Here's one for you

[down2earth]

Thought I'd get round to testing the sheds having moved in about 2 months ago, there are two sheds on 4mm SWA coming from a 20A MCB on the main CU, the bottom shed is about 40metres away. As soon as I put the Megger on to do a ZS it came up saying there was a Live Neutral swap somewhere, on further investigation where the SWA comes into the shed the previous occupant has gone straight into a 13A FCU, from there it feeds one double socket and a lighting circuit (fused down to 3A). Anyway, he had swapped the L and N on the feed side of the FCU, the load side is OK, my question is, shouldn't this have tripped the MCB in the CU? or is this to do with them having the same potential.

All thoughts gratefully received.

Down2earth

 

[Amp David]

It would just mean that everything in the shed would of had reversed polarity.

Single pole devices would of been switching the neutral and not the line.

 

[jmtisme]

no polarity reversal wouldnt trip an mcb

 

[telectrix]

MCB will only trip when it sees an overload current suffisient to exceed the trip threshold.