Electric shower tripping MCB

[jupiter77]

Newly installed Triton T80 8.5kW shower. The shower is tripping the MCB after about 5mins of use since it was installed. It’s on an 40A MCB which feels warm to the touch after it trips. Appears to be 6mm cable, the consumer unit is less than 18m away. No sign of water leaks, completely dry inside the case. Trying to get the guy who installed it to come back and fix, would be good to know possible causes/remedies before being fobbed off.

 

[flameport]

It’s on an 40A RCD

Please add a photo of that device and the consumer unit it's installed in.

 

[jupiter77]

Please add a photo of that device and the consumer unit it's installed in.

Added

 

[terryplumb]

That device is an MCB ,not an RCD.
Are you sure the shower is 8.5kw ? The 40amp breaker isn't going to be tripped on overload by an 8.5kw shower alone ,it would trip if there is a short circuit though.
The MCB's on that board don't appear to be fitted very well ,and are askew. Why someone would fit 2 from another manufacturer is anyone's guess.

 

[jupiter77]

That device is an MCB ,not an RCD.
Are you sure the shower is 8.5kw ? The 40amp breaker isn't going to be tripped on overload by an 8.5kw shower alone ,it would trip if there is a short circuit though.

Ok thanks will try to amend my OP. With a short circuit would it be likely to run for 5 mins before tripping?

 

[EFLImpudence]

With a short circuit would it be likely to run for 5 mins before tripping?

No.

 

[terryplumb]

It's a possibility ,But very unlikely. Something else is going on.

 

[DetlefSchmitz]

Check the kW rating on the plate on the underside of the shower.

 

[flameport]

Loose connection at the MCB in the consumer unit.

 

[jupiter77]

That device is an MCB ,not an RCD.
Are you sure the shower is 8.5kw ? The 40amp breaker isn't going to be tripped on overload by an 8.5kw shower alone ,it would trip if there is a short circuit though.
The MCB's on that board don't appear to be fitted very well ,and are askew. Why someone would fit 2 from another manufacturer is anyone's guess.

Check the kW rating on the plate on the underside of the shower.

Can confirm it’s 8.5kw

 

[EFLImpudence]

Is this new shower replacing one which did not trip the breaker?

 

[jupiter77]

Is this new shower replacing one which did not trip the breaker?

No, it’s an entirely new en suite, including the swa brought from the supply and consumer unit.

 

[EFLImpudence]

Right.

Installer back to get it working, then.

 

[Murdochcat]

SWA cable ?

 

[jupiter77]

SWA cable ?

Steel wire armoured, the heavy cable going in to the consumer unit.