polarity problem

[scott 123]

adding to a lighting circuit before i started did a polarity test at jb in loft (acting as Rose) found the following
L - N 230v
L - CPC 24v
N - CPC Ov
cant figure it out
any advice where to start looking would be apriciated

 

[HandySparks]

Start by checking continuity from the JB back to the board. L-N, L-E, N-E, or do them individually with a wander lead.

 

[telectrix]

broken or unconnected cpc. IMO.