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over ac circuit wire. When crossing station wire over
ac circuits is unavoidable, try to maintain a 3-foot
clearance.
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Use conduit for wiring runs whenever possible. Be
sure that the conduit is grounded. If the conduit is not
grounded, run a No. 12 wire from the conduit and
terminate it on the ac earth ground, or bond it to the
earth ground.
Run station wire on the baseboard or as close to the
floor as possible.
Run shielded wire for the stations that are having
interference problems. Ground the shield of the wire
and bond it to the ac ground.
Visually verify that the ac power line is grounded and
that it is bonded to the protector ground. Use an Ideal
circuit tester (or equivalent) or a VOM to verify that
the ac outlet is grounded. (See “AC Outlet Tests” on
page 2-7.) If the outlet is not grounded, run a No. 12
wire from either the grounding terminal or the center
screw of the ac outlet to the location where the ac
power line is earth grounded, and terminate it.
Install Built-in speakerphone stations (BIS-10, INS-22,
BIS-34).
Install a Z200A filter at the MERLIN II system station.
If interference is still present, install another Z200A
filter at the control unit.
If there is radio interference on the CO lines, use a
ZIOOA filter.
Change the ac outlet to a different branch circuit.
Move the control unit to a different location.
System Grounding Requirements 2-11