UK Identifying live, neutral and earth in outdoor festoon lighting

Richard Cook · Jun 4, 2024

I bought some outdoor festoon lighting a few years ago and the 2 pin connectors (male and female) have corroded so I’m going to splice the connectors together using heat shrink butt connectors. Each run is 5m with a male and female 2 pin connector at each end. My first thought was that this would be a 2 min job but it turns out none of the wires are labeled so it’s tricky to work out which wires are live, neutral and earth once the connectors have been cut off.

See a few photos attached.

I can connect one end (thankfully the one end that isn’t damaged) to the “starter plug” which has a transformer (31v) so can voltage check each cable and plug it in.

At the other end, with the now exposed wires, what’s the best way to find the live, neutral and earth? I’ll then need to Wago, for testing, this to the other run but how do I work out which is live, neutral and earth on that run? Trial and error? What am I looking for? Would it trip the RCD until right? What about the transformer? Any way I can avoid breaking it with testing?

littlespark · Jun 4, 2024

What is the writing on the transform? If it’s 31v, it might be DC, with a plus and minus rather than AC live and neutral. Unlikely to have an earth.

Is there any writing on the wires? There might be one that has a dotted white line to identify it.

Is the male and female plug and socket keyed? As in, can it only fit one way?

Richard Cook · Jun 4, 2024

Also when plugged in the lights don’t light up. I’m thinking the three wires must loop back when they’re normally inside the male/female connector? If one side is connected to the plug then I thought they would light even though the other end has been cut off?

Richard Cook · Jun 4, 2024

littlespark said:
What is the writing on the transform? If it’s 31v, it might be DC, with a plus and minus rather than AC live and neutral. Unlikely to have an earth.

Is there any writing on the wires? There might be one that has a dotted white line to identify it.

Is the male and female plug and socket keyed? As in, can it only fit one way?

Thanks for the reply!

There’s nothing on the transformer. The writing seems like manufacturer stuff only. I’ve attached a bunch of photos. And yep it’s keyed.

[ElectriciansForums.net] Identifying live, neutral and earth in outdoor festoon lighting

littlespark · Jun 4, 2024

I don't see a transformer, so i don't know where you are getting the 31V from.
The label says 220-240V, so that's mains voltage.

Are the lamps removable? (unscrew)... if so, the centre pin will be live and the screwed outer will be neutral.... if you have something to measure continuity... If they are bayonet cap lamps, with the 2 pins... then it wont matter which way round the L and N are, as the lamp can go in either way.

Take extra care if these are mains voltage.... unplug before poking about in lampholders.

Richard Cook · Jun 4, 2024

littlespark said:
I don't see a transformer, so i don't know where you are getting the 31V from.
The label says 220-240V, so that's mains voltage.

Are the lamps removable? (unscrew)... if so, the centre pin will be live and the screwed outer will be neutral.... if you have something to measure continuity... If they are bayonet cap lamps, with the 2 pins... then it wont matter which way round the L and N are, as the lamp can go in either way.

Take extra care if these are mains voltage.... unplug before poking about in lampholders.

Thanks again.

I know what you mean but it has that big block on the starter plug (ConnectPro® 2m Starter Cable, Black or White - Powers up to 7600 LEDs - https://www.festive-lights.com/2m-starter-cable-with-uk-plug-black-or-white) but think I’ve been confused with ConnectGo vs ConnectPro (what I have).

The bulbs are all molded closed so that doesn’t help. I think if one light goes they all go if that helps understand the circuit.

If I plug in one end it should come on but it doesn’t… but if I multimeter each wire is there a reading I should be looking for for each one?

MDJ · Jun 4, 2024

Richard Cook said:
I bought some outdoor festoon lighting a few years ago and the 2 pin connectors (male and female) have corroded so I’m going to splice the connectors together using heat shrink butt connectors. Each run is 5m with a male and female 2 pin connector at each end. My first thought was that this would be a 2 min job but it turns out none of the wires are labeled so it’s tricky to work out which wires are live, neutral and earth once the connectors have been cut off.

See a few photos attached.

I can connect one end (thankfully the one end that isn’t damaged) to the “starter plug” which has a transformer (31v) so can voltage check each cable and plug it in.

At the other end, with the now exposed wires, what’s the best way to find the live, neutral and earth? I’ll then need to Wago, for testing, this to the other run but how do I work out which is live, neutral and earth on that run? Trial and error? What am I looking for? Would it trip the RCD until right? What about the transformer? Any way I can avoid breaking it with testing?

you use a multi meter or ohm meter and do a continuity test on the 3 conductors.

westward10 · Jun 4, 2024

They are identified by that label as Class II so I'm not sure one of the conductors would be an earth.

littlespark · Jun 4, 2024

westward10 said:
They are identified by that label as Class II so I'm not sure one of the conductors would be an earth.

Also says “made in china” so there’s your answer

Richard Cook · Jun 4, 2024

MDJ said:
you use a multi meter or ohm meter and do a continuity test on the 3 conductors.

Thanks so much for this. I've got a multimeter so will look this up. Any suggestion of what I'd be looking for between each test?

KungFuTurkeyLeg · Jun 4, 2024

Only reason I can think of for the 3rd wire is to keep the other lights if one goes. Like the posh Christmas lights from 20+ years ago. My own festoon lights are 230v that have a similar connector. Unless you have crocodile clips to do it hands free, I really wouldn't recommend trying to measure the voltage by hand incase it is 230v.

Best doing resistance by clipping onto one of the plug pins and then tapping out the other end. If you get a low reading on one of them, that will be connected to the pin your clipped onto.

Look at that black box at the start of the run and see if it has an input and output voltage stamped into it.

Richard Cook · Jun 4, 2024

KungFuTurkeyLeg said:
Best doing resistance by clipping onto one of the plug pins and then tapping out the other end. If you get a low reading on one of them, that will be connected to the pin your clipped onto.

Can you point me in the direction of finding out more about this?

westward10 · Jun 4, 2024

Is there only two pins in that plug and no other metal contacts?

Richard Cook · Jun 4, 2024

westward10 said:
Is there only two pins in that plug and no other metal contacts?

Ah I see what you mean.

The starter cable is 3 pin uk plug to that black box to a female end (accepting two pins).

The 5m length of lights has those three wires exposed (which was 3 wires going into a 2 pin male connector) and then a female end.

Richard Cook · Jun 5, 2024

KungFuTurkeyLeg said:
Only reason I can think of for the 3rd wire is to keep the other lights if one goes.

I spoke to customer service and yes you cannot replace the bulbs but if one bulb goes it doesn't break the sequence (unless the bulb connection itself breaks) so I'm curious.

They also said "The wires are positive and negative wires which make up the AC-DC" which doesn't help me.

UK Identifying live, neutral and earth in outdoor festoon lighting

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