7. ELECTRICAL INSTALLATION

Fan Disconnect

A disconnect for the fan needs to be sized to handle the recommended fusetron size. Example: For a 24" fan the first chart on Page 17 would be used, and the fusetron size is 30 AMP. Install the fusetron recommended in the disconnect. A circuit breaker can be used, however, the circuit breaker or any fuse used must be a time delay type to allow the initial starting inrush current to the fan.

Conductor Size for the Fan Disconnect to Fan Wiring

The conductor size for the fan needs to be sized according to the distance between the fan and disconnect. Example: For a 24" fan located 200' from the disconnect use the first chart

on Page 17 to determine the conductor size to be a 14 AWG. The proper size wiring must be used to make sure a voltage drop does not occur.

Fan Motor Controller

Size the fan motor controller according to the motor ratings for a convenient control location as follows:

Motors with internal overload protection will require a magnetic contactor to control fan operation. Motors without overload protection will require a magnetic starter with overload protection to control fan operation.

Single Phase

A 3-wire system should be provided for fans to be operated on single phase power. The three wires consist of the two current conductors and a ground. The current carrying conductors are wired per the diagram on the motor. The ground is secured to the motor frame. On 2 HP explosion proof motors thermostat wires are provided with the motor, and must be connected to the fan motor magnetic controls.

Three Phase

A 4-wire system should be provided for fans to be operated on three phase power. The four wires consist of three current carrying conductors, and a ground. The current carrying conductors are wired per the diagram on the motor. The ground is secured to the motor frame. On 2 HP explosion proof motors thermostat wires are provided with the motor, and must be connected to the fan motor magnetic controls.

When installing electrical service for explosion proof motors make sure all conduit and connectors exposed to the conditions of the motor are rated for the Class II group F and G location of the motor.

Installation Check

When the fan is completely assembled and wired the unit needs to be checked for proper rotation. Provide power to the fan controls and start the fan momentarily. Make sure the fan blade rotates to exhaust air from the bin. If the blade is rotating the wrong direction, have your electrician correct as follows:

Single Phase System

With the power OFF at the fan disconnect, the motor lead wires at the fan motor need to change as indicated on the motor to reverse the blade rotation. The unit then needs to be rechecked for proper rotation.

PNEG-524 Roof Exhaust Fan

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