What have I gone and done!?

[Keefa]

I have just fitted a new strip light in my loft, but when I tried it out it blew the upstairs lighting circuit fuse.
My installation is as follows:
I fitted a new 20A junction box on the lighting circuit (the cable running between two upstairs light fixtures) and linked that to my new light. I then wired from the light fitting down to the light switch.
When I refitted the fuse and switched back on at the fuse box the new light was working. When I switched it off it went off, but when I then tried to switch back on - nothing. I then discovered that I had blown the fuse for the upstairs lighting circuit.
I thought I was following the correct procedure but I've obviously done something wrong.
Another problem I have is that I do not have any replacement 5A fuses that will fit the fuse holder. The previous fuse is stamped BS1361 but all the fuses I can find are BS1362 (and are slightly bigger and so do not fit the fuseholder).
Can anyone help me please as the missus is none too impressed with my handiwork today!

 

[plugwash]

the fuse you wan't is a 5A consumer unit fuse which is slightly smaller than a plug fuse

http://www.tlc-direct.co.uk/Products/WYCFL5.html

im sure i've seen theese in at least one of the diy sheds (i think it was homebase but im not sure)

i've heared of people managing to get plug fuses into the holders before but i don't know how much force was needed

also if its a wylex board you could fit one of theese plug in breakers
http://www.tlc-direct.co.uk/Products/WYB6.html

finally as to your original problem it sounds like you have wired the switch accross the light rather than into the power feed for the light

 

[Keefa]

Thanks for the info about the fuse Plugwash.

Sorry if I'm being a complete dunce here, but can you lead me through this a bit more...?

My light fitting has live, neutral and earth connections. My lighting circuit has red, black and earth wires. What am I supposed to connect where?

Sorry to seem like such an idiot but the more I read the more confused I get!

 

[plugwash]

the black cable from the lighting cuircuit goes to the neutral of the light

the red cable from the lighting cuircuit goes to the red cable from the switch but does not join to the light. ceiling roses provide a block for this connection but in most other lights you will need a peice of terminal block

the black cable from the switch (which should be sleeved red) goes to the live of the light

 

[breezer]

just for you

the cables in the switch should be connected with choc bloc

 

[Damocles]

OK you have power coming in to your new junction box on red and black. Also i guess, going out again where you broke into the cable.

Next you should have added another red and black wire for the new switch. The red of this joins with the original reds. The black goes to a separate terminal in the junction box. ABSOLUTELY NOT WITH ALL THE OTHER BLACKS. This black switch return should be identified by putting some red sleeving or tape around it. Most probably you added the switch return to the others!!!!bang!!!! Or muddled up which is which.

Then you connect your lamp. You take the neutral supply for the lamp from the terminal where the original two blacks join. You take the live supply from the terminal with just the one black wire which has come back from the switch.

All the earths should be connected together on the fourth terminal. (this was a four terminal lighting junction box, wasn't it?)

It is possible you might have damaged the switch by shorting the circuit through it.

 

[plugwash]

whilst the two things you have posted are both valid and possiblly easier on a new install than what i suggested. what i suggested is the correct method to work with the cable routing he has already installed

 

[Keefa]

Many thanks guys. Your explanations make sense to me.
I'll try again tomorrow and hopefully get it right this time!