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How to Connect Automatic UPS / Inverter to the Home Supply System?

Automatic Inverter / UPS System Connection & Wiring Circuit Diagram

Introduction to Automatic Inverter / UPS Wiring

Power failure and emergency breakdown may happen any time due to short circuit, damage to electric transmission lines, substations or other parts of the distribution system , storms and other bad weather conditions etc. In this case, emergency generator or battery backup can be used to restored the electric power to the home and other connected appliances. In some case, it is very important to restore the power as soon as possible like in Hospital ICU, military, Intelligence and security systems & offices etc. This is where we use the generator and Inverter / UPS (Uninterruptible Power Supply) system with the help of backup batteries and inverter.

For this purpose, we have to shows an automatic UPS / Inverter system connection and wiring to the home or office supply. We have different tutorials on UPS and Inverters wiring & installations to the home distribution boards such as manual, automatic and inverter / UPS with changeover switches.

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Why & Where we Need Auto UPS / Inverter System?

As we have mentioned above that emergency breakdown and power blackout may happen anytime due to a number of reason. In some cases, you may need a continues and uninterruptible power supply to the connected system such as security networks & systems, operation theater & ICU in hospitals, airports, military and intelligence systems and other important electrical networks. In other ordinary cases where you face load-shedding from the power supplier, unavailability of secondary power i.e. generator, solar, wind power etc, low voltages issues, shortage of stored power in the batteries, where you need an uninterruptible power to your home, office, PC, or particular rooms and load points in home or office in case of failure of main power supply. In all those situations,  you need an automatic UPS / Inverter wiring connection to the home panel board.

How to Connect a UPS / Inverter to the Home Supply System?

To connect an inverter / UPS to the home electric supply system, follow the steps below:

First of all, disconnect those Live (Line) wires of two circuit breakers from the main distribution board which are connected to the main double pole switch of those particular rooms (As shown in Fig) which you want to connect to the automatic supply (in both cases from battery and main utility power without any interruption).

Suppose, you need to connect only two rooms and their load with UPS automatic system as shown in fig . You will have to disconnect the live wires of these rooms from the main power supply distribution board. Now connect these two live wires (of those specific room which have to be connected to the UPS System) to the output of UPS through the two single pole MCBs (separated from the main panel board). Done.

Keep in mind that only the two connected MCBs (and their related and connected load) to the inverter will supply continues power in case of blackout. To charge the Battery via inverter, connect the Inverter / UPS to the outgoing of main double pole (DP) MCB through a 3 Pin Power Plug and 3 Pin Power socket to the main supply.

Note: To be in safe mode, use 6 AWG (7/064″ or 16mm2) cable and wire size to connect the UPS to the main panel board.

Below is a given UPS  Inverter connection and wiring diagram to the home supply. The circuit shows that only two rooms of the home are depends on the UPS and Batteries as well as main supply to maintain the uninterruptible power to the connected appliances and load such as lighting points and fans etc and the other loads are fed up by utility power only. Once you get the basic idea of UPS connection, proceed to know how it works in both cases i.e. operation of the circuit when utility power is available and battery backup as secondary power in case of power failure.

You may also read:

Click image to enlarge

How to Connect a UPS - Inverter in Home Wiring
How to Connect a UPS / Inverter in a Home Wiring ?

Working Principle & Operation of Automatic UPS / Inverter

1. In case, when the utility power supply is not available:

In case of unavailability of main electric supply, power flow will continue to the particular rooms / office and appliances connected to the UPS system and battery where inverter convert the 12V DC system to Single Phase 230V AC (UK & EU) or 120V AC (US & Canada) voltages according to the specification and ratings.

Related Tutorials:

The Blue Line shows the power flow in the circuit from battery, UPS and then load points.

Click image to enlarge

Automatic UPS Inverter system connection and wiring diagram
UPS / Inverter Wiring & Connection Diagram

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2. In case, when power supply restores from the power house:

In this case, the main electric lines supplies power to the home appliances in particular connected rooms. Keep in mind that UPS / Inverter will start to charge the battery i.e. it will convert the main Single Phase 230V AC (UK & EU) or 120V AC (US & Canada) voltages into 12V DC to charge the battery for backup storage.

The Blue Line show the power flow from main distribution board to UPS/Inverter and then load points connected through UPS System.

Click image to enlarge

Automatic Inverter UPS Wiring to the Distribution Board
How to wire an inverter to your house?

Wiring Color Code:

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


Single Phase 120V AC:

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


Single Phase 230V AC:

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

General Precautions while playing with Electricity.

  • 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..

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You may also read other Electrical Wiring Installation Tutorials.

