Homebrew PCBs

Hi all,

I'm looking to measure a 300 volt line and drop it to 5 volts.   One 
of the many problems is that there is also the potential of a 15kV 
spike on the line.

I would appreciate any help finding parts that can withstand the high 
voltage.   And any links to information on what to watch out for.


But, for this group.  Does anyone have any ideas on how to determine 
the slices in a PCB around chips ?   I would like to isolate the 15kV 
pulse from the rest of the board.   A second board is a very good 
possibility.

VERY open to suggestions.

Dave