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DB requirements


Elbow

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Hi guys,

Sale of my new place has gone through and I’m starting some initial tidying up.

We are going to smooth over all the stipple plaster :-o - so before doing that it makes sense to install additional power sockets etc.

While I’m at it I thought I’d fit the DB(s) ready for a PV install to come.

I’m going to end up with some loads on the output of the inverter, some staying on the grid.

 Looking at the pics it seems like people add a separate DB.

My existing board is in a kitchen cupboard with the prepaid meter next to it.  The other side of the wall is in a passage.  So what I thought to do is to mount two new DB boxes in the passage, with access between them and the existing board.  One will be the new “fed by the inverter” board, the other can maybe replace or supplement the old board.

in the grid board I will need a breaker to feed to the inverter mains input, and another to feed the “bypass” side of the changeover switch in the “fed by the inverter” board.

Then in the inverter board I’m going to need said changeover switch, a breaker and/or earth leakage, and the breakers going to the loads.

Does this seem reasonable?

I also sometime want to fit some “home control” stuff - I have a esp8266 controlled relay board etc - what are the rules for such things? Can I fit inside the DB or do I need another box adjacent?

Appreciate your advice!

Elbow

 

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2 hours ago, Elbow said:

 Looking at the pics it seems like people add a separate DB.

Mostly because the existing DBs in houses are already so full that you can't fit everything, sometimes because you need to split the house into essential and non-essential circuits, and sometimes because there is a requirement that when you have both UPS-backed and non-backed circuits, there has to be a clear distinction, a kind of air-gap if you will. Some