to dig this old subject up again but I think I may have an answer, Our landing light used to flash as did Dibs-h's but this morning SWMBO noticed that it has stopped and the only thing that I can think of at the momment is that I have recently removed the shaver transformer in the bathroom which had a electric tooth brush pluged into it, this was wired into the lighting circuit any way problem solved. So just wondered if this may be the same with yours.