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

Electrical Technology

Manual and Automatic Transfer and Changeover 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 and main panel 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. The wiring diagrams show both the 120V/240V NEC and 230V/400V IEC system voltages (single phase and three phase supply) for manual and auto transfer and changeover switches. Now let’s begin as follows.

The following fig-1 shows the different 1-Phase and 3-Phase connections for manual and automatic changeover and transfer switches. Lets explain one by one in detail as follows.

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How to Wire Single Phase Manual Transfer / Changeover Switch?

Wiring 230V, 1-Phase Changeover Switch – IEC

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 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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Wiring 120V & 240, 1-Phase Manual Transfer Switch – NEC

The following wiring diagram in fig-3 shows the Reliance manual transfer switch connected to the main 120/240 V panel and a portable generator. Step by step guide is posted before in the post under the title Wiring a Portable Generator Using Manual Transfer Switch for 120 & 240V.

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The related wiring diagram in fig-4 shows the 2 pole manual transfer switch (GE TC10323R / GE TC35322) connected to the main 120/240 V panel and a portable generator to 240V subpanel installed for emergency power. Step by step guide is posted before in the post under the title Wiring a Generator Using Manual Transfer Switch for 240V.

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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-5, the backup power of batteries is connected to the main distribution board through 2-Pole, single phase automatic changeover or transfer switch (ATS) and UPS / Inverter.

The working and operation of this circuit is the same as above except the automatic changeover switch (ATS) will detect the utility power when restored 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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How to Wire Three Phase Manual Changeover/Transfer Switch

Fig-6 shows how to wire a four pole, three phase manual changeover switch to the main distribution board. This is the same connection as we discussed above for single phase wiring except that there are three phase wires instead of line and neutral.

The three phase utility power (L₁, L₂, L₃ & N) are directly connected to the upper side of the manual changeover switch, while the backup power of the three phase generator is connected to the first four (right) slots of the 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 to the “Generator Supply” when main power is not available and then back to the “Main Power” when utility power is restored.

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How to Install a Three Phase Automatic Transfer/Changeover Switch

Fig-7 shows 4-Poles, 3-Phase automatic transfer switch (ATS) connection to the main distribution board. All the wiring connections are the 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 a Generator using ATS / Changeover Switch

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

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

In our another wiring tutorial, we have discussed in detail about How to do Manual & Auto UPS / Inverter Wiring using Changeover / ATS Switch?. You will be able to know how to connect UPS / Inverters and batteries to the home supply with the help of two poles, 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?

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

Wiring Color Code (IEC & NEC):

We have used the IEC and IEC wiring color codes for 230V/400V and 120V/240V circuits. You may use the local area codes or i IEC – International Electrotechnical Commission (UK, EU etc.) or NEC (National Electrical Code [US & Canada] where;

NEC:

Single Phase 120V AC:

Black = Hot or Line
White = Neutral
Green / Yellow or bare conductor = Ground Wire

Single Phase 240V AC:

Black = Hot 1 or Line 1
Red = Hot 2 or Line 2
White = Neutral
Green / Yellow or bare conductor = Ground Wire

Three Phase 208 AC:

Black = Hot 1 or Line 1
Red = Hot 2 or Line 2
Blue = Hot 3 or Line 3
White or Gray = Neutral
Green / Yellow or bare conductor = Ground Wire

Three Phase 240 AC (High Leg Delta):

Blue = Hot 1 or Line 1
Orange = Hot 2 or Line 2 (HIGH LEG DELTA)
Black = Hot 3 or Line 3
White or Gray = Neutral
Green / Yellow or bare conductor = Ground Wire

Three Phase 480V & 600V AC

Brown = Hot 1 or Line 1
Orange = Hot 2 or Line 2
Yellow = Hot 3 or Line 3
White or Gray = Neutral
Green / Yellow or bare conductor = Ground Wire

IEC:

Single Phase 230V AC:

Brown = Phase or Line
Blue = Neutral
Green / Yellow = Earth Conductor = Earth Conductor

Three Phase 400V – 415V AC:

Brown = Phase 1 or Line 1
Black = Phase 2 or Line 2
Grey = Phase 3 or Line 3
Blue = Neutral
Green / Yellow = Earth Conductor

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General Precaution

General Precautions while playing with Electricity.

Disconnect the main power source (by switching OFF the main switch in the distribution board / consumer unit and load center / main panel) before servicing, repairing or installing electrical equipment.
Never try to work on electricity without proper guidance and care.
Troubleshooting, repairing, installation and modification work related to electricity can be done only in presence of those persons who have good knowledge and practical work and experience who know how to deal with electricity.
Read all the instructions, user manuals, cautions, local area codes 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.
Use the suitable voltage and ampere rating of the switch with appropriate wire size and proper size MCB according to the load rating.
Switch off the main MCB circuit breaker to make sure the power supply is OFF before wiring an existing or new outlet or switch with an electrical/junction box.
Contact the authorized and licensed electrician for switch installation if you are not sure about the wiring diagrams.
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 the 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 or portable generator using changeover and ATS switches, please leave a comment in the comment box below and we will be there to assist you more in details.

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