Product Manual

3. Installation7-2019
15A052S254 (Issue 3) Copyright © 2019 Cummins Inc.
When installing conduit, observe the following precautions:
• The RA Series transfer switch includes multiple knockouts in the cabinet for ease of wiring. If you
decide to drill your own holes instead of using the knockouts provided, cover the transfer
switch and both terminal blocks to prevent accidental entry of metal chips before beginning
conduit installation.
• If using rigid conduit between the generator set and the transfer switch, install at least 2 feet (610
mm) of flexible conduit between the rigid conduit and generator set to absorb vibration.
• Control circuit wiring may be run through separate conduit (for the C13N6H-C20N6H products,
Cummins recommends single conduit). Cutouts are available through the bottom of the cabinet.
Refer to the transfer switch product image shown in Appendix A on page 31.
NOTICE
Running control circuit wiring and AC wiring in the same conduit is allowed with certain
conditions per the NEC code (unless prohibited by the authority having jurisdiction).
Cummins recommends shielded wire be used where AC and DC wiring is run through a
single conduit.
3.3.1 AC Connections
RA Series transfer switches are supplied with screw type terminals for utility, generator set, and neutral
power connections. Either copper or aluminum conductors can be used for AC connections. Load
connections are directly to the individual branch breakers (not supplied with the automatic transfer switch).
Use only directly connected Square D Type QO for the branch circuit breakers.
Connect the utility, generator set, and neutral conductors to the clearly marked terminals in the cabinet.
Verify that all connections are correct before tightening the lugs. Connect utility and generator set neutral
wires to the lugs on the circuit breaker backplane Neutral bus. All lug connections must be tightened to the
proper torque values listed in the tables below.
Perform wiring in the following sequence:
Stop the generator set and remove the negative lead from the cranking battery to prevent starting.
1. Stop the generator set.
WARNING
Failure to prevent the generator set from starting before wiring procedures are performed
presents a shock hazard that can cause severe personal injury or death. Disconnect
generator set battery, negative (-) terminal first, before proceeding.
2. Remove the negative lead from the cranking battery to prevent starting.
WARNING
AC voltages and currents present an electrical shock hazard that can cause severe personal
injury or death. Make sure that both AC power sources are disconnected.
3. Make sure that both AC power sources are disconnected.
4. Connect power cables of sufficient size to carry rated current from the utility, and generator set
directly to TB5 terminal blocks, which are marked Utility and Generator Set. A neutral bar is located
on the RA112L1 Automatic Transfer Switch interior. For wire sizes and torque specifications, see
the table below.