Neutral overheating on the off peak immersion

Hi Mike,
I have an ongoing problem with my pulsacoil 2000, the neutral cable connected to the off peak immersion heater appears to be overheating as when i go to use the shower or taps there is no hot water and upon investigation the cable is brittle and broken away from the connector, with the insulation also melted, i have stripped it back and re-connected but this only works for a period of time.
Any Suggestions?

Thanks a lot

Steve

Fit new cable complete
Buytl 1.5 mm 3 core cable
Twist the cores when stripped and make a really good connection.
Sometimes cable terminators are used design depending on heater fitted.
Ask at local electrical shop whom should advise you.

Replace cable and clean surface of neutral connection.