How to Wire a 3 Phase Air Compressor
How is an air compressor wired and where do the wires go? Wiring a 3 Phase Motor for an Air Compressor, The Basic Requirements for Wiring Electric Motors, 3 Phase Motor Circuits.
Air Compressor Electric Motor
Electrical Question: How is a 3 phase air compressor wired and where do the wires go?
- We have a Saylor Beall air compressor we are trying to get wired up.
- It ran fine at the previous shop and then we moved it to this shop.
- The motor is 3 phase and it appears to be wired according to the diagram for the low voltage 220.
- The label shows that it can be wired for 220 or 460. It is all wired and hooked up to the controller, but here is where we are having problems, we cant get it to start, it only hums.
- The motor starter is a Cutler Hammer # A10CNO. The wires from our shop circuit breaker has 2 yellow hot wires at 120 volts each, 1 white neutral wire and 1 green ground wire.
- Is it possible to wire the compressor with this combination of wires and where do they go?
- When the compressor was moved it was simply unplugged from the wall and moved, all pressure switches and motor wires are in their same locations as before.
This electrical wiring question came from Cody in Enid, Oklahoma.
Thanks for your electrical wiring question Cody.
Wiring a 3 Phase Motor for an Air Compressor
The Basic Requirements for Wiring Electric Motors
- Every motor should have a name plate which is typically attached on the side or end of the motor. The information found on the label tells all about the motor size and electrical requirements. To stay on track with this question, the shop where the motor is to be installed must have an electrical service which supplies either 3 phase 230 volts, or 3 phase 460 volts.
Electrical Service Panels
- Just like electric motors, an electrical service panel should be equipped with a label which is attached either on the cover or inside the door. The information on this label will be specific to the make and model of the electrical panel along with the voltage and amperage rating. Here in the USA, a typical home electrical panel may be 120/240 volts 125 amps. The actual amperage capacity of the panel is best known by examining the Main Disconnect or Main Circuit Breaker, which will have the amperage rating identified, such as on the breaker handle.
Electrical Power for 3 Phase Motors
- Without getting too technical, a 3 phase electrical service panel will produce 3 separate lines of electrical power. A 120/240 volt single phase panel found at a home or shop can only provide up to two separate lines of power, therefore this type of electrical service could not provide the necessary power for a 3 phase motor.
3 Phase Motor Starters and Control Circuits
- As described above, a typical 3 phase motor circuit will have 3 separate insulated wire conductors for the power and the ground wire. A neutral wire is not required for a 3 phase motor.
- Wiring Electrical Control Relays
- How to wire control relays for equipment such as Generators, Air Conditioners, Heating Furnace, and other high demand equipment. Full explanation describing the principles which are easily adapted to residential wiring applications.
More about Wiring Electrical Control Relays
A Summary of Wiring 3 Phase Motors
- Identify the required voltage and amperage.
- Determine if the electrical service panel has the same voltage and available amperage capacity.
- Electric motors are typically wired to a motor controller or motor starter which is sized appropriately to the horsepower of the motor and has thermal overload protection.
More about Electrical Circuit Wiring
House Wiring Circuits and Circuit Breakers
This article looks at common 120 volt and 240 volt house wiring circuits and the circuit breakers that are installed identifying the types and amperage sizes used in most homes.
Electrical Panel Circuit Listing
- Electrical Codes for Home Wiring
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More about Electrical Codes For Home Wiring
Home Electrical Circuit Breakers
Home Electrical Circuit Breakers
A guide to home electrical circuit breakers and how they work to protect your electrical wiring. When properly installed, your home electrical wiring is protected by a circuit protection device.
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Consult your Local Building Department about Permits and Inspections for all Electric Wiring Projects.
The Safest Way to Test Electrical Devices and Identify Electric Wires!The Non-Contact Electrical Tester
This is a testing tool that I have had in my personal electrical tool pouch for years, and is the first test tool I grab to help identify electrical wiring. It is a Non-contact tester that I use to easily Detect Voltage in Cables, Cords, Circuit Breakers, Lighting Fixtures, Switches, Outlets and Wires. Simply insert the end of the tester into an outlet, lamp socket, or hold the end of the tester against the wire you wish to test. Very handy and easy to use.
The Quickest Way to Check for Faulty Electrical Wiring!The Plug-In Outlet Tester
This is the first tool I grab to troubleshoot a problem with outlet circuit wiring. This popular tester is also used by most inspectors to test for power and check the polarity of circuit wiring.
It detects probable improper wiring conditions in standard 110-125 VAC outlets Provides 6 probable wiring conditions that are quick and easy to read for ultimate efficiency Lights indicate if wiring is correct and indicator light chart is included Tests standard 3-wire outlets UL Listed Light indicates if wiring is incorrect Very handy and easy to use.
Strip Off Wire Insulation without Nicking and Damaging the Electric Wire!The Wire Stripper and Wire Cutter
My absolute favorite wire stripping tool that I have had in my personal electrical tool pouch for years, and this is the tool I use to safely strip electrical wires.
This handy tool has multiple uses:
The wire gauges are shown on the side of the tool so you know which slot to use for stripping insulation.
The end of the tool can be used to grip and bend wire which is handy for attaching wire onto the screw terminals of switches and outlets..
The wire stripper will work on both solid and stranded wire. This tool is Very Handy and Easy to Use.
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We are using a 3 phase 240 volt system and hooking up to an air compressor.
We used a pressure switch by Square D part number 9013 FHG12MIX.
The black and blue wires from the 3 phase are connected to the pressure switch and then connected to the motor. The red wire from the 3 phase is only connected to the motor.
After 3 months the motor burnt out. I was wondering if the Red wire should be connected to the pressure switch and then connected to the motor, like the the black and blue wires?
When controlling a 3 phase motor it is important to identify the HP size of the motor, which will help to select the type of motor controls. Most motors draw a great deal of amperage when they first start, therefor the motor will need some type of overload protection which is typically provided by a Motor Starter. Typical motor starter applications include a control circuit which then activates the motor starter. A control circuit can be wired to a pressure switch which would activate the motor starter. In this case, the motor starter would have all of the 3 phase wires running through the starter.
To help you understand this with more detail I have placed additional information to this article which includes links to the motor control section where you will find more information and examples of typical wiring diagrams.
Thank you for sharing your question about wiring a 3 phase motor,
I have an air compressor I am currently trying to hook up and my old wiring is in conflict to the way the compressor I am installing was wired. I have changed the motor lead wires from 220 lv to 480 high voltage. The motor is 7 1/2 HP. I have a fused disconnect and motor starter. Please send link, thank you.
Please follow the link in the article which says: More about Wiring Electrical Control Relays. There you will see the wiring diagrams for motor control relays.
When changing the voltage of the motor be sure to see the wiring diagram on the motor label, and make sure of the circuit voltage which is supplied to the motor matches one of the optional voltage configurations of the motor.