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    1. I was doing this in the early 90’s using computer UPS, it ran several lights, small television, and a fan. I used Jumper cables to supply 12VDC from my Vehicle, and left the car running til the power came back on

  1. Hi,<br /><br />UPS input and output neutral is shot circuited? Is this ok<br />If UPS for one room and generator for other room is connected … Still can we connect UPS outout neutral wire to mains ?<br /><br />thanks

    1. ♦ its not short circuited…, when Phase touch neutral without load then Short circuit occurs. <br />♦ refer to the other diagrams for this purpose under the &quot; Electrical Wiring&quot;,→UPS Wiring diagrams.

  2. For 5 fans and 5 lamps( energy saver) 1000 watts UPS with 2 batteries of 180 Amp/Hr is good, its have better efeicency. ok

  3. Seems to me like there isn&#39;t enough protection from the main switch to the UPS in case of a short circuit in this area.

  4. Hello Wasim Khan..first of all a very big thanks to you…<br /><br />Your description with the diagram is just very very simple to understand…<br /><br />But I have a few queries which I want to ask you. If you describe and simplify my these queries then I am going to install an inverter in my home as installing an inverter is very urgent in my room.<br /><br />My queries are simple. They are:

    1. Please give me the right solution sir..<br /><br />I am waiting to hear from you. Please give me the right solution so that I can install an Inverter for my room. Its urgent.<br /><br />Thanks.

    2. <br />eDon&#39;t worry…I am using the same wiring diagram, that why i suggested to you… <br />The working of these diagrams ar:<br />When main supply available… your all appliances will work on Main will as, it will charge your battery..<br />When main supply not available… Only those appliances will work which you have been connected to Inverter (UPS)…<br />Thanks

  5. I have read all your automatic ups wiring post.<br /><br />I am clearing my doubts again…this time not in complicated way.. :)<br /><br />I want to connect some of my electrical equipments of my house with Inverter. When main power house supply is available then all electrical equipments as well as those inverter connected equipments should also work over main power supply (not from battery).

    1. Thank you very much Sir… :)<br /><br />I&#39;ll do what you have told me to do. I think I have figured it out on which way should I follow as per your diagrams. Your posts helped me a lot.<br /><br />And I want to say thanks again and I will reply you again as soon as I successfully complete the wiring and installation of the inverter.<br /><br />Take care.

  6. Dear Sir, do we have to connect Neutral from the output plug of the UPS? Because you said in your previous diagrams that there is no need to connect a neutral wire since it is assumed to be already connected to the mains electricity? Thanks. It&#39;s a bit of a contradiction from the previous diagram!

  7. My question, is really on why is important to connect the neutral wire from UPS (Output) to main neutral link? Wouldn&#39;t it short-circuit?<br />

  8. Plus one more question from the phase output of the UPS instead of fuse can we use an MCB aka circuit breaker to help keep the circuit safe? Because the problem of the fuse is that if it breaks finding a replacement is hard so can we use an MCB switch instead of the fuse?

    1. Yes Wasim sir, I have the same query too like Azaan Kaul that can I connect a MCB instead of a fuse at UPS phase output? and if so then what would be the MCB Ampere? should I connect 10 Amp MCB? Please sir, reply this too… :)

  9. Hello Wasim Sir, this is Sudipto once again.. Today, I have bought Luminous Ion Sine Wave Inverter 1500 VA as per my required Load. Now, I have a query… On the back panel of the UPS, it is printed 24V DC. Thats where my confusion comes in my mind. Earlier, I decided to buy 12V 200Ah Exide Tall Tubular IT750 battery. But, that is 12V battery and now when today I bought the UPS, I saw there is

  10. Wasim sir, I have figure it out what I asked yesterday at night, that the UPS System works on 24V DC Supply when main line goes off. So, I think I have to connect two 12V Batteries in series and hence the battery bank should be connected to UPS so that the Voltage will be 24V but Ah of the battery bank will remain same. So, I decided to buy Two Exide IT400 Batteries (12V, 115Ah both).<br /><br />

  11. Wasim Sir, I have finally bought two Exide IT500 (150Ah). All materials are ready to install. I am going to do the wiring process tomorrow. But I have one confusion before doing wiring. Please reply it urgently sir. Its my painful request to you.<br /><br />My confusion is should I connect the UPS output neutral to main supply neutral wires directly? In the diagram, I can see that you have

    1. Sudipto Sinha.. Sorry and again sorry from the core of my heart for too late reply and response…!!!<br /><br /> Now… I read all your comments and Queries… your setting and system is good and proper… ( two 12 V batteries (in Series) for 24V system) .. <br /><br />Just Conect the Neutral wire (Output of UPS) to the main Neutral Link/Wire in your Distribution Board….

