For background, this is my scenario: 

I want to run a... fair number of devices off a small 850VA inverter. The one hurdle I have is that I want my house lights to keep working when there's load shedding, and that requires fiddling with the light circuits.

How does one go about wiring an inverter so that it's in-line with Eskom power? I'm a 12VDC and below kinda guy, so I don't fully understand the issues with earth/neutral bonding etc. How viable would it be to add an additional breaker, fed by the inverter, which feeds a bus bar into the light circuits? What happens to earth/neutral? Is it an issue to have 10 or 15A breakers on the other side of a 850VA source? (so the inverter will trip before the breakers ever do). I currently have 2x10A and 2x15A lighting breakers. I do understand that I'll need an electrician for this to do the work and issue the CoC, but would like to understand the process.

Please help, I don't want to burn my house down 🙃

 

The manual includes this... diagram. Maybe it's just me but I find this quite difficult to follow. It seems that I need to have common earth/neutral and effectively only use live from the AC output on the inverter. This immediately raises the concern of connecting neutral on the input and output side of the inverter. If it's in bypass, then it's the same thing, but if it's running off solar, or running off battery and the power comes back, won't that cause an issue?

Assuming I didn't misread the diagram and that my concerns are non-issues, I should be able to run the live output from the inverter into the lights bus-bar and be done, correct?

Well, it has arrived. Surely someone knows better than me? I'd really appreciate some guidance, pretty please 

I did some measurements with a current clamp in the flat we're staying in and the lights circuit is drawing more than I'd expect... (about 1.4A). Need to narrow down where the big draw is because it's all LED and CCFL in a 2br apartment. ~320w seems like a lot. I'm hoping for more like 200w.

Also, 12V panels are a pain to find. And the low OCV means high current for the same wattage. Not that I'm quite there yet, just doing the research for the next phase of this project. So far I'm very impressed with the inverter. PC and home theatre don't notice the switch-over at all, speakers don't pop, screen doesn't blink, it just keeps on going.

Bump

TL;DR will connecting the incoming neutral to the inverter's output neutral create an issue when the power returns? (switching from inverter back to bypass)

It's just not the kind of thing I want to test to find out, would rather be sure in theory before hooking it up.

Edited November 2, 20214 yr by shifttymike

Trying to wire the small UPS into your mains DB for the lights is dangerous without change-over switches, and someone who understands what they are doing. Most probably void your CoC (Certificate of Compliance) too. Rather use an extension cord with lamps for now, until you can install a full house hybrid inverter. 👍

I am not a 12 volt kinda guy ... but here is something to think about.

I am still tinkering with the solar setup ... and it is still gonna take awhile before it takes shape ... so for now I have come up with a simple 12 VDC solution.

I bought a 6.4 amp power supply/ battery charger ... which has fused 12 volt outputs X 5  ... with an 18 amp/hr battery.

I strip a lot of linear LED strip lights ( they dont seem to last much longer than 2 years) ... remove all the old bits and pieces.

Bought a 5 m long 12 VDC strip light ... cut it into strips long enough to fit inside the linear lights ... which have frosted diffuses. 

Made up a control box with relays and a 7 channel relay/receiver and a 4 button remote from Dace.

Ran 0.5 mm rip cord to each light mounted around the house ... no more darkest africa for me.

I have since come up with a better and much more modern looking setup.

I am going to get 45 degree deep strip light channel ... cut lengths about 1.5 -2 m long fit end caps and frosted cover ... mount it in the corner of each room.

Once I figue out how to do it ... I plan to fit a solar panel and a DIY lithium battery pack. 

 

 

 

 

 

 

 

 

 

 

 

 

 

2 hours ago, TimCam said:

Trying to wire the small UPS into your mains DB for the lights is dangerous without change-over switches, and someone who understands what they are doing. Most probably void your CoC (Certificate of Compliance) too. Rather use an extension cord with lamps for now, until you can install a full house hybrid inverter. 👍

That's a fair point. This is all planning for the house that we bought and are moving into in January, so it's hypothetical for now. I'm aware of the CoC issue, and for exactly that reason (having to add breakers, run new circuits etc.) we're going to need to get an electrician in anyway, so consider this thread an educational exercise, for my own curiosity: How do you wire an inverter in-line? What happens if you have a shared neutral and the power comes back?

