is it safe to connect a 6 mm cable to a 2.5mm cable

[littlespark]

I wonder if the builder downgraded the shower mcb to suit 2.5……

What am I saying!!!!!

 

[adonis2]

Thanks , I'll ask him to put it in a enclosure

Put the builder in an enclosure

 

[brianmoooore]

Just to echo what others have said: Do not let this person touch your electrics again.
If he is incapable of joining two wires together safely, then what is the rest of it like? Is there an isolator for the pump? What is the fusing for the pump?
I strongly recommend that you let a professional electrician look at this.