Earth Leakage CB

[ckolin]

Shower has been fitted for 15 year since before we moved in. It stopped working recently. Friend and electrician DIYer found that the earth wire and neutral wire had been swapped inside the shower(no one has ever been inside it). Result appears to be that the earth wire has eventually burnt out. Also burnt a bit of the joist in the loft. Seems we have been very lucky.
Why did it still work and should the CB or earth Leakage CB have tripped?????

He has repaired the wiring and swapped the earth/neutral wire to correct place and shower is now working fine. I am not confident in this now. I thought if something goes to earth it trips???

I'd appreciate an explanation of what happened here.

[ckolin]

Come on Jimbo, educate me! Why did nothing trip when the earth and neutral supply was reversed??
All that happened was the earth wire eventually burnt out, burnt a joist in the loft(looks as though it was lit) and the shower cut out.

Thanks to the whoever was watching over my family here.