Product Manual
3. Installation 8-2018
30 A056K730 (Issue 4)Copyright © 2018 Cummins Inc.
3.2.1 AC Connections
RA Series transfer switches are supplied with screw type terminals for the Utility, Generator, Load, and
Neutral power connections. Either copper or aluminum cables can be used for AC connections.
Connect the Utility, Generator, Load, and Neutral conductors to the clearly marked terminals on the
transfer switch. Use a wire brush to remove any surface oxides from the cables. Verify that all connections
are correct before tightening the lugs. All lug connections must be tightened to the proper torque values
listed in the tables below.
Perform wiring in the following sequence:
1. Test the operation of the generator set from its own controls.
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. Stop the generator set and 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 line, load, and generator
directly to the transfer switch terminals or circuit breaker(s), which are marked A and B. A neutral bar
is standard on the switches. For wire sizes and torque specifications, see the tables below.
TABLE 3. SCREW TYPE TERMINALS AND TORQUE VALUES FOR EXTERNAL POWER GENERATION ON
NON-SERVICE ENTRANCE TRANSFER SWITCHES
Switch
Size
(Amps)
Terminal Description
Utility, Generator, and Load
Terminals
Neutral Bar Terminals Ground Terminals
Cables
per
Pole
Range of
Wire
Sizes
Tightening
Torque
No. of
Cables
Range of
Wire
Sizes
Tightening
Torque
No. of
Cables
Range of
Wire
Sizes
Tightening
Torque
100 Amp 1
#14 to 2/0
AWG
120 in-lb
(14 Nm)
3
#14 to 2/0
AWG
120 in-lb
(14 Nm)
2
#14 to 1/0
AWG
120 in-lb
(14 Nm)
200 Amp 1
#6 AWG
to 300
MCM
275 in-lb
(31 Nm)
3
#6 AWG
to 300
MCM
275 in-lb
(31 Nm)
2
#14 to 1/0
AWG
120 in-lb
(14 Nm)
400 Amp 1
3/0 AWG
to 600
MCM
275 in-lb
(31 Nm)
3
#3/0 AWG
to 600
MCM
275 in-lb
(31 Nm)
3
#6 to 3/0
AWG
120 in-lb
(14 Nm)