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Changover switch on 3kw setup

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I have a mobile trolley 3kw inverter setup which I am considering connecting to the DB. Currently my TV, laptop and fridge is connected to the setup. Once load shedding starts, the inverter setup automatically powers these items without any delay. Once load shedding ends and Eskom returns, these items are powered by Eskom and the battery charged by Eskom. I want the same when the inverter is connected to the DB. Once load shedding starts, my essentials need to remain on without cutting power or me needing to go flip a switch. The idea is to connect lights and plugs as essentials on the output of the inverter.

Here is where I am confused - do I need an automatic changeover switch for this? I have seen many installs without a changeover switch, or that have manual changeover switches. Many of the threads out there also suggest a changeover switch is only required to disconnect the inverter for maintenance etc. I spoke to a mate that said a changeover is not required because the inverter acts as a UPS. However, I am not sure how the wiring of this will work? How I envision the setup is:

Main DB:

  • 32A CB as a main switch to inverter

Sub DB:

  • 32A AC in CB
  • 20KA SPD
  • 10A AC out CB which links to plugs / lights (Will serve as overload protection on the inverter)
  • Not sure if I require earth leakage as well? If so, what amperage on the 3kw inverter?

However, I think the ATS is required because if it is absent there will be two live power sources running to the plugs/lights simultaneously which does not seem right.

Lastly, I see most ATS are rated 63A. Will a 3kw inverter activate an ATS rated at 63A? I have read on a few threads that the 3kw inverters do not activate the ATS at 63A, so what is the alternative as all ATS seems to be 63A or above?

 

9 hours ago, Wimmas said:

I have a mobile trolley 3kw inverter setup which I am considering connecting to the DB. Currently my TV, laptop and fridge is connected to the setup. Once load shedding starts, the inverter setup automatically powers these items without any delay. Once load shedding ends and Eskom returns, these items are powered by Eskom and the battery charged by Eskom. I want the same when the inverter is connected to the DB. Once load shedding starts, my essentials need to remain on without cutting power or me needing to go flip a switch. The idea is to connect lights and plugs as essentials on the output of the inverter.

Here is where I am confused - do I need an automatic changeover switch for this? I have seen many installs without a changeover switch, or that have manual changeover switches. Many of the threads out there also suggest a changeover switch is only required to disconnect the inverter for maintenance etc. I spoke to a mate that said a changeover is not required because the inverter acts as a UPS. However, I am not sure how the wiring of this will work? How I envision the setup is:

Main DB:

  • 32A CB as a main switch to inverter

Sub DB:

  • 32A AC in CB
  • 20KA SPD
  • 10A AC out CB which links to plugs / lights (Will serve as overload protection on the inverter)
  • Not sure if I require earth leakage as well? If so, what amperage on the 3kw inverter?
    9 hours ago, Wimmas said:

     

However, I think the ATS is required because if it is absent there will be two live power sources running to the plugs/lights simultaneously which does not seem right.

Lastly, I see most ATS are rated 63A. Will a 3kw inverter activate an ATS rated at 63A? I have read on a few threads that the 3kw inverters do not activate the ATS at 63A, so what is the alternative as all ATS seems to be 63A or above?

 

@WimmasMy first question would be do you want to do the wiring in the db yourself? Drawing a conclusion from the questions you ask my assumption is that you are not a qualified installer or electrician. I will answer some of your questions but do not attempt to do the wiring in the db if you are not qualified.

1. No ATS, MTS for bypassing inverter under maintenance.

2. You need to split the essential loads from the main db to a new essential db wiring the lives and neutrals to the new db board, the earth's would be common.

3. You need seperate mcb's for plug curcuit( 20A)  and light curcuit(5A or 10A) you can't wire lights and plugs throught one mcb.

4. Your mcb needs to accommodate your wire size.

5. Yes you would most definitely need a second earth leakage with double pole mcb as isolator before the earth leakage and Spd. You will need a non permanent earth/ neutral bond on output of the inverter.

6. Last but not least you will need a COC.

What inverter do you currently have?

 

13 hours ago, Wimmas said:

I have a mobile trolley 3kw inverter setup which I am considering connecting to the DB. Currently my TV, laptop and fridge is connected to the setup. Once load shedding starts, the inverter setup automatically powers these items without any delay. Once load shedding ends and Eskom returns, these items are powered by Eskom and the battery charged by Eskom. I want the same when the inverter is connected to the DB. Once load shedding starts, my essentials need to remain on without cutting power or me needing to go flip a switch. The idea is to connect lights and plugs as essentials on the output of the inverter.

