LED Lights not working

[ThyJones]

Hi there,

I've purchased 6 of these lights: http://www.screwfix.com/p/robus-fire-rated-fixed-led-downlight-ip20-brushed-chrome-3-5w/50280

I have them linked in the following way,

Feeding from an existing lighting circuit joined in a junction box (JB), I go from JB > Light 1 > Light 2 > Light 3 and so on, and ends at light 6, no route back.

I turned the lights on last night, nothing trips on my main fuse board, but no lights come on (not a single one), I've tested power to each of the lights and each and every one has power. Each light is just wired light earth > cable earth, light neutral to cable neutral and then light live to cable live, that's it, an exact matching of colour cables.

At this point i'm stuck and not sure what to test. Any suggestions please?

Thanks

 

[EFLImpudence]

I've tested power to each of the lights and each and every one has power.

How have you done this and with what?

 

[Taylortwocities]

I've tested power to each of the lights and each and every one has power.

How did you test for POWER? You cannot have power unless there is current flowing. If the lights do not come on then I suspect there is no curent flowing!

What you need to check is for voltage. What voltage is shown at the light(s)?

 

[ThyJones]

I've tested power to each of the lights and each and every one has power.

How did you test for POWER? You cannot have power unless there is current flowing. If the lights do not come on then I suspect there is no curent flowing!

What you need to check is for voltage. What voltage is shown at the light(s)?

All I've basically done is test with a device similar to: http://www.screwfix.com/p/lap-ms8907-voltage-detector-pen/3222G?kpid=3222G&cm_mmc=Google-_-Product Listing Ads-_-Sales Tracking-_-sales tracking url&gclid=Cj0KEQjwlNy8BRC676-W0JezxbwBEiQA4Ydg0bicjSwL74HzQXV0c7-6fusN2u8uok3KcgqJ2VwBujMaAoEc8P8HAQ which lights up/alerts when there is voltage, which has been picked up on every cable going to each light.

 

[EFLImpudence]

which has been picked up on every cable going to each light.

Useless things.

Check all your connections again. No wires snapped or insulation in terminal.

As none of the lights works, start at the junction box.

 

[ericmark]

Voltage is measured between two points, normally we measure between line and neutral or line and earth. The voltage pen or neon screwdriver measures between line and your body which due to the mass of your body is some where near earth polarity. So all they show is you have line, they don't show you have a neutral.

Testing a neutral or earth is not easy, as you need some current to flow to show it is really connected to where it should be connected rather than a simple capacitive or inductive link to the surroundings. The device we use is a loop impedance tester which puts a small load onto the cables often just 25 mA so it will not trip the RCD but in doing that it can show where earth or neutral cables are not connected.

There are cheap plug in units for testing sockets around £50 but the electricians model is more like £250, in the old days I used an AVO Mk8 to test with, these had an ohms per volt setting for each range, so measure the voltage on the 500 volt range, then measure on the 1000 volt range, and if the 1000 volt range showed a higher voltage you knew that there was some high resistance in the supply. But the meters used today are more like the valve volt meters of yesterday and a chip compares the voltage without drawing current so very hard to be sure there is not a neutral fault.

However even though a voltage tester like this

uses very little current it in general is 100% better than a voltage pen which makes no contact. The idea of most voltage testers is to have no switch, so it can't be in error switched off, the idea is you test the tester with a know voltage source then test to see if dead, then re-test the tester, I know this does not apply with what you are doing, but they are designed to work with very little current so even the tester shown can show a circuit is live when it is not, or at least not enough current to do useful work, just enough to give you a shock.

The multi-meter should not really be used to prove dead, but it can be used to show voltage is there, and with a clamp-on type also show current is flowing. But I was dismayed to watch some 'A' level students trying to use a multi-meter in a Physics class and over 50% of the meters ended up with blown fuses where used incorrect. I am told 'A' stands for "Advanced" I hate to think what a normal person would do! As a result I am loathed to recommend using a multi-meter, specially as most are supplied with leads which are not suitable for low voltage (230 volt) work. However they are likely the cheapest option. That Martindale tester which is really the industrial standard tester for voltage costs around £44 but the multi-meter like this one is just £7.50

so it is very tempting to buy what if you know how to use it will do so much more. What we can't work out is your level of skill, if better than an 'A' level student then multi-meter seems the way to go.

 

[Taylortwocities]

Feeding from an existing lighting circuit joined in a junction box (JB)

One more possible gotcha. How do you know this is the feed of the lighting circuit?
If you used your voltschtick you could have easily picked a switch wire, and that will be missing an essential ingredient!!

 

[ThyJones]

Feeding from an existing lighting circuit joined in a junction box (JB)

One more possible gotcha. How do you know this is the feed of the lighting circuit?
If you used your voltschtick you could have easily picked a switch wire, and that will be missing an essential ingredient!!

Basically, turned the light on, tested voltage, which was present, turned fuse off on board, killed lights, and voltage if that makes sense.

 

[Taylortwocities]

Yes, but you would get the same result on the cable to the switch if you tested using your volt stick.
The switch cable has a live and a switched live, but no neutral, which may be the basis of your problem.
But there is no point going any further until you have an adequate test device.