Looee,
If I may explain further...
The grounded conductor (sometimes referred to as "neutral") does indeed carry current, as should be either white or grey. If it is used as an ungrounded conductor in a switch loop or for a 240V circuit, it must be permanently marked with a color other than white, grey, green, or green with a yellow stripe.
In switch loops, it is also important to use the marked white wire as the unswitched leg of the loop, and returning the hot on the black wire.