Here is where I am confused - do I need an automatic changeover switch for this? I have seen many installs without a changeover switch, or that have manual changeover switches. Many of the threads out there also suggest a changeover switch is only required to disconnect the inverter for maintenance etc. I spoke to a mate that said a changeover is not required because the inverter acts as a UPS. However, I am not sure how the wiring of this will work? How I envision the setup is:

Main DB:

  • 32A CB as a main switch to inverter

Sub DB:

  • 32A AC in CB
  • 20KA SPD
  • 10A AC out CB which links to plugs / lights (Will serve as overload protection on the inverter)
  • Not sure if I require earth leakage as well? If so, what amperage on the 3kw inverter?

However, I think the ATS is required because if it is absent there will be two live power sources running to the plugs/lights simultaneously which does not seem right.

Lastly, I see most ATS are rated 63A. Will a 3kw inverter activate an ATS rated at 63A? I have read on a few threads that the 3kw inverters do not activate the ATS at 63A, so what is the alternative as all ATS seems to be 63A or above?

 

The 63A on the ATS is the maximum current and has no bearing on its operation even on a small inverter. 

The main feed to the inverter can be 20A instead of 32A.

Why limit the output from inverter to 10A. I presume the inverter can provide 13A output. 16A gives some head room. 

Also pay attention to regs when fiddling with the DB as has been mentioned. 

  • 1 month later...
  • Author
On 2023/06/04 at 7:34 AM, TaliaB said:

@WimmasMy first question would be do you want to do the wiring in the db yourself? Drawing a conclusion from the questions you ask my assumption is that you are not a qualified installer or electrician. I will answer some of your questions but do not attempt to do the wiring in the db if you are not qualified.

1. No ATS, MTS for bypassing inverter under maintenance.

2. You need to split the essential loads from the main db to a new essential db wiring the lives and neutrals to the new db board, the earth's would be common.

3. You need seperate mcb's for plug curcuit( 20A)  and light curcuit(5A or 10A) you can't wire lights and plugs throught one mcb.

4. Your mcb needs to accommodate your wire size.

5. Yes you would most definitely need a second earth leakage with double pole mcb as isolator before the earth leakage and Spd. You will need a non permanent earth/ neutral bond on output of the inverter.

6. Last but not least you will need a COC.

What inverter do you currently have?

 

In two minds at the moment about wiring myself. I feel there are so many "solar experts" that have popped up in recent months and every other guy is now an installer. I would like to do my due diligence and understand the wiring so that some "expert" does not take my money and do a half job.

  1. The reason I posted this thread is to ask whether or not an ATS is required. My whole objective is to have uninterrupted power supply when Eskom goes off. I have seen many installations without any sort of changeover switch. I do not want to walk to my DB and flip a switch when Eskom goes off. I still do not have the answer to this.
  2. Can I split the essentials on the main DB? My wiring diagram will provide a better idea of what I mean
  3. My essentials will only be lights and plugs. Inverter is 3000w so it cannot push more than 13A. I thought a 10A breaker would suffice as one cannot easily find a 13A breaker. The idea is to trip/switch off the inverter if it reaches 10A/13A output.
  4. Understood
  5. I have seen many installations without an earth leakage, only a CB. There are mixed opinions on this. I am still unsure. What amperage EL would I require?
  6. Understood

I have a Must 24v 3kw 60A inverter

On 2023/06/04 at 10:37 AM, Scorp007 said:

The 63A on the ATS is the maximum current and has no bearing on its operation even on a small inverter. 

The main feed to the inverter can be 20A instead of 32A.

Why limit the output from inverter to 10A. I presume the inverter can provide 13A output. 16A gives some head room. 

Also pay attention to regs when fiddling with the DB as has been mentioned. 

I have read a few threads where people are complaining that their ATS is not activated on 3kw inverters. I would like to avoid buying multiple ATS to find the correct one.

Main feed of 32A is recommended on the inverter manual.

16A on output will push the inverter beyond its capabilities. I want it to cut/switch off at 10A. I have a very small household and will likely not reach 10A during loadshedding.

I have looked at a few wiring diagrams online as well as the one in the Microcare inverter manual, and the below picture is where I am currently at. Please let me know if this makes sense.

