How to Wire Auto & Manual Changeover & Transfer Switch – (1 & 3 Phase)

Manual and Automatic Changeover / Transfer Switch Wiring & Connection

In our step by step electrical wiring installation tutorials series, We will show how to wire and connect single phase and three phase automatic and manual changeover and transfer switches to the home distribution board to use the backup power supply such us batteries power with UPS and inverters or generator power in case of emergency breakdown and power outage. Now let’s begin as follow.

The following fig 1 shows different single phase and three phase connections for manual and automatic changeover and transfer switches. Lets explain one by one in detail as follow.

Click image to enlarge

How to Wire Single Phase Manual Transfer / Changeover Switch 

In fig 2, different connection and wiring diagrams are shown for a two pole, single phase manual changeover switch. The upper portion of the changeover switch is directly connected to the main power supply while the lower first and right connections slots are connected to the backup power supply like generator or inverter. The left side of lower slots are connected to the main board as load.

In case of power failure, the manual changeover switch can be changed to to the generator / inverter position. This way, power supply will continue to the load points through the inverter or generator. When power supply restores from the power house, simply switch back the changeover switch position to the “Main Power Supply”.

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How to Connect Single Phase Automatic Changeover / Transfer Switch (ATS)  

If you are tired of manual operation of changeover switches, ATS is the best alternative to use then. In the following fig 3, the backup power of batteries is connected to main distribution board through 2-Pole, single phase automatic changeover or transfer switch (ATS) and UPS / Inverter.

The working and operation of this circuit as same as above expect the automatic changeover switch (ATS) will detect the utility power when restores from the power house and automatically transfer from the Generator / Inverter to the Main Power supply. In case when utility power is not available, the ATS will transfer the switching position to the Inverter, hence electrical appliances will be still in operation mode without interruption through the stored power in the batteries.

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• Three Phase Electrical Wiring Installation in Home – NEC &  IEC
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How to Wire Three Phase Manual Changeover/Transfer Switch 

Fig 4 shows that how to wire a four poles, three phase manual changeover switch to the main distribution board. This is the same connection as we discussed above for single phase wiring expect that there are three phase wires instead of line and neutral.

The three phase utility power as (L₁, L₂, L₃ & N) are directly connected to the upper side of manual changeover switch, while the backup power of three phase generator is connected to the first four (right) slots of at lower side. The left side four slots connection points are connected to the load then.

Since the operation is manual, You have to change the changeover lever to the appropriate position manually to restore the power i.e. Change the lever position the “Generator Supply” when main power is not available and then back to the “Main Power” when utility power restores.

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How to Install Three Phase Automatic Transfer/Changeover Switch 

Fig 5 shows 4-Poles, 3-Phase automatic transfer switch (ATS) connection to the main distribution board. All the wiring connections are same as above for manual operation of three phase changeover switch but the switching operation is automatic.

In case of emergency breakdown, the automatic transfer switch will automatically divert the switching position to the “Generator Supply” and when the main supply restores, it will transfer the power flow to the “Utility Power” when using emergency generator set for backup power..

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How to Connect Generator with ATS / Changeover Switch 

In our previous post, we have shown in very details that how to connect a portable generator to the home supply with automatic and manual transfer switches. It is also shows the working and operation for different changeover switches wiring connections like, single phase manual changeover switch with generator, three phase manual transfer switch connection with generator as well as single phase and three phase automatic transfer switches connections to the 1 and 3 phase generators and main fuse board.

How to Wire UPS / Inverter with Transfer Switch / Changeover Switch 

In our another wiring tutorial, we have discussed in details about How to do Manual & Auto UPS / Inverter Wiring with Changeover / ATS Switch?. You will be able to know how to connected a UPS / Inverters and batteries to the home supply with the help of two pole, single phase automatic and manual changeover / Transfer switch in case of partial load and full load as well as how the system works at all?

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Wiring Color Code (IEC & NEC):

We have used Red for Live or Phase , Black for Neutral and Green for Earth Wire. You may use the specific area codes i.e. IEC – International Electrotechnical Commission (UK, EU etc) or NEC (National Electrical Code [US & Canada] where;

NEC:

Single Phase 120V AC:

Black = Phase or Line, White = Neutral and Green/Yellow = Earth Conductor

Three Phase 208 AC:

Black = Phase ₁ or Line1, Red = Line ₂, Blue = Line ₃, White / Gray = Neutral and Green/Yellow = Earth Conductor

IEC:

Single Phase 230V AC:

Brown = Phase or Line, Blue = Neutral and Green = Earth Conductor

Three Phase 208 AC:

Grey= Phase ₁ or Line1, Black = Line ₂, Brown = Line ₃, Blue = Neutral and Green = Earth Conducto

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Note: Use 6 AWG (7/064″ or 16mm²) cable and wire size to connect the UPS to the main panel board.

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General Precautions

• Disconnect the power source before servicing, repairing or installing electrical equipments.
• Use the proper cable in size with this simple calculation method (How to determine the suitable size of cable for Electrical Wiring Installation)
• Never try to work on electricity without proper guidance and care.
• Work with electricity only in presence of those persons who has good knowledge and practical work and experience who know how to deal with electricity.
• Read all the instructions, user manuals, cautions and follow them strictly.
• Doing your own electrical work is dangerous as well as illegal in some areas.Contact the licensed electrician or the power supply company before practicing any change in electrical wiring connection.
• The author will not be liable for any losses, injuries, or damages from the display or use of this information or if you try any circuit in wrong format. So please! Be careful because it’s all about electricity and electricity is too dangerous.

If you are still facing difficulties to wire the UPS and batteries with changeover and ATS switches,, please leave a comment in the below comment box and I will be there to assist you more in details.

You may also read other Electrical Wiring Installation Tutorials.

• How to Wire Wire a Distribution Board [Single Phase]?
• How to Wire a Distribution Board with RCD – Single Phase ?
• Three Phase Electrical Wiring Installation in Home – NEC &  IEC
• Three Phase Electrical Wiring Installation in a Multi-Story Building