17th edition bathroom earthing

[gardener1214388]

Bath or shower rooms:

Until 2nd July 2008 The 16th edition of the wiring regulations applied as well as the 17th edition. From that date all installations must comply with the 17th edition only. The new requirement is for all electrical equipment in bath and shower rooms to be bonded together along with all metal pipework. Supplementary bonding connects to the earth wiring of the electrical equipment inside the bath or shower room. It must not be taken back to the main earth terminal in the consumer unit

Question:
Why must it not be taken back to the consumer unit and where should the bathroom earth cable be terminated.

 

[Alarm]

Ends up at the light. IIRC.

 

[gardener1214388]

Ends up at the light. IIRC.

Cable ends up at bathroom light; that's what I thought. A colleague of mine tells me that it should go direct to the consumer unit via 16 mmm earth cable from consumer into the loft area then connected to the 6mm bathroom earth bonding. Any comments on that.

 

[Alarm]

Repost in electricals.