For what does PELV require protective conductor? And also what is differences between PELV and FELV?

For what does PELV require protective conductor? And also what is differences between PELV and FELV? Both of them require PE conductor

I'm not sure a PELV circuit requires a protective conductor at all - it may have one if you want (e.g. for functional reasons), but as far as I can see it's not actually required by regs. PELV circuits (unlike SELV ones) may be connected to Earth - but that connection need not involve a protective earth conductor - as it's not required for protection against electric shock as far as the PELV circuit is concerned. Any old means of earthing, or just a potential for fortuitous contact with earth (say lack of insulation on one pole in an earthy environment), would be enough to make a circuit PELV rather than SELV.


By comparison SELV circuits are definitely 'earth free' so may be preferred in some situations - e.g. where hazardous voltages imposed on your local "earth" connection (e.g. during faults on the LV system) might be a problem - say if your ELV circuit ran outdoors or otherwise beyond the LV installation's equipotential zone.


Both SELV and PELV systems require a safety source - i.e. something with protective separation between the ELV circuit any LV primary (e.g. the equivalent of a transformer with double/reinforced insulation between the LV and ELV windings) - so neither need worry about being exposed to mains voltage due to a trasformer fault. FELV on the other hand permits only simple separation - e.g. the equivalent of just single insulation between primary and secondary windings - so a single fault could impose mains voltage on the ELV circuit. Hence FELV circuits usually need to have insulation rated at the primary circuit's (e.g. mains) voltage. PELV and SELV circuits need only have insulation for their actual volatge (e.g. 12V).


  - Andy.

For what does PELV require protective conductor? And also what is differences between PELV and FELV? Both of them require PE conductor

I'm not sure a PELV circuit requires a protective conductor at all - it may have one if you want (e.g. for functional reasons), but as far as I can see it's not actually required by regs. PELV circuits (unlike SELV ones) may be connected to Earth - but that connection need not involve a protective earth conductor - as it's not required for protection against electric shock as far as the PELV circuit is concerned. Any old means of earthing, or just a potential for fortuitous contact with earth (say lack of insulation on one pole in an earthy environment), would be enough to make a circuit PELV rather than SELV.


By comparison SELV circuits are definitely 'earth free' so may be preferred in some situations - e.g. where hazardous voltages imposed on your local "earth" connection (e.g. during faults on the LV system) might be a problem - say if your ELV circuit ran outdoors or otherwise beyond the LV installation's equipotential zone.


Both SELV and PELV systems require a safety source - i.e. something with protective separation between the ELV circuit any LV primary (e.g. the equivalent of a transformer with double/reinforced insulation between the LV and ELV windings) - so neither need worry about being exposed to mains voltage due to a trasformer fault. FELV on the other hand permits only simple separation - e.g. the equivalent of just single insulation between primary and secondary windings - so a single fault could impose mains voltage on the ELV circuit. Hence FELV circuits usually need to have insulation rated at the primary circuit's (e.g. mains) voltage. PELV and SELV circuits need only have insulation for their actual volatge (e.g. 12V).


  - Andy.