Grunff wrote:

Dave Jones wrote:

Taken from On Site Guide, Table 6D1 Method 3 (enclosed in conduit on a
wall in trunking etc.) 6mm 2 cables single phase, current capacity =
41 amps

Method 4 (enclosed in thermally insulating wall etc) 34 Amps

Method 1 (clipped) 47 Amps

I was reading from the same hymn sheet :-)

Wrong hymn sheet, 6D1 (4D1A in the BS) is for singles, not twin & earth.
For T&E look at Table 4D5A (6F in the OSG). For flat cable in
insulated walls you choose from Method 6 (enclosed in conduit in
insulated wall) - 32 amps - or Method 15 (installed directly in an
insulated wall) - 35 amps. Method 1 (clipped direct) is the same rating
though - 47 A.

But is it safe to make that assumption? Given that we don't know that
there isn't a 5m run of cable running through loft insulation, is it
safe to assume? I'm not being argumentative - I'm geniuinely curious
about the correct way of deciding this.

Go into the loft and have a look. If the cable's surrounded in
insulation the effective rating will be 20-something amps and trouble looms.

--
Andy