Shower unit dims Isolator neon light

[numdel1]

G'day,

The isolator switch lights up normally.

When I turn the shower on, the isolator light dims, but, is clearly lit.
The shower unit does not light at all.

If I turn the shower unit off, the isolator returns to full brightness.

There are electrics at the shower unit, with the isolator turned on.

Does this indicate a problem with the shower unit, or the isolator switch?

Any help, much appreciated.

 

[EFLImpudence]

Loose or already burnt wiring in the switch or elsewhere.

 

[numdel1]

Loose or already burnt wiring in the switch or elsewhere.

No showers for me this year.

Thanks for your reply