I read somewhere about someone having an issue with the power coming back and his mains EL tripping, it had something to do with the way the inverter handed the E-N bond and it taking too long to switch, but there wasn't much detail beyond that.

If you go 100% LED only and have an average of 20w of light per room (which I think should be plenty), I count... 12 rooms including outbuilding, garage, bathrooms etc. That's 240w on a 850va (680w) inverter assuming every light is on. Given that we've just bought a house and money is tight, we won't be going full solar any time soon and I wouldn't want leads running through the house for years. I've theoretically got the capacity, and the most convenient way to light a house during load shedding is to just keep the existing lights functional, so I want to see if there are other hurdles I'm not aware of that might make this more of a challenge than I expected.

19 minutes ago, isetech said:

I am not a 12 volt kinda guy ... but here is something to think about.

I am still tinkering with the solar setup ... and it is still gonna take awhile before it takes shape ... so for now I have come up with a simple 12 VDC solution.

I bought a 6.4 amp power supply/ battery charger ... which has fused 12 volt outputs X 5  ... with an 18 amp/hr battery.

I strip a lot of linear LED strip lights ( they dont seem to last much longer than 2 years) ... remove all the old bits and pieces.

Bought a 5 m long 12 VDC strip light ... cut it into strips long enough to fit inside the linear lights ... which have frosted diffuses. 

Made up a control box with relays and a 7 channel relay/receiver and a 4 button remote from Dace.

Ran 0.5 mm rip cord to each light mounted around the house ... no more darkest africa for me.

I have since come up with a better and much more modern looking setup.

I am going to get 45 degree deep strip light channel ... cut lengths about 1.5 -2 m long fit end caps and frosted cover ... mount it in the corner of each room.

Once I figue out how to do it ... I plan to fit a solar panel and a DIY lithium battery pack. 

I like this, very resourceful! I'd actually never heard of Dace until now. We're planning on having functional, bright light in each room as well as "ambient" indirect lighting (think warm white, corner lamps, under-counter lighting). Might be worth doing a 12V solution for that, won't need an electrician. Until I decide I want to use the existing light switches then we're back to square 1 😂

My desire to do things "properly" does not agree with my budget...

1 hour ago, shifttymike said:

That's a fair point. This is all planning for the house that we bought and are moving into in January, so it's hypothetical for now. I'm aware of the CoC issue, and for exactly that reason (having to add breakers, run new circuits etc.) we're going to need to get an electrician in anyway, so consider this thread an educational exercise, for my own curiosity: How do you wire an inverter in-line? What happens if you have a shared neutral and the power comes back?

I read somewhere about someone having an issue with the power coming back and his mains EL tripping, it had something to do with the way the inverter handed the E-N bond and it taking too long to switch, but there wasn't much detail beyond that.

If you go 100% LED only and have an average of 20w of light per room (which I think should be plenty), I count... 12 rooms including outbuilding, garage, bathrooms etc. That's 240w on a 850va (680w) inverter assuming every light is on. Given that we've just bought a house and money is tight, we won't be going full solar any time soon and I wouldn't want leads running through the house for years. I've theoretically got the capacity, and the most convenient way to light a house during load shedding is to just keep the existing lights functional, so I want to see if there are other hurdles I'm not aware of that might make this more of a challenge than I expected.

I feel the excitement wanting to becoming independent from Eskom during load-shedding, and "normal" power failures. Most here have been there, but when working on house wiring, the cost can escalate rapidly to many thousands. I would first ask a local electrician for a guesstimate on the cost you can expect to pay for the labor, wiring and fittings, for your project. 👍

On the SunSynk inverters, there is an ATS 240V relay control which automatically engages an external relay to bond the earth and neutral when mains fails, and release the bond once mains restores. It will break before make, so no problems.

If I remember correctly, in that thread about the EL tripping, the cause was the EL should have been wired after the inverter, not before.

 

P.S.

My journey started many years ago, and has now culminated with a SunSynk 8.8Kw "Hybrid Parity (Super) Inverter", Lithium batteries and solar panels . I have a graveyard of UPS's, and many 12V lead acid and gel batteries. It's been an expensive journey, but enjoyable. The journey continues, with more Lithium batteries and solar panels needed.

