"JennyC" wrote:

Hello JennyC

J 1) There had obviously been a short circuit and when we
J investigated saw that the wires were sort of dried out (if
J that makes sense) and frizzled at the ends. Could this be

If they looked burnt then yes, probably a bad connection.

Other possibilities include contact with polystyrene (sort of "melts"
the PVC) and mice (teethmarks).

J due to the really hot temperatures in the GH during the
J summer months ?? If so what should we do to stop a repeat of
J the problem ?? (I do use shading but it still gets HOT)

Temp increases the resistence of the wire, but I doubt it's getting
hot enough to damage the PVC coating itself.

J 2) Is there special wire one should use?

Normal PVC twin and earth is usually ok, but you really should have
that section protected by a RCD if its not already.

J 3) or special insulation ?

I'd be more worried about the load of that heater. If it's a biggy
then it might be too much for the wire, time to do some calculations
and bear in mind that the length of the run reduces the load the wire
can carry. uk.d-i-y is a good group for more detailed info on this
(about where my brain runs out, I'm afraid).

--
Simon Avery, Dartmoor, UK Ý http://www.digdilem.org/