DIN rails with insulators

Dear,

i was looking at a requirement from consultant stating that "the DIN rails of the PLC and RIO panel shall be installed with the insulators"

I need to understand what it is needed for if possible and if it is really necessary.

thanks a lot!

charbel

The opposite is the normal requirement.
Most PE terminals makes the connection to earth via the DIN rail.

edit: The backplane alu "rail" for an S7-300 PLC also is used to make the earth connection for the modules that need earth, including the CPU.

i do use insulated din rails to connect all grounds coming from shielded cables. This way i only have to break one connection to check if the shields are not connected anywhere else.
for digital this is also very handy to check if there is anywhere a leak or short to ground.
If a short is present the current in the shield can get very high, thus giving interference.
so yes please do, and have all these rails connected on one point in each cabinet.

ok thank you shooter.