In a IEC Zone 2, Gas Group area II-A Temperature Class T3 area classification, are barriers to be required for signals coming in from the field going to a control panel? If not, when are barriers required? Thanks all.

 

Barriers are not an automatic requirement in zone 2. You have to undertake a design review/risk assesment and decide what/how you are going to protect against explosions. "EEx i" i.e limiting energy is only one method available to you.

Normally zone 2 is simply "EEx n", "EEx d", "EEx e". "EEx i" is only mandatory for Zone 0.

 

Normally barriers are used to connect EEX i (ia: zone 0, ib: zone 1) devices. i means intrinsic safety.