Electric shower problems

[jessiekat]

I have just fitted an electric shower in my bathroom, all the plumbing is fine and the wiring has been done exactly like instructed.
When I switch the shower on, it runs on cold and high flow without a problem - as soon as I turn the dial to activate heating up the water it cuts out and trips.
Any ideas why? Willing to check anything, no suggestion is silly!

 

[BigJon]

Can you post pictures up of the connections at Shower, switch and Consumer unit (fusebox).
Hard to tell without more info, could be anything really.

 

[jessiekat]

Of course, will get them up tomorrow.

 

[Taylortwocities]

..........and also tell us the make, model and power rating of the shower (in KW)

 

[jessiekat]

It is a Bristan Smile 8.5kW. I'm not living at the house it's fitted in at the moment as I'm doing it up, but will gather more info and pictures tomorrow