Running 4 core armoured cable to power shed

[mikex]

I am connecting a 4 core armoured cable to a fused outside connection terminal and to a mini RCD consumer unit in the shed to run 2 sockets and a light. The cable has 4 2.5mm wires (Black, Brown, Blue and Grey)plus armoured wire sheathing. I have been told that I just connect 3 wires and ignore the 4th & sheathing. However I read somewhere that I should earth the sheathing..Can somebody please advise the correct wiring method.

 

[ban-all-sheds]

You must earth the armour.

You must use proper external SWA glands.

You must install the cable safely.

You must ensure that the cable is the right size to avoid excessive volt-drop.

If you've got a CU at the shed end you must ensure that you don't get discrimination issues with one in the house.

Are you aware that this is notifiable work? See here: //www.diynot.com/wiki/electrics:part-p