 |
Personal injury or death can result from high voltage. Make sure the power source is disconnected. Lock out the disconnect switches and tag the switches "DO NOT OPERATE". |
Caterpillar transfer switches are supplied with solderless screw type terminals. The terminals are standard for the normal power connection, the emergency power connection, and the Load. Table 1 lists the number of cable lugs and the sizes of cable lugs that are supplied for each ampere rating.
Connect the conductors for normal power to the normal power terminals on the transfer switch. Connect the conductors for emergency power to the emergency power terminals on the transfer switch. Then, connect the conductors for the load to the load terminals on the transfer switch. Remove any surface oxides from the cables by cleaning the cables with a wire brush. Verify that all the connections are correct before tightening the lugs. All of the cable lugs must be tightened to the proper torque values. The proper torque values are shown in table 2.
Note: Do not route cables or wiring behind transfer switches that have the connections in the front of the switch.
If the connections for the power sources are made to a bus bar in the rear of the cabinet, the following items must be used: compression washer, a flat washer and a minimum of a grade five bolt. The bolt must be torqued to the corresponding value in table 3.
| Screw Terminals for External Power Connections | ||||
|---|---|---|---|---|
| Switch Size in Amp. | Normal, Emergency, and Load Terminals | Neutral Bar (1) | ||
| Cable Per Pole | Range of Wire Sizes | No. of Cables | Range of Wire Sizes | |
| 40 | 1 | #8 to 1/0 AWG | 3 | #8 to 1/0 AWG |
| 80 | 1 | #8 to 1/0 AWG | 3 | #8 to 1/0 AWG |
| 100 | 1 | #8 to 1/0 AWG | 3 | #8 to 1/0 AWG |
| 150 | 1 | #8 to 3/0 AWG | 3 | #8 AWG to 300 MCM |
| 200 | 1 | #8 to 3/0 AWG | 3 | #8 AWG to 300 MCM |
| 225, 250 (2) | 1 | #6 AWG to 250 MCM | 3 | #6 AWG to 300 MCM |
| 260, 300 (2), 400 | 1 | #4 AWG to 600 MCM | 3 | #4 AWG to 300 MCM |
| 600 | 2 | #2 AWG to 600 MCM | 8 | #2 AWG to 600 MCM |
| 800 1000 1200 |
4 | #2 AWG to 600 MCM | 12 | #2 AWG to 600 MCM |
| 1600 2000 3000 4000 |
All of the terminals are located in the rear of the switch and the terminals are arranged for bus bar connections. | |||
| ( 1 ) | A Neutral Bar is not always required. |
| ( 2 ) | IEC Ratings Only |
| Tightening Torque for Lugs | ||
|---|---|---|
| Socket Size Across Flats | Torque | |
| N·m (lb in) | lb ft | |
| 1/8 | 5.1 (45) |
4 |
| 5/32 | 11.3 (100) |
8 |
| 3/16 | 13.6 (120) |
10 |
| 7/32 | 16.9 (150) |
12 |
| 1/4 | 22.6 (200) |
17 |
| 5/16 | 31.1 (275) |
23 |
| 3/8 | 42.4 (375) |
31 |
| 1/2 | 56.5 (500) |
42 |
| 9/16 | 67.8 (600) |
50 |
| Tightening Torque for Bus Bars | ||
|---|---|---|
| Bolt Size | Bolt Torque (Grade 5) | |
| N·m (lb in) | lb ft | |
| 1/4-20 | 8.1 (72) |
6 |
| 5/16-18 | 14.9 (132) |
11 |
| 3/8-16 | 33.9 (300) |
25 |
| 1/2-13 | 81.3 (720) |
60 |