Heat damaged cable and Pressure Relief Device [PRD] on a 8.5kW electric shower. Shower unit replaced with 7.5kW model as supply cables only 6mm. Many modern shower units are draw too much current, above the supply cable capacity. This leads to overheating and possible fire in the home. 1100 fires anually, in UK properties, caused by electrical faults. Always get a Competent Electrician to check bathroom equipment. DIY electrical work costs lives.