Once the wife and children have lights during load-shedding, they will Need plugs too, and there you go..... 😂😂😂

10 hours ago, shifttymike said:

I like this, very resourceful! I'd actually never heard of Dace until now. We're planning on having functional, bright light in each room as well as "ambient" indirect lighting (think warm white, corner lamps, under-counter lighting). Might be worth doing a 12V solution for that, won't need an electrician. Until I decide I want to use the existing light switches then we're back to square 1 😂

My desire to do things "properly" does not agree with my budget...

That why I have 12 VDC motion sensors over my house ... they serve 2 purposed ... one to switch on lights for a set time and the other as PIR for the alarm. 

 

 

The cost of everything just goes through the roof ... thats why I have kept my own house cheap but effective.

I have increased the size of the batteries for my alarm ... separated the main panel from the peripherals ... added my router.

I have 3 lights which positioned correctly light up the enitre inside of my house ... which half 12 hour backup power.

I have a small 600 watt inverter with a 105 amp/hr deep cycle lead acid battery ... got it when load shedding started in 2008 ... replaced the battery a couple years ago ... it runs the TV ... CCTV and all the other electronics on the electronics wall. 

I would love to piss R150k against the wall ... considering I can do the entire installation and sign it off ... I have no desire to waste that kind of money at this point in time.

I almost completely debt free ... and want to stay like that for as long as possible. 

If the 2 hour load shedding becomes a problem .... I get in my vehicle and go for coffee somewhere with the family and spend some quality time with them

the only time power becomes a real problem is when we have outages longer than 8 hours on a hot day ... because it affects the fridge and deep freezes ... I have a 5 kva generator which can run everything including my geyser (reduced the element to a 1 kw) for many hours. 

By the way the Dace has 4 buttons but can switch 7 12 VDC relays by pressing more that one button at a time. 

 

 

 

 

 

 

 

11 hours ago, TimCam said:

Most here have been there, but when working on house wiring, the cost can escalate rapidly to many thousands. I would first ask a local electrician for a guesstimate on the cost you can expect to pay for the labor, wiring and fittings, for your project. 👍

I've contacted a local contractor, although despite being qualified to sign off on installations, I'm still not 100% confident that without knowledge of the inner-workings of the inverter, he'd be able to safely say that a given solution would work without testing it. I guess I should find someone who specifically does solar, this would be more in their wheelhouse.

11 hours ago, TimCam said:

If I remember correctly, in that thread about the EL tripping, the cause was the EL should have been wired after the inverter, not before.😂

This just raises more questions, there's no EL on this inverter, just a regular plug outlet. Nowhere does it say you need to add earth-leakage 🤔

2 hours ago, isetech said:

The cost of everything just goes through the roof ... thats why I have kept my own house cheap but effective.

...

I would love to piss R150k against the wall ... considering I can do the entire installation and sign it off ... I have no desire to waste that kind of money at this point in time.

For sure, that's kind of my goal as well: to keep costs to a minimum while getting the maximum value. I have no debts aside from the house we just bought (that is to say that I have a lot of debt ) and installing a large system would bring that to a swift end. My main goal is to figure out why this can't all be done for relatively little money. That LiFePO4 battery packs quite a punch and I don't have to worry about going over 30% DoD. The inverter, at 680w, is more than enough for my 250w lighting budget (and then some). Why does it have to cost tens of thousands to stay out of the dark?

Now for the questions:

• This inverter has no EL, just a resettable fuse and overload protection (both of which are for overcurrent). What happens if there's a short from live to earth and mains power is dead (load shedding)?
• The diagram in the manual says that you can wire it into the db, except there's no EL in that diagram, before or after the inverter. If it has to go after, then it implies that your entire load has to run in-line which is obviously not viable with an 850w inverter. So what is the wiring supposed to look like? Can you have EL both before and after? If you have a common neutral and earth but live goes directly into the circuit breaker, then I can't see how the EL would be functional with no reference to the current in the secondary live wire.
• Off the back of the last question, would it perhaps be an option to have a, say 10A breaker in the main db to feed the inverter, then a sub-db with EL and all the light circuits? Something like this: https://leroymerlin.co.za/db-board-populated-8-ways-surface-mounted-lesco-81422450. This would avoid creating the neutral loop as the secondary side is isolated, but I don't fully understand the repercussions of having a second EL. Without a schematic, it's difficult to know, but there must be some kind of convention. Surely I'm not the first to want to wire the essentials in-line?

