Replacing Fluorescent Light with LED

Firstly I'll declare myself as a DIYer with some practical and theoretical experience of electrical circuitry.

My neighbours, who I've frequently done bits and bobs for in the past, asked me if I would replace two existing adjacent flourescent lights in their kitchen - with two LED battens.  I replaced the first one - everything tickety-boo. I then fixed the second - slight flicker - and then nothing. Current ok through the live feed. I fixed a pendant fitting to the live and neutral to test to see if there was light but that failed - although my neon screwdriver indicated there was current - both live and switched-live through the neutral. The LED bulb I used was ok in its usual fitting

Neighbour took the light back to the merchant (Buildbase) who, very oblingingly, provide her with a replacement - which they, apparently, tested before issuing it to her. On fixing  this one exactly the same thing happened - one flicker and then nothing. Could be two duff battens but I doubt it. The second light appears to be fed by a spur off the first. The first and successfully fitted light is the primary.

The fluorescent light which was originally fixed on the primary wiring had failed. The fluorescent that had been fixed to the 'current' problem position was working ok before I removed it.

Any ideas about what might be causing this malfunction, please.

PS The product is marketed by One Electrical Ltd. It's a Class 1, 240v 50hz, IP20 50w LED .

thanks for any info. and/or advice

Sounds like you have a broken neutral connection.  Check all the connections you have touched.

You really need suitable meters to verify continuity, polarity & voltage on all of your wires, a neon has very limited usage and is not an approve test instrument for electrical work. It cannot identify how much voltage is or isn't present on a conductor, as you simply have a glow to indicate a potential difference between the wire and your body. As Geoff suggests double check a wire hasn't broken off after you though you had connected it. Or that it is not trapped by the insulation rather than actual conductor itself. 

although my neon screwdriver indicated there was current - both live and switched-live through the neutral. The LED bulb I used was ok in its usual fitting  

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A neon cannot indicate current, when you refer to switched live through neutral, are you confusing a black wire from the switch thinking it is a neutral wire? e.g. you have connected a black switched live onto the neutral connector at the lamp?  Or if you really are getting a glow on the neutral with the neon, then the other end of that neutral wire is not connected. As the neutral should be at near earth potential similar to you body so neutral to body will not illuminate a neon.

Doc H. 

Check all your connections at the first fitting . 

Geoff1946 said:

Sounds like you have a broken neutral connection.  Check all the connections you have touched.

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Thanks for your comment. Neighbour is getting a qualified 'sparks' in to check the situation. Cheers.

Doc Hudson said:

You really need suitable meters to verify continuity, polarity & voltage on all of your wires, a neon has very limited usage and is not an approve test instrument for electrical work. It cannot identify how much voltage is or isn't present on a conductor, as you simply have a glow to indicate a potential difference between the wire and your body. As Geoff suggests double check a wire hasn't broken off after you though you had connected it. Or that it is not trapped by the insulation rather than actual conductor itself. 

A neon cannot indicate current, when you refer to switched live through neutral, are you confusing a black wire from the switch thinking it is a neutral wire? e.g. you have connected a black switched live onto the neutral connector at the lamp?  Or if you really are getting a glow on the neutral with the neon, then the other end of that neutral wire is not connected. As the neutral should be at near earth potential similar to you body so neutral to body will not illuminate a neon.

Doc H. 

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Unfortuantely, I only partially understand what you're advising. The wiring from the lighting circuit to the batten LED was straightforward so I'm beginning to suspect there was another reaosn for one of the original fluorescents not working - other than a failure of the unit itself. My neighbour is getting an electrician in anyway to do some maintenance work on a buliding she's caretaker of - so she can get him to check what's going on. I get what you're saying about the limitations of the neon tester. Checking the circuitry with an appropriate tester would determine the fault, but I'm not knowledgeable enough to do so without bringing an old brain up to speed on domestic electrical lighting circuitry. I guess if I took the floorboards up and isolated all the wiring running to and from the fittings I'd stumble upon the solution - but taking up t&g is a tad too dirty and hard work for my inclination. I'll let the younger guy do it. I wasn't getting paid for it! Thanks for your detailed input - much appreciated. best wishes - Chris