Inductive prox wiring practice
Inductive prox wiring practice
(OP)
Literature with 2 wire universal voltage inductive proximity sensors shows control power arriving at a relay coil (A1), then a wire (call it B)from A2 out to the prox, returning from the prox to complete the circuit to the neutral conductor. So, wire B, though not technically a neutral, is separated from 120V by the relay coil, limiting the potential fault current.
There's going to be a bunch of these 2 wire circuits, in EMT conduits, tapped at aluminum conduit bodies. Do we need a ground wire, and do we have to figure out how to bond it in the conduit bodies? What color should wire B be? Would this be relatively "intrinsically safe" wiring, or would it be if we changed to 24VAC? Or 24VDC?
There's going to be a bunch of these 2 wire circuits, in EMT conduits, tapped at aluminum conduit bodies. Do we need a ground wire, and do we have to figure out how to bond it in the conduit bodies? What color should wire B be? Would this be relatively "intrinsically safe" wiring, or would it be if we changed to 24VAC? Or 24VDC?





RE: Inductive prox wiring practice
No it will not be intrinsic safe unless its approved for that and it is supplied by an Intrinsic Safe barrier,
RE: Inductive prox wiring practice
I'm thinking in general of proxes, laser or ultrasonic sensors, pressure transducers, etc. - small, low voltage stuff frequently connected up in conduit bodies & dropped out through nylon strain reliefs. I've seen such things put together without the bond I know is required (for power wiring anyway)in any junction box where a splice is made - just wondered if there's a V or VA threshold below which it's actually code to do it that way. 24VDC PLC I/O wiring & components especially are often very compact, not much room for typical bond termination. Or say, for instance, a remote E-Stop button in its own metal enclosure, connected to a main panel by 50 ft of EMT conduit - ground wire & bond terminal required . . . ?