Bare copper conductor.

Thank you!

Another question - due to this being a backup system and no solar panels - if we have a prolonged outage and I need to charge the battery via a generator, will I be able to just connect the 3-way plug which I normally plug into the wall socket, to the generator to charge the battery?

I was just thinking of the supply of your inverter using a wall socket might trip the earth leakage in the db board hence the reason the supply to the inverter is connected before the earth leakage unit with dedicated curcuit breaker including a earth neutral bond in the form of a relay or contactor on the output side when in island mode. Try it and see what happens

8 minutes ago, Wimmas said:

Thank you!

Another question - due to this being a backup system and no solar panels - if we have a prolonged outage and I need to charge the battery via a generator, will I be able to just connect the 3-way plug which I normally plug into the wall socket, to the generator to charge the battery?

If your generator is connected via a 3 position transfer switch the socket you are using should have power if you don't have a transfer switch you could connect straight to the generator

Edited February 27, 20233 yr by TaliaB

My proposed schematic for stand-alone system. To prevent the RCB from tripping in the DB box don't connect the ground to the inverter input but add an RCB on the output side for protection.

17 hours ago, JohannFer said:

My proposed schematic for stand-alone system. To prevent the RCB from tripping in the DB box don't connect the ground to the inverter input but add an RCB on the output side for protection.

Thanks for the info!

Just a few questions on your diagram:

1. What is the surge protection before the inverter?
2. Between the inverter and battery I plan on putting the DC breaker instead of a fuse, is that fine? Seems like your diagram has a fuse.
3. Do you then run a ground wire at the AC output?

Was thinking I should get a small DB to house the breakers as well.

The surge protection before the inverter is to protect the inverter.

Yes, you can put in a DC circuit breaker but a fuze, if ever required to pop, is much faster.

Yes, you run a ground wire from the output or the earth leakage wll not work.

I am battling to find a 20KA 2p surge arrestor - sold out all over and ETA is only end May. Will a surge protector plug on the AC side suffice or will I be taking too much of a risk on the inverter without the 20KA 2p surge arrestor?

Going to buy a Onesto ready board like this: https://diyshop.co.za/products/db-ready-board-mini it comes standard with a 63A earth leakage. Must I get a 25A RCD or can I use the standard 63A that comes with the board?

Have you tried e-glow, I buy most of my goodies from there.
https://e-glow.co.za/collections/spd-dc-surge-protection

 

36 minutes ago, WannabeSolarSparky said:

Have you tried e-glow, I buy most of my goodies from there.
https://e-glow.co.za/collections/spd-dc-surge-protection

 

I see they have a 30KA and upwards. From this video it seems I need 20KA: 

 

Will the 30KA work?

4 minutes ago, Wimmas said:

Will the 30KA work?

That just means it will handle a larger current surge.
The electricians on the forum will be able to provide a better more definitive answer

I didn't follow this tread and will leave others to comment further.  However, I saw you reference a surge protector and gave this link:
https://www.takealot.com/united-electrical-16a-high-surge-protection-3-pin-plug-top/PLID72796115

In theory, a surge protector is a good thing, but these plugs are a TOTAL waste of time and MONEY.  Others might disagree.

As far as I know it is an Ellies product.  The first problem is that it use a MOV.  (Metal Oxide Varistor).  These are round disk-like components normally blue in colour but sometimes also a yellowish or red.  They are cheap components that degrade over time and become ineffective.  The right component that SHOULD be used is a Bipolar Transorb which is very, very fast.  Transorbs do not degrade, but they can blow up if their max power is exceeded.  A real surge protector would require many components and might even use a gas-arrestor.  The transorb is fast, but cannot handle sustained power absorption.  A Gas-arrestor is slow, but can dissipate power over longer duration than a transorb.  In combination, the weakness of one is the strength of the other.  So its a good combination to use.  A bit of a serial inductance would help in slowing the sharp rise-times of transients.

MOVs are used in most equipment, simply because they are cheap and give ***some*** protection.

OK, so they give some protection, so why not use a plug like that?

These plugs have been designed by an IDIOT  !!!!

The MOV sits in the deep recess of the plug and uses spring contacts to press on the rear of L & N prongs.  The problems are many:

1. The spring is made of thin wire which just can't handle any decent amount of current
2. The spring is a spiral. It is a coil and thus will have inductance.  You do not want an inductance in that pathway!!!!
3. Being a spring, it will be made of some sort of steel (spring steel) which will have a relatively high electric resistance.
4. The contacts are just spring loaded and are bound to have much higher resistance than a proper screw or clamp termination.

Perhaps someone has redesigned the product.  Running thick wires from the MOV and terminating them with the cable would be a good start.  But I doubt it.  People that have these plugs can open them up to see if the construction is still as stated above.

I am out of touch with prices, but in quantity, a MOV might cost R3 to R5.  A transorb maybe 10x more.   Transorbs must be carefully specified for the voltage.  You get transorbs that snub as low as a few volts.  For AC you need a device that is bipolar and clamps at about 340+ V.  One would need to reference the datasheet.  They come in 600W and 1.5KW ratings and look like a diode.  I am sure you will also get much bigger devices rated for even higher (instantaneous) power handling.

Just an update:

My existing battery cabinet was too small, so I ordered a new one which I will be receiving tomorrow. All other parts already received.

I have started wiring my ready DB and would just like to confirm one last time that I have everything correct in terms of wiring. Below a diagram which hopefully makes sense. Please let me know if I am correct:

I should be done with the build tomorrow and will definitely post some pics. Thanks for everyone's input, I really appreciate it!

1 hour ago, Wimmas said:

Just an update:

My existing battery cabinet was too small, so I ordered a new one which I will be receiving tomorrow. All other parts already received.

I have started wiring my ready DB and would just like to confirm one last time that I have everything correct in terms of wiring. Below a diagram which hopefully makes sense. Please let me know if I am correct:

I should be done with the build tomorrow and will definitely post some pics. Thanks for everyone's input, I really appreciate it!

All seems good. 

I completed the build today and am very pleased with how it came out. I now need to figure out all of the correct settings for the battery and inverter. One annoying thing is the inverter fans come on every few seconds.

Herewith some images of the completed build:

2 hours ago, Wimmas said:

I completed the build today and am very pleased with how it came out. I now need to figure out all of the correct settings for the battery and inverter. One annoying thing is the inverter fans come on every few seconds.

Herewith some images of the completed build:

Well done, and it has presence😎

On 2023/02/27 at 10:48 PM, JohannFer said:

My proposed schematic for stand-alone system. To prevent the RCB from tripping in the DB box don't connect the ground to the inverter input but add an RCB on the output side for protection.

Kindly advise how the earth works in this diagram?

From what I have read the SPD needs to be grounded to function correctly.

Would I need to wire as follow:

Connect the ground on the wall socket, but bypass the AC breaker and AC  input on the inverter. Ground from wall socket goes straight to my ground bar in my mini ready DB. Then from the ground bar to the SPD, and from the ground bar to the outlet socket?

Edited March 12, 20233 yr by Wimmas

Good morning Peeps! 

Great job! I want to do exactly what @Wimmas achieved and have a few questions. 

My Mecer Axpert doesn't have an earth wire outof the AC Out side, so how would I do this part? I am attaching a photo of it... It has another earth screw on the body of the Inverter though, not sure if that is the same as one with the AC Out.

Also @Wimmas where did you buy the DC Fuse goodies if you dont mind please?