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Section 7 - Wiring
7.1 Wiring Instructions
- Wiring should be in accordance with the national electrical code and any local codes or
regulations. Have a licensed and competent electrician ensure that the voltage supplied
matches the compressor voltage.
- Inadequate wiring size can cause insufficient voltage at the compressor during start-up.
Overheating and damage can result to the motor and controls.
- Failure to use the pressure switch may result in overpressure of the compressor or other
components in the system. Overpressure of the compressor can result in blown head
gaskets or other damage.
- Grounding Instructions: This product must be connected to a grounded, metallic,
permanent wiring system, or an equipment grounding terminal or lead on the product.
The supply wire must be of adequate size and no other equipment should be
connected to the same line. The adjacent table lists the recommended wire
size for each model based on a 100’ run and lowest operating voltage.
Consult factory for longer runs. The motors supplied are multiple voltage
motors. A label on the pressure switch cover indicates the voltage the motor
is pre-wired for. If the supply voltage, on site, is different from the voltage
indicated on this label, change the internal motor voltage connections to
match the supply voltage. To change internal voltage connections, remove
the cover plate located on the rear or side of the motor and reconnect the
wire leads as shown on the motor’s wiring diagram.
On all three phase compressors an arrow on the motor indicates the required
direction of rotation of the compressor. If the compressor rotates in the
opposite direction, reverse the rotation of the motor. Interchanging any two
incoming supply wires reverses rotation of three phase motors.
- Single-phase motors include internal thermal overload protection, which has an
automatic reset device.
- Disconnect electrical power before servicing to disable reset devices. Thermal protection
can automatically start the motor when the protector resets.
On single phase models, the motor is pre-wired to the pressure switch provided, which controls starting (cut in pressure) and
stopping (cut out pressure) of the motor. The pressure switch is factory set. Standard models switch is set at 27 to 30 psig cut
in and 40 to 44 psig cut out. Low pressure models ("-LP") switch is set at 13 psig cut in and 18 psig cut out. Consult General
Air Products before adjusting the pressure switch.
On three-phase compressors, the motor is not pre-wired to the pressure switch. Refer to the three phase wiring instruction
drawing for recommended wiring. A motor starter is required, for all three phase models, to protect the motor from
overload conditions to meet NEC, NFPA70, Article 430. A motor starter is recommended, for all single phase models.
Consult the National Electric Code and local codes for motor starter requirements. Refer to the proper wiring instruction drawing
for recommended wiring to a starter.
- Do not run two phases of a three phase supply through the pressure switch. Serious
damage can result. Warranty is voided if connected this way.
Minimum Recommended Wire Size
Model # 1 Phase 3 Phase
OL(T)12516** 12 N/A
OL(T)25033** 12 N/A
OL(T)36550** 12 12
OL(T)43075** 10 12
OL(T)615100** 6 12
OL(T)915150** 6 12
OL(T)1225200** 10 10
OL(T)32016**-LP 12 N/A
OL(T)55033**-LP 12 N/A
OL(T)86050**-LP 12 12
OL(T)99075**-LP 10 12
