A friend is letting us use their 17th century cottage in Cornwall for a few
days this coming holiday, in exchange for me fitting a replacement for her
very old electric shower heater, which is leaking and beyond economical
repair. This existing shower is fed via approx 3.5m of 6mm T&E cable, via a
ceiling mounted, pull cord, isolatiing switch, and the cable is buried in
the wall for probably 2.5m of its total length. Don't know until I get there
what size fuse/mcb is fitted in the CU. What is the maximum rating (kw)
shower I can connect to this size cable?
Thanks, David.
( Part pee.....yeah, I know!!)

In article ,
DavidM wrote:
A friend is letting us use their 17th century cottage in Cornwall for a
few days this coming holiday, in exchange for me fitting a replacement
for her very old electric shower heater, which is leaking and beyond
economical repair. This existing shower is fed via approx 3.5m of 6mm
T&E cable, via a ceiling mounted, pull cord, isolatiing switch, and the
cable is buried in the wall for probably 2.5m of its total length.
Don't know until I get there what size fuse/mcb is fitted in the CU.
What is the maximum rating (kw) shower I can connect to this size
cable? Thanks, David. ( Part pee.....yeah, I know!!)

http://www.tlc-direct.co.uk/Technica...ltageDrop.html

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*If we weren't meant to eat animals, why are they made of meat?

Dave Plowman London SW
To e-mail, change noise into sound.

DavidM wrote:

[...] and the cable is buried in the wall for probably 2.5m of its
total length. Don't know until I get there what size fuse/mcb is
fitted in the CU. What is the maximum rating (kw) shower I can
connect to this size cable?

If clipped-direct conditions apply to the whole cable run (i.e. no
thermal insulation, no grouping with other cables, no conduit or
trunking) you can take the current rating to be 47 A, which means a
maximum of 10.8 kW at 230 V, supply and fusing permitting.

( Part pee.....yeah, I know!!)

It sounds as if you are doing a direct replacement, which is not
notifiable. It would of course be prudent to carry out insulation
resistance and Zs test on the circuit though, as well as testing any RCD
that may be fitted. Also check that the supplementary bonding is OK,
particularly if there's no RCD.

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Andy