[TenTec] TT 940 Power Supply

[Stuart Rohre]

As a follow up to Bob's comment about checking for continuity between 
safety ground terminal on an outlet and neutral; it is my understanding 
from current codes, written up in electrical trade magazines 
discussions; that the neutral is bonded at one place to the safety 
(green) ground wire, and that is at the breaker box, presumably at the 
entry to the facility.

Bonding in the UPS box seems counter to this practice, and certainly 
creates a loop between neutral and safety ground.

Often in practice we have found in our lab facility,  multiple loops 
caused by bonding green safety ground to neutral in multiple boxes that 
may exist between the service entry and the ultimate site of the powered 
instrument.  It caused bad noise problems such that I finally had a 
special feed conduit installed that was bonded at its source of power 
but was insulated on brackets until it reached the lab needing low noise 
A/D wiring.  That finally met our noise spec.  There was still 
continuity from neutral to safety ground, but we controlled where that 
singular bond was made.

-Stuart
K5KVH