"Don Pearce" wrote

You can use that one spare connection for ground, but is that
something different from the one you already nominate as Earth? Not
too clear about that.


Having two parallel paths for earth reduces the possibility of the chassis
becoming "live" in the event of failure of the earth path between the
chassis.

Phil says that an earth continuity conductor should not also be a current
carrying conductor. Easier said than done in a case like this. If HT- is
connected to mains earth at the PSU, as would normally be the case, then it
is impossible to force HT current to flow through a designated HT- lead and
not through a separate earth lead.

David.