Trane BCI-I Integration Manual page 17

BCI IntelliPak Rotary Switches and LEDs
Ground Measurements
General Information and Checkout Procedure
Method 1:
AC voltage between shield conductors and device chassis ground-
the voltage difference between BACnet MS/TP device chassis ground
connections should be close to zero. If the voltage difference is greater that
4.0 Vac, there will be marginal communication or intermittent
communication problems. If the voltage difference is greater that 7.0 Vac,
some devices will no longer communicate.
Method 2:
AC voltage between earth ground and device chassis ground- the
chassis ground of the UC400 needs to be connected to earth ground by
some route.
Note: Do not assume that the building frame is a valid earth ground.
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Measurement Expected Value
Measure AC current Vac ≤ 2.0 V
across the current
termination and confirm
that only one end of the
shield conductor is tied to
the earth ground
Measure AC current Vac ≤ 4.0 V
across the current
(Must comply with National Electrical
termination and confirm
Code™and local electrical codes)
that only one end of the
shield conductor is tied to
the earth ground
ACC-SVP01B-EN • BCI-I Integration Guide