Screenshot 2023-07-11 181138.png

1 hour ago, Wimmas said:

In two minds at the moment about wiring myself. I feel there are so many "solar experts" that have popped up in recent months and every other guy is now an installer. I would like to do my due diligence and understand the wiring so that some "expert" does not take my money and do a half job.

  1. The reason I posted this thread is to ask whether or not an ATS is required. My whole objective is to have uninterrupted power supply when Eskom goes off. I have seen many installations without any sort of changeover switch. I do not want to walk to my DB and flip a switch when Eskom goes off. I still do not have the answer to this.
  2. Can I split the essentials on the main DB? My wiring diagram will provide a better idea of what I mean
  3. My essentials will only be lights and plugs. Inverter is 3000w so it cannot push more than 13A. I thought a 10A breaker would suffice as one cannot easily find a 13A breaker. The idea is to trip/switch off the inverter if it reaches 10A/13A output.
  4. Understood
  5. I have seen many installations without an earth leakage, only a CB. There are mixed opinions on this. I am still unsure. What amperage EL would I require?
  6. Understood

I have a Must 24v 3kw 60A inverter

I have read a few threads where people are complaining that their ATS is not activated on 3kw inverters. I would like to avoid buying multiple ATS to find the correct one.

Main feed of 32A is recommended on the inverter manual.

16A on output will push the inverter beyond its capabilities. I want it to cut/switch off at 10A. I have a very small household and will likely not reach 10A during loadshedding.

I have looked at a few wiring diagrams online as well as the one in the Microcare inverter manual, and the below picture is where I am currently at. Please let me know if this makes sense.

Screenshot 2023-07-11 181138.png

You can use a 20A E/L if you are going to never use more than that when on grid or during LS. Bear in mind a 10A CB will allow more than 16A for quite a long time before it trips and the inverter will trip before the CB. 

Also because you have seen many without a E/L does not mean it is OK. It's against regulations to have sockets on non E/L protected circuits and is a major safety risk. 

Too many things to comment on your circuits. 

Some circuits not complete or unclear. Are you never going to use more than 10A even with grid on. The input to the E/L is not shown completely. 

  • Author
2 hours ago, VirWat said:

Honestly, no.

No sense at all.

Thanks for the comment. Please advise with what you do not agree?

1 hour ago, Scorp007 said:

You can use a 20A E/L if you are going to never use more than that when on grid or during LS. Bear in mind a 10A CB will allow more than 16A for quite a long time before it trips and the inverter will trip before the CB. 

Also because you have seen many without a E/L does not mean it is OK. It's against regulations to have sockets on non E/L protected circuits and is a major safety risk. 

Too many things to comment on your circuits. 

Some circuits not complete or unclear. Are you never going to use more than 10A even with grid on. The input to the E/L is not shown completely. 

Understood, E/L will be installed as recommended.

I am a handy individual  whom has not got problem with compensating for someone's knowledge. I have a problem paying or a fly by night who'd like to charge for something simple like mounting an inverter and battery.

3 hours ago, Wimmas said:

The reason I posted this thread is to ask whether or not an ATS is required. My whole objective is to have uninterrupted power supply when Eskom goes off. I have seen many installations without any sort of changeover switch. I do not want to walk to my DB and flip a switch when Eskom goes off. I still do not have the answer to this.

Your inverter has an internal changeover switch rated to the pass-through current. Short answer is you don't need an ATS. A static bypass switch/manual transfer switch (MTS) is however recommended to isolate the inverter during maintenance.

  • Author
5 hours ago, VirWat said:

Show your circuits connected to the 2 Neutral bars.

E/L no wiring.

SPD feeding the inverter?

Wimmas.jpg

I have attached a picture of my main DB as well as what I think the wiring of it looks like.

How it is currently wired is E/L feeds into plugs only.

I am guessing neutral bar 1 is connected directly from Eskom supply and feeds into the stove, geyser and lights and neutral bar 2 is connected after E/L and feeds into plugs.

Where should the SPD be wired if not after the AC IN CB that feeds into the inverter? I thought the whole idea of the SPD is to protect the inverter from surges.

20230320_135745 (1).jpg

Main DB.jpg

Your AC supply to the inverter comes from the bottom of the SPD, and not from the bottom of the 32A CB to the left of the SPD. (same place as where the SPD gets it's feed)

Surge protection devices does not have a in and out for L & N. Only got a L & N connection in and a earth connection(s) out.

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