Hi all

Just a quick note/question regarding the external dimensions of 6mm T&E.
Our kitchen is a single storey extension onto the original property, so the
original cooker feed had been jointed under a bedroom floor.
As I was splitting the kitchen onto a separate ring and running new power,
lighting and earth cables, I decided to stick a fresh length of 6mm through
for the sake of good form (and also to remove a section slightly damaged by
recent plumbing works).
As I am not "allowed" to do work "in" the kitchen per se, I have run the new
cable as far as the kitchen loft and jointed to the old drop to the existing
isolator for now.
I have left enough spare in the loft so that it can be pulled down to a new
isolator when we finally fix a layout for the room.

So, the question......

The external dimensions over the insulation for the new cable were
significantly different (smaller) to the older cable.
So much so that we ended up checking the cable strands to reassure ourselves
that the new cable was actually 6mm!
This cable is new colours , but was an "off-cut" and therefore didn't come
on a labelled drum.
The labelling on the cable itself (from memory) said something like BASEC
6004 4 2005.
The number 4 in the middle was the concern - 4mm cable?

Anyway, having confirmed the conductor size at 6mm sq, why are the
over-insulation dimensions so much smaller?

Thinner insulation to cut manufacuring costs?
Thinner insulation to allow better heat disipation?
Thinner insulation because the modern materials used are superior?

Anyone got any other ideas?

I would expect that the length of cable removed was about 20 years old.

TIA

Phil