VTI UDS MB and FD Series - Manual (Page 4)

The minimum size wire is listed in the table below:
Verify the feeder insulation by Hy-potting each feeder between phase and ground with
voltage set to (2 x rated voltage + 1000V), e.g., 2000 VAC for 400/415 & 480V rating,
and 2500 VAC for 600V rating. If the Hy-pot test is successful, proceed to connect the
ground wire in the feeder cable to the ground lug at the feeder supply point. Now proceed
to connect each of the three phase conductors in the feeder cable circuit breaker or
disconnect switch in the feeder supply point.
Close the transformer compartment door. Also close the optional primary disconnect
switch door if applicable.
Ensure that the primary and secondary disconnect switches and the 42 circuit breakers on
the UDS cabinet are all in the “OFF” position.
This completes the installation of the Unitized Distribution Substation.
4. Operation
Provide power to the UDS by closing the disconnect switch on the circuit breaker feeding
the UDS.
If supplied as an option, place the primary disconnect switch or the primary circuit breaker
to the “ON” position.
Place the secondary disconnect switch or breaker to the “ON” position.
Place the individual circuit breaker to the “ON” position, as desired.
C a b l e S i z e
400/415V transformer rating Minimum wire size AWG
30 KVA 8 AWG
45 KVA 6 AWG
75 KVA
480v transformer rating
30 KVA
45 KVA
75 KVA
2 AWG
Minimum wire size AWG
8 AWG
6 AWG
2 AWG