Contact an electrician - there's a wiring fault (faults) somewhere on the lighting circuit. A potential of 180V suggests that you've lost 50 to 60V somewhere i.e. The Black (or Blue) Wire you call a neutral is not a neutral - it's carrying a voltage.
240V divided by 4 is 60V - I suspect 4 lamps wired in series - which is bizarre. I think that you may have been wiring several lights and have made basic errors.
Take care...
Peccavi
March 2010
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