Also, at this stage I only have 1 kid and she's not even crawling yet, so she doesn't care much about the plugs being wired and it's probably for the best if they aren't

My wife mainly just wants to be able to cook and see what she's doing, and for that we have a gas stove, so as long as the lights and the internet stay up, there's peace in the world. I plan to split the oven's power between the gas igniters and clock, and the oven elements/fans so that you don't have to get the matches out to use the stove when there's load shedding. I'd go with the Veti modular plugs so that I can have a standard plug and dedicated plug in the existing flush-mount box. One in the kitchen (stove), bedroom (misc), lounge (TV) and office (laptop/screen). The idea is that in a few years, we can upgrade to something bigger and carry more of the load. The house wiring I'd like to mostly do once, so 2.5mm cabling everywhere etc.

Found this thread (missed it in earlier searches): 

Was quite enlightening, although not exactly the same scenario (I'm intending to feed my inverter post-EL). I guess the answer here is that "it depends" on how my inverter handles the E-N bond, and it's probably going to be safest to run a sub-db with its own EL. Although if I have a common earth then am I not just creating a neutral loop again? 🤔

What might be helpful is to have an electrician test the inverter and confirm its behaviour. Then we can start making informed decisions.

Edited November 3, 20214 yr by shifttymike

Those small UPS units are not designed for anything other than to create a safe shutdown period for the programs open on a PC ... which then brings us to earth leakage protection ... a dedicated socket outlet feeding sensitive electronic equipment does "not" have to be on earth leakage.

Something I learnt recently ... if setup correctly the UPS can automatically shut down your PC ... if the power drops below a specific voltage or cuts out completely.

I strongly advise that you dont use the small UPS ... the neutral/earth is not bonded on those units so they have a floating voltage of around 80+VAC.

 

 

 

 

 

 

I see you mentioned a kid ... all the more reason you need to be very careful ... make sure all the socket outlets in your house have shutters in the socket outlets. 

16 minutes ago, isetech said:

Those small UPS units are not designed for anything other than to create a safe shutdown period for the programs open on a PC

It's not a UPS, it's a small inverter with a built-in MPPT charger. The manual for it has a diagram showing how to wire it into your db, although there's no earth in the diagram 🤔

I certainly wouldn't wire a UPS into my house's power because you're right, they're not designed for that.

14 minutes ago, isetech said:

I see you mentioned a kid ... all the more reason you need to be very careful ... make sure all the socket outlets in your house have shutters in the socket outlets. 

Will do. She's not crawling yet, but as soon as she's mobile, we'll be baby-proofing everything.

3 hours ago, shifttymike said:

It's not a UPS, it's a small inverter with a built-in MPPT charger. The manual for it has a diagram showing how to wire it into your db, although there's no earth in the diagram

Looking at the diagram above, check with a multi-meter set to Ohm's between N on the "Wall Plug" and N on the "inverter O/P".

There should be 0 Ohm's, if not the diagram is missing connections.

The way it's wired, the lights will Always work through the inverter, as there is no changeover. Live from the inverter O/P is wired permanently to the lights.

Your electrician should wire in a bypass switch in case the inverter fails.

On the solar side, what size panel can you connect?

 

Edited November 3, 20214 yr by TimCam

6 minutes ago, TimCam said:

There should be 0 Ohm's, if not the diagram is missing connections.

Yip! 0 Ohms between mains neutral and inverter output.

7 minutes ago, TimCam said:

The way it's wired, the lights will Always work through the inverter, as there is no changeover. Live from the inverter O/P is wired permanently to the lights.

Your electrician should wire in a bypass switch in case the inverter fails.

Exactly. This is what I meant by "in-line", I don't want to have a switch-over since the inverter handles switching between mains/solar/battery as required. It prioritises solar, then mains, then battery. The bypass switch makes sense, I will ask about this.

