543.6.1 the protective conductor shall be incorporated in the same wiring system as live conductors (re: overcurrent protection)

Perhaps it is the aspect of where 'best' the routing of conductors - particularly for lighting - that I am overly fussing about _*in relation to that Reg and associated others*_  when not necessarily running wiring 'together' or in 'close proximity' as detailed. The conductors are all in the same joined-up containment system as a whole, but might not be all together in the same segment at various points.

I used a pvc wiring containment example, because with steel the CPC aspect is somewhat resolved by default, via the various interconnected paths along the steel containment.

For a virtual example: some 20m away from the CU [over-current protective device] is an multi-module lighting grid switch and the most direct route from CU is along the trunking - which runs around the perimeter - along one edge of a wall to the switch.

One might presume, being direct route, to run a line conductor from the cu straight to the switch and then run the switched-lines from each switch module which then would veer off at various points, via different segments of trunking/conduit, to the each of the lighting unit banks. Keeps the number of conductors at the switch minimal.

To ensure a CPC is at the grid switch position, the CPC would run from the CU to the switch (with the line feed).

q1) would/should there then be a set (one for each switched line) of CPC's from the switch, along the same route as *each* of the switched-lines, or perhaps just run one 'running' CPC from the switch (or even from the CU ?) to each point by any efficient route ?

The neutral doesn't need to go to the switch, so could run an entirely different [efficient] route to the switched line(s) along sections of trunking/conduit from the cu to each of the lighting unit banks.

q2) would/should a CPC be also run along with the neutral in this case ?

Regards

Habs

NB: Of course one could adopt a loop-in approach if equipment etc permits, which keeps all the conductors together.

You do not want to be running any live conductor (line or neutral) on its own in a steel (ferrous) containment. It might get hot.

521.5.1

Of course a line feed down a steel conduit drop to a switch and its switch line back up again creates a cancelling effect of any magnetic fields around the two wires. But you would not want to run just a live wire singly along a steel conduit route.

Lighting cable is quite inexpensive so cost is a minor issue.

Z.

You do not want to be running any live conductor (line or neutral) on its own in a steel (ferrous) containment. It might get hot.

521.5.1

Of course a line feed down a steel conduit drop to a switch and its switch line back up again creates a cancelling effect of any magnetic fields around the two wires. But you would not want to run just a live wire singly along a steel conduit route.

Lighting cable is quite inexpensive so cost is a minor issue.

Z.

Thank you Z.

Getting hot issues aside, my scenario from the outset was not concerning steel containment,  I can't see how your response addresses specifically  q1 or q2 from my last post...how would you wire a supply feed to the grid switch and then on with the various switch-lines in the [2-plate approach perhaps] scenario I presented out of interest, if you think that approach incorrect ?

if a diagram is needed and interest not waning, I will draft one if it helps picture it.

Approaching both steel and pvc containment with a consistent 'best' approach seems sensible. 

www.youtube.com/watch

I would be inclined not to make the ends of the wires too long as that is wasteful. Also, I would mark the switched lines to make final connections quicker and easier, especially at switches where there are three brown wires.

Also, 521.5.1 refers to ferrous enclosures, (see definition for enclosure) so where single wires enter a metal box or luminaire base through a hole,  the regulation applies, although with small currents the heating effect will, in practice be negligible.

Z.