# Interest group forums > Electrical Contracting Industry Forum > Electrical Load Shedding Forum >  Adding 2 Alternative supply DB's

## LightsOn

This is my tentative plan, please let me know if I've missed anything

I've labelled the original Eskom DB as DB1 and I'm adding DB2 and DB3.
DB2 and DB3 have warning labels, Alternative supply labels and pilot lights.

I will refer to them as
(eskom) DB1
(inverter) DB2
(combiner) DB3
in this thread so you don't have to remember which is which, but on the DB's there are only labels such as DB1, DB2 and DB3.

The 2400W inverter's 2 output wires each go via a 12A fuse, to earth leakage (inverter) DB2, that feeds input B of a relay. (used when the relay coil is powered off)

The Relay is double pole, double throw 250V 10A.

A normal 16A plug brings power into (inverter) DB2, the earth is joined to the output cable's earth.
Both of the live and neutral wires from this cable each go via 12A fuses to input B of the relay.
(after the fuses) they also feed a 12v power adapter, that powers the relay's coil.

The fuses protect against hypothetical failure of the relay.

The output of the relay feeds 2 terminal-bus-bars inside (inverter) DB2, the live output bus bar feeds a 10A breaker labelled "Plugs and DB3"

A single Surfix 1.5mm live, neutral, earth (+ shielded) cable is split inside wall junction boxes, and carries the (inverter) DB2 output to wall-mounted multi-plugs and also feeds (combiner) DB3.

The multi-plugs all feature built-in always-on pilot lights and these multi-plugs will be labelled "Alternative supply"

Inside (eskom) DB1. A new breaker labelled "DB3" has been added. This breaker is fed from the earth leakage live output.

Red and black wires carrying this breaker's output, as well as the earth leakage neutral bus bar feed the changeover switch in (combiner) DB3.

(combiner) DB3 is installed next to (eskom) DB1.

On the left, (combiner) DB3 has an isolation switch for the supply from (inverter) DB2.
Next to the Isolation switch is the changeover switch, it's top input is the output from the isolation switch, it's bottom input comes from (eskom DB1)

The changeover switch output feeds a output neutral terminal-bus-bar and feeds breakers for (digital gas) Geyser and Lights, respectively.

Inside DB3 I have 3 pilot lights
1. Eskom supply
2. Alternative supply
3. Output enabled (the output of the changeover switch)

I will add some pictures.

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## LightsOn

Main questions for these pictures
Q1. Are the labels good for DB1 and DB2 and DB3?
Q2. Is it fine to have the red and black wires between the DB's visible beneath the surface of the wall? Should I put a piece of white plastic over it?
Q3. I've seen the regulations call for an isolator from the alternative supply, but it seems strange that it doesn't also call for an isolator for the normal supply in DB3. Is it sufficient to only have an isolator for the alternative supply?

Currently, live eskom supply will be isolated from DB3 if the DB3 switch on DB1 is turned off.
The neutral AND live will be isolated from DB3 if either DB1 Mains or DB1 EL is turned off.

Q4. What do you think of my pilot lights?
The top pilot light is connected to the output of the changeover switch.
The bottom pilot light is connected to the bottom (eskom) input of the changeover switch.
The middle pilot light is connected to the output of the alternative supply isolator in DB3.

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## LightsOn

DB2 is a work in progress, I'm going to swap it out with a bigger DB that can hold a relay.
DB2 will take the feed from a plug and from inverter.
Those will go to a 3 pole relay.
The live and neutral (common) outputs of the relay will feed the "Plugs" breaker in DB2. (to be relabelled as "Plugs and DB3")
(not all plugs, only the alternative supply plugs, that will be labelled as such and include pilot lights on every plug)
The 3rd pole of the relay will tie the inverter neutral to earth before the earth leakage.
The inverter's live and neutral will feed the earth leakage and the earth leakage output will go into the relay.

