Electricity is dangerous and can be hazardous. In doubt? Call a qualified electrician.
Preparing flex for connection
You will require a sharp knife to strip the flex.
Lay the end of the flex on a firm surface and with the knife cut lengthways through the sheathing to the end of the wire, ensuring not to cut through the sheathing of the inner flex.
Pull back the outer sheath and make a cut at the fold to remove the outer sheath. N.B. if the outer sheath is braided fabric, (such as that found on electric fires, irons) it is best to wrap a piece of insulation tape around it to stop the end of the fabric from fraying.
Once the inner conductors are exposed they can also be stripped. This is best done with wire strippers, although it can be done carefully with wire cutters.
With wire cutters adjust the screw to the desired thickness of the conductor you are stripping and then insert about 1-1½cm (½in) into the cutters, squeeze the handle and remove the insulation, repeat for both or all three conductors.
The bare conductors that are exposed are made up of many strands of copper wire, these should be twisted together using pliers to tidy them up and keep them together.
If the earth wire in a flex is not insulated, i.e. a bare wire, it is best to insulate it from the point it leaves the outer sheath to the point it is connected, this will ensure that the bare wire does not touch anything it shouldn’t.