how to find a neutral
 

hiya everyone could someone out their help me please,when i install a boiler etc and a new room thermostat is to be fitted it can be very confusing as to what wires are what,plus nearly always only 3 core has been installed and use the earth as a switched live,i can where possible change it to a 4 core with the correct colour coding.

this is my problem and really hope someone out there can help

please can someone help how do you get a true test to find the neutral i would be extremly grateful if someone could just clear this frustrating question up please.

all the best


gary