The problem with not having the CPC in a ring as well is for testing: you won't easily detect an open on the CPC and so a reduction in its fault capacity & reliability.This is where I wasn't sure so suggested a 5 core, hoping someone would correct me if I was wrong.
But you could run an external CPC with 4-core SWA and have the CPC loop through the armour and back via the separate CPC (or 5th core).
[automerge]1590442220[/automerge]
Centre-off! You don't want the ring left open.This says its a 4 pole changeover isolator but the data sheet doesn't???? Or I'm tired and missing something.