So the end result will be
1. When there's eskom power, it flows from a plug through the relay to "Plugs and DB3" breaker.
2. When there's no eskom power, the inverter's neutral will be bridged to earth, and the inverter's neutral and live will flow the EL to the relay, and then to the "Plugs and DB3" breaker.

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## LightsOn

I read somewhere that only the inverter's output should go through the EL, which is why I planned and wrote as above.

But I did find it a bit strange, prior to having researched this, I would have done this:

Normal:              DB1 > EL > Plugs breaker > Plug > Relay > EL > (alternative supplyable) Plugs
LoadShedding : Inverter (earth neutral tied) >            Relay > EL > (alternative supplyable) Plugs

But now I'm planning to do this
Normal:              DB1 > EL > Plugs breaker > Plug > Relay > (alternative supplyable) Plugs
LoadShedding : Inverter (earth neutral tied) > EL   > Relay > (alternative supplyable) Plugs

It's much of a muchness really. I just previously assumed double earth leakage protection can't hurt and can only be a good thing.

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## GCE

You appear to be heading towards a disaster at best case scenario and burning down the house in the worse case scenario.

Rather get a suitable qualified Electrical contractor to carry out your install

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## LightsOn

I have consulted with a contractor whom I know. I will get him to check everything and correct whatever is needed and finish the job to get CoC.

Not everybody has R200k lying around to pay a contractor to do everything for them to go off grid. And not everybody is able to earn a living and function without electricity for 1/3 of the day.

I am technically capable, experienced in electronics engineering, just not entirely familiar with everything SANS related.

It's common for plumbers to get assistants to do the grunt work, then they check/correct and sign off on it, and likewise for Electricians.

So please relax. I am checking what I'm doing and it will go through proper procedures when finalized.

If you want to be helpful, that is appreciated.

But you can calm your fears. I'm not the first of a million South Africans "winging it". I am not at all "winging it".
I am a unique individual, skilled and experienced in similar areas to this. I am making best efforts to do everything to standard and will ensure that everything is standards compliant and certified when it's done.

If you want to worry about something, I'm sure there are millions of South African buildings with totally bodged installations with no plans or intentions of ever being compliant.

I am earnestly trying to be standards compliant and if you want to provide any assistance that's much appreciated.

If replying to my threads doesn't interest you, you're welcome to find something else to do that you enjoy.

I sincerely hope this message finds you well and thank you for your responses thus far.

Whenever I am in doubt, I do ask. And if you see something that you think I've missed I appreciate when you let me know.

From reading various threads on this forum the general impression that I've gotten is that people are working towards a common goal of safety and standards compliance.

I am fully in support of that goal.

Thanks

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## LightsOn

Regarding your hyperbole




> You appear to be heading towards a disaster at best case scenario and burning down the house in the worse case scenario.


It doesn't achieve anything. The fictional dying in a fire of hell inferno without any reason is really low quality dialogue.

If there's some mistake that I've made, or something mentioned in the tentative plan that is not safe or standards compliant, I would really like to know.

Let's be intelligent, constructive, objective and factual.

If you can't do that, then don't bother replying.

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## Isetech

Unfortunately the elctrical industry race to the bottom is a reality. I see it everyday I go to work.

 Will you even need a trade test to do electrical work in years to come, I doubt it. 

Everyday I open social media platforms, I see people posting pictures of illegal installations, I dont even bother commenting anymore.

This recent fiasco with stage 6 has turned the entire solar and elctrical industry on its head. It has turned into chaos.

You get a few jokers threatening that there is going to be legal action, fines for unregistered systems,  blah, blah, blah.

Most electrician dont even understand the regulations, passed the test using old papers, dont have a clue how to even fill out a COC. 

How often do you even see a qualified electrician on a site? I see lots of labourers with time served experience and that's about it.

The good ol days of tradesmen, IE's and MIE's is going to die with us older folk still left in the industry.

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## LightsOn

@Icetech, this comes as no surprise, but isn't nice to see confirmation of it.

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