9 minutes ago, TimCam said:

On the solar side, what size panel can you connect?

800W total. It's a bit of a pain because the panels need to be 12V (ocv of 17-21), so they're kinda hard to source. I did find a 300w panel on Bid-or-buy for R1700, but who knows what it actually is? 😬

When I do this, I understand I'll need a sub-db for the DC side. Due to the nature of solar panels and lights, I won't be using the lights when the sun is out so it will be mostly to keep the electricity cost of the system down and increase the battery runtime (and consequently lifetime) in the day. My office needs about 150w max and the home theatre is about the same.

You will need a Sub-DB or at least be able to split your DB into 2 sections.  Based on the diagram above the inverter is feeding the whole DB, but because you only want to feed certain circuit you will be required to split your neutral bar between the loads which will be fed from Eskom and the ones fed through the inverter.

The inverter will need to be connected before your earth leakage otherwise it is going to trip your EL each time it switches over

This is the db. I won’t accept judgement because we don’t live there yet, I promise to at the very least clean it and redo the labels 😅


But it looks like there’s probably enough room to expand. Apparently things have been shuffled around since I was last there.

8 minutes ago, Bloubul7 said:

The inverter will need to be connected before your earth leakage otherwise it is going to trip your EL each time it switches over

So if I understand this correctly, I’ll have 2 EL breakers. One for the Eskom fed circuits and one after the inverter, right? Same earth connection to both. And a second neutral bus bar for the inverter into the various beakers.

1 hour ago, shifttymike said:

So if I understand this correctly, I’ll have 2 EL breakers. One for the Eskom fed circuits and one after the inverter, right? Same earth connection to both. And a second neutral bus bar for the inverter into the various beakers.

This inverter is not a full house inverter, but operating as an appliance through a 16A plug point. Therefore it is protected by your EL in the DB.

All lights and geyser in your house are not wired through any EL. So no worries about needing any other EL. Just get a Sparky to do the wiring. 😀

@shifttymikesearch the forum. There is various threads with diagrams how to wire an inverter correctly. 

@shifttymike have you reached consensus on the positioning of E/L prior+post inverter, and on the sharing of Neutral from Grid In and Inverter Out, or alternatively keeping them separated and bonding Inverter Out Neutral to Earth?

Those are the only questions left for me in my own similar scenario... I too have a pure sine wave 850VA hybrid inverter, which plugs into grid with a standard appliance plug. 

Have you built your system yet, or has your design strategy changed?

On 2021/11/03 at 7:16 PM, shifttymike said:

So if I understand this correctly, I’ll have 2 EL breakers. One for the Eskom fed circuits and one after the inverter, right? Same earth connection to both. And a second neutral bus bar for the inverter into the various beakers.

I've confirmed my understanding, more or less. Despite the inverter not being a "whole house inverter", I've finally figured out through trial and error the following:

• There is zero earth leakage protection on the inverter. If there's an earth fault after the inverter while it's running in bypass, the house ELCB will trip and the inverter will start inverting and you'll get electrocuted by that instead of Eskom. Not ideal
• An ELCB after the inverter, regardless of whether the inverter is inverting or on bypass, does not work because the small inverters don't do E-N bonding. I tested up to 35mA and it just looked at me. This functionality can be added with a purpose-built box like this or possibly just a NC contactor with the coil powered by mains (there may be some regulatory stuff here about mixing mains and inverter power)
• As with the bigger inverters, adding E-N bonding will require you to run the inverter off an un-protected circuit as it will cause the mains ELCB to trip whenever the power returns, a problem reported in a few posts on this forum

I've probably spent as much on cabling and breakers as I have on my inverter, but the idea is to future-proof it so that when I upgrade, I don't have to change much. I haven't implemented the E-N bonding and ELCB yet, but it's only powering the light circuits and non-earthed equipment (TV, laptop, router etc.)

Here's my lighting db. There's a 2-pole isolator plus a CB per light circuit, the ones in the main db are not in use but may be re-purposed to power the inverter in future as they're not earthed. It works a treat. Having the lights in-line (no-changeover switch) makes a big difference.

Oh, and I will get a "sparky" to double check all of this. I'm fairly confident it's all safe and mostly to code, but will need someone who does this for a living to confirm.