Earlier this year I had to build a Current Transformer (CT) as part of a group assignment. It's rated 1Arms @ 50Hz with sensitivity 100mV/A with a terminating resistance of 12 Ω. The wire gauge was 1.3mm which was really thick. Our ideal sensitivity would've been something like ~150mV/A for the turns ratio 1:100 but by some miracle the core saturated at the higher end of the rated power and pulled the sensitivity characteristic plot into something fairly linear. If I was to do it again I'd make the turns ratio something like 1:200 and change the burden resistor.
blakefuller3 