Hi All,
Would like to hear everyone's interpretation on the requirements for Electrical Isolation in IEC 60079.14 clause 8.2 which require that means for isolation shall be provided for all circuit conductors, including the neutral. My understanding of the requirement to isolate all conductors is to reduce the probability of an incendive spark occuring inside the area due to cases like common neutral wiring and potential rise in the earthed circuit conductors in the event of a ground fault.
1) For instrumentation supplied via PELV supply, i.e. earthed 0V ELV supply:
a) Do you provide disconnect terminals for each conductor in the instrument loop? including 24V and 0V?, do you provide a 2 pole breaker on the load side of the DC power supply, or even a 2 pole breaker for each instrument?
b) Do you also isolate earth conductors? For example, if an earth conductor was disconnected from an appliance, and simultaneously an earth fault occurred near the point where the earth conductor was bonded, this could create a spark at the end of the cable inside the hazardous area.
2) For low voltage supplies:
a) Do you provide means to isolate earth conductors for LV supplies for the same reason as item 1) b) above? Switching the earth conductor for an AC circuit would not be allowed under my local wiring regulations.
Thanks
Would like to hear everyone's interpretation on the requirements for Electrical Isolation in IEC 60079.14 clause 8.2 which require that means for isolation shall be provided for all circuit conductors, including the neutral. My understanding of the requirement to isolate all conductors is to reduce the probability of an incendive spark occuring inside the area due to cases like common neutral wiring and potential rise in the earthed circuit conductors in the event of a ground fault.
1) For instrumentation supplied via PELV supply, i.e. earthed 0V ELV supply:
a) Do you provide disconnect terminals for each conductor in the instrument loop? including 24V and 0V?, do you provide a 2 pole breaker on the load side of the DC power supply, or even a 2 pole breaker for each instrument?
b) Do you also isolate earth conductors? For example, if an earth conductor was disconnected from an appliance, and simultaneously an earth fault occurred near the point where the earth conductor was bonded, this could create a spark at the end of the cable inside the hazardous area.
2) For low voltage supplies:
a) Do you provide means to isolate earth conductors for LV supplies for the same reason as item 1) b) above? Switching the earth conductor for an AC circuit would not be allowed under my local wiring regulations.
Thanks