    2. thank you very much Wasim Sir. I have just read your reply and I&#39;ll connect the UPS Output Neutral to the main supply neutral wire coming from Main switch. <br /><br />I am doing the wiring today. :) I&#39;ll definitely reply you if all works fine. I know it will work as you described here.<br /><br />Once again thanks for your reply.

    3. Thank you so much for appreciation…. If you face any problem, then please reply… it would be great for us if we help you…

  12. hello Wasim Sir, after two days of wiring my house, I have completed the whole house wiring today. And its working!!!! Thanks a lot Sir. Everything is working perfect as it should. :)<br /><br />Oh, I just did one thing what I want to tell you. That is, I connected a 10Amp MCB at UPS Output phase line instead of Fuse what you described here, as MCB is more reliable than fuse and I can easily

    1. Dear Sudipto Sinha, <br />I really appreciate your successful (Practical) work and It restored my energy ;)<br />I am sure that your these kind of steps are Guarantor of your bright future in Electrical Engineering… Go On and best wishes,,,, <br />If you face any problem in future (God forbid)..Then we are here (Hod willing) to help you :)

  13. What is a neutral link? As per my understanding, it comprises of mainly neutral wires for each subcircuit and the main neutral wire if I am right? Please correct me if I&#39;m wrong. <br />Sir in the neutral link, there are many sub-circuit wires. I know we have to connect to the main neutral wire. So are you trying to say from the UPS Output the neutral from it should also be jodoed/twisted/

    1. Dear Azaan Kaul… you are absolutely right about the Neutral Link… Neutral Link is an electrical connectivity device which connects main Neutral wire to various other room neutral wires so that the Main Neutral Connection goes to other sub-circuit or other rooms neutral connections.<br /><br />As the above circuit diagram describes that you have to connect the UPS Output Neutral to the main

  14. Wasim Sir,
    i have quiery about your provided circuit as Automatic UPS system wiring circuit diagram (New Design Very simple) for Home or Office
    This is UPS Automatic wiring diagram no# 2.
    when in rainy season power grid supply is suddenly fluctuated can it effect automatic UPS system to create failure.

  15. what will happen if the neutral of the UPS fail and it starts to supply current while there is power supply from the grid

  16. respected Sir

    I have 135 ah type 6 batteries and 3kva inverter and a ups i wanna give connection for 4 systems & for 3 fans & 4 lights is its possible.plz help me with blockl diagram.

    note: its for office purpose

  17. Dear Sir,

    One thing is confusing me, I wish to setup the whole inverter wiring by myself so before going to start Just need to confirm one thing that at UPS out there is 2 wire that is neutral and phase. Please confirm me where to connect these 2 wires in switch board if I want to powered on an electrical fan on power outage. Please guide me in very simple words. Thank you in advance.


  18. I have one question in this..why we take input of ups from after the MCCB instead of main source. incase any maintenance or MCCB trip, still circuit will come live..because of this !!!! please clarify..

  19. Sir, in this diagram, where will the neutral from the input terminal of the inverter be connected to? I also need a diagram to connect incase a gasoline generator is used and changeover is also used

  20. Hello sir,

    I live in an apartment with generator back up. Each house gets 2kva. We have installed 2kva automatic changeover (mains and generator) switch (ACCL) for each house.

    Generator is switched on after 10-15 min of mains power failure.

    I have a ups for my wifi and laptop. Now when the ups comes on the 2kva ACCL trips. That is it goes off. I have to go to basement and reset again.

    My electrician said I can install 3kva ACCL. But society rules don’t allow as that will pull more power to my house during generator operation.

    Please advise.

    I have not checked the ups wiring whether it is same as your drawing. I will check once the electrician is available. I don’t want to try it by myself as I’m not familiar with all this.

    How to solve this problem?

  21. Can we fix a RCCB after ups in this type of circuit ??

    I.e., in home we can have 2 RCCB
    1. NEAR main supply
    2. After ups

    In this connection RCCB works after UPS ?

  22. Practical wiring and applicable, the neutral of the UPS is not connected to the main neutral supply to avoid flickering and back feed to the UPS machine which can build up to burn the UPS machine and affect sensitive equipment connected to the branch circuit. Ups loads are connected separately with an MCB as a protection.

  23. Forgive me for asking this question, if it has been asked previously. I am curious as to where does the ups neutral output connect to? It’s not shown in the wiring diagram. Do I connect the ups neutral output to the neutral link shown in the diagram? When power is restored would the main line neutral not cause the ups to blow up? Since for a few milliseconds there would be a “dual” supply of neutral. Thanks for this post by the way. Very informative!

  24. Firstly,thanks much for the idea.Can I increase the number of batteries to the UPS to increase amperage to cater for longer hours of blackouts???
    Also if am able to do so,can the UPS be able to charge the number of batteries connected???

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