Triton T80z

I would suspect a faulty connection, however I would getback to the builder, if you start tampering with it you may invalidate theguarantee.

 It sounds to me like faulty wiring or a faulty element.

In the first instance I would have the installer back to check and if everything is OK then phone Triton and they will send out an engineer who will replace or repair the unit.

Strange that it is not on the parts list however here is the link to the Triton micro switch.

 http://www.showerdoc.com/shower-spares/trito-22003230-triton-microswitch-(2-pin)-22003230

 Unfortunately there is nothing that is a direct swap.

However....... Triton has recently brought out the T80Z this shower has been designed round being a retrofit unit  (Tritons word not mine!)

The pipe work can be brought in from almost any position and there is a reasonable amount of space for cable entry from most positions.

Here is the link.

http://www.showerdoc.com/new-showers/triton/electric-showers/ZTRITO-SP8008ZUFIT-Triton-T80Z---8-5kW-(White-Chrome)

See Video at the foot of the page

You need a 15mm copper compression nut and olive.

I think you need a new pullcord switch.