On 31/01/2018 08:24, jim wrote:
Wrote in message:
On Tuesday, 30 January 2018 22:48:09 UTC, jim wrote:
Net result is so far I can't fit both "feed" cables into the
terminals on the rear of the boost timer that I want to
replace

Fit a double outlet cooker plate adjacent?

https://www.tlc-direct.co.uk/Products/AA45DCOP.html

Fits on top of an existing flush back box and has 2 x cable clamps for the outgoing cable to the boost switches.

Owain



Yes I think some sort of a junction box is looking like the
solution so far.

I don't think I've got any 4mm2 in old or new colours :-( & I'd
only need a foot or so..

I'm going off the 2.5mm2 feed idea, wouldn't that need fusing down
to be safe?

You have 6kW of load or 26A. 2.5mm^2 T&E is good for 27A in its "clipped
direct" or buried in masonry installation method. So much depends on the
detail of how its installed. (and also how warm it is in the cupboard
with the cylinder, and how much cable running at a potentially higher
than normal temperature)

You might find the worked example in this page worth looking at:

http://wiki.diyfaq.org.uk/index.php/...istics_of_load

Some two immersion setups are intended to run one heat only at a time.
(i.e. the top one to give boost of quick hot water, and the lower one
for a full reheat). Obviously that would be fine on your cable. Both at
once is a bit more marginal, although in reality is unlikely to cause
massive problems.

--
Cheers,

John.

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