Outside Light Wirring

[unclepim]

Need some help!

I have an outside light which is wired into a light switch which is part of the downstairs lighting circuit.

I have replaced the light with a 300w hi/lo light with sensor but not sure if I have wired it up correctly as it keeps tripping out

When I removed the old light I had two cables attached to it wired like this

Both earths to the earth terminal
Both lives to one terminal
One neutral to one terminal and the other to a separate terminal.

The new light only has three terminals, I have put the two earths, two lives, and two neutrals into the relevant terminals on the new light.

When I turn the power back on the light works fine, but if I use the switch to turn it off then it trips out the circuit.

What have I done wrong, do I need a new fuse for the fuse board?

Regards
Kim Bryan

 

[JohnD]

When I removed the old light I had two cables attached to it wired like this......
One neutral to one terminal and the other to a separate terminal....

...The new light only has three terminals, I have put the two ...neutrals into the relevant terminals on the new light...


...What have I done wrong,

You have made the mistake of thinking that a black wire is always a neutral. One of them is a switched live. So you have connected the neutral and the switched live together. You have made a short-circuiting device.

see //www.diynot.com/forums/viewtopic.php?t=37582

you will have to reassemble the wires as they were before. If your new lamp has insufficient terminals you will need a choc block or other terminal strip, which you will have to enclose to protect it from rain or contact.

 

[unclepim]

JohnD

Many thanks,

The only problems Ihave now is identifing which one of the black wires is the switched live and which one is the neutral from the power supply.

Any suggestions?

I am also assuming that this is a spur off the lighiting ciurcut as I only have two wires.


Regards
Uncle Pim

 

[JohnD]

Pop up to the high street and invest £8 or so in a digital multimeter (not one from a motoring shop that might only be safe to 12v).

Provided you can work safely, not balanced on a metal ladder, and not at risk of touching anything else live or earthed, you will find that when set to the 250v AC setting, you have (about) 240v between L and N (usually red and black, or brown and blue).

One of your blacks will be the switched live, and will have no voltage against the red, but 240v against the other black. The voltage will come and go when the light switch is tuned on and off. Mark this wire with brown or red sleeving that you can also get at the electrical counter.

BTW when you are at the electrical counter, also buy some green and yellow sheathing, if you do not already have some. This is used to cover the exposed parts of the bare copper earth wire when the cable sheath has been removed.

Be sure to turn off the power before making any adjustments, or disconnecting and reconnecting anything. It is safer to do the wire-testing thing if you turn off the power first, then put each wire into a separate terminal in choc-block insulated connector strip, then use your tester probes on the screws in the strip. This reduces the risk of any wires touching each other or you. This strip is available at the electrical counter, it is very cheap.

 

[ban-all-sheds]

do I need a new fuse for the fuse board?

Yes, or a piece of 5A fuse wire if it's a rewirable fuse.

You might also need a new switch.

 

[unclepim]

MAny thanks,

Why are these things never simple!!!

 

[ban-all-sheds]

Lighting circuits are simple...

Circuit cable runs from one lighting point to another...

Cable runs to switch and back to light...