Protecting cable on external light

I would like to change the ancient bulkhead light fitting outside my back door (which has not long since had new wiring and switch fitted when the property was refurbished), to a modern security light so we can see to put the key in the back door lock.

The problem is the cable will have to be extended by a few ccentimetres using a terminal strip and so far as I can see it will be exposed to the elements where it comes out of the wall into the new light.

My question is do I need to use special cable and how do I protect this short run of cable from the elements

Would something like this help
http://www.tlc-direct.co.uk/Products/LB9025.html

Its difficult to comment without seeing the job really but you should avoid using a connector strip and use crimps, they will provide more protection than a connector strip - then buy some heat shrink wrap and cover the all the cables (in the corresponding correct colour). This will give it some added protection but will need to ensure that both ends of the heat shrink covered.

Depending on how short your cable is you should also out some mechanical protection in place such as a piece of conduit to protect the cable from damage. The better way would to be change the cable totally and use a short length of SWA where the cable is outside and use a outdoor junction box like this one - http://www.allaboutelectrics.co.uk/ip65-terminal-junction-box.html - to terminate the cable from the house and run the swa to the light from there.