CPC as a functioning return path!!!???

[spud1]

Had a really weird one this week.
Customer complaining about getting shocks from a power shower.

Inital investigations showed reaction from my volt stick from the shower hose! (All be it not full mains)

Took the lid off and the plumber who recently installed the shower had connected the neutral and earth the wrong way around!

Odd thing was that the power shower still worked..? Checked the fused spur in loft where power shower was fed from and seemed to be connected correctly (all be it very untidy). Not certain which circuit it was fed from but there was limited RCD protection for the house. (sockets only)

My question is:: Why didn't anything trip out!? how did the shower function with the CPC as the return path? Only thing I can think is that it using the common connection at the PME terminal but still doesn’t explain why it didn't trip the MCB at least... what do you guys think?

 

[Avo Mk8]

If you consider the MCB, it's only monitoring current In the live feed. It won't know the current is returning via (E) rather than (N)!
But an RCD should see the difference. Perhaps there wasn't one in this circuit?
Not odd the shower worked considering (N) and (E) are connected together somewhere - a good job they are!

 

[LastManOnline]

If you consider the MCB, it's only monitoring current In the live feed. It won't know the current is returning via (E) rather than (N)!
But an RCD should see the difference. Perhaps there wasn't one in this circuit?
Not odd the shower worked considering (N) and (E) are connected together somewhere - a good job they are!

There is either no rcd on the circuit or its a malfunctioning rcd. The mcb did,nt trip because it was, nt being overloaded. The shower is, nt faulty. Its likely a TNC-S system so the earth wire is in effect acting like an alternative neutral