On a related topic, John Rumm wrote:
There are also requirements for segregation of high and low voltage
circuits (or provision of adequate earthed screening. See 528-01-01,
and 02

Is SWA cable considered "adequate earthed screening" in this context?

I'd appreciate comments on a plan to run an SWA mains cable to an
outbuilding, along with several other cables, using a broad trough
covered by 600x600 flagstones to make a path.

The cables would simply be laid in the open trough, on a bed of pea
gravel to prevent stone cuts, running the SWA along one side and keeping
all the other cables as far away as possible. Then the flagstones would
bridge over the whole lot, resting on two parallel runs of block edging
(heavy load bearing is not a problem in this particular location).

Hopefully the SWA itself would be deemed to meet the requirement for
"earthed screening". In addition there will typically be at least 1ft of
physical separation plus four layers of insulation between mains and
signal conductors.

Conventional deep burial of the SWA is not a practical option here,
because we're on rock - even the proposed shallow trough will be very
hard work. Overhead conduit is not an option either. The flagstones
would seem to meet the requirement to prevent anyone from accidentally
digging into the SWA, at least as well as deep burial could.

All in all, I think this method would be more than adequate in technical
terms, but I'd very much appreciate comments from the regulatory
experts.



--
Ian White