Honeywell W7620 - Manual (Page 12)

2. To disable a controller, remove both legs of I
or removing connections from Terminals TR
and TR earth-ground.
the AC power. Removing only one leg may
prevent other controllers on the same
transformer from communicating on the
CNAP network.
I
L
The W7620 Zone Control System must be earth-grounded
at each cluster of W7620 controllers (one or mote W7620
controllers powered by a single 24 Vac transformer). Use
No. 18 AWG or larger copper conductor run to a known
earth-ground, such as a water pipe driven into the earth
or the ground connection found within the power
distribution panel. The power distribution panel must be
earth-grounded per National Electric Codes. Do not “se
the ductwork or the wiring conduit since these do not
necessarily provide a good ground. The following
provides grounding details:
1. Earth-ground one W7620 within a group of
W7620s connected to a given transformer.
Connect the ground wire to the green ground
screw on the W7620 chassis. See Figure 7.
connect the same side of the
transformer secondary to the same terminal
number on each W7620.
2. Grounded Transformer Secondaries: If the
Transformer has a grounded secondary, it is
necessary to identify the grounded side. Use an
ohm meter to test for conductivity between one
side of the transformer and the suspected
grounding plane (usually the controller chassis).
If one side of the transformer is grounded,
connect the grounded secondary to the
earth-ground connection on the W7620 (TR
earth-ground).
to connect grounded secondary to
will cause damage to the
Tie each W7620 (using ground
screw) together in the cluster.
Earth-ground each cluster at some
accessible point that is a good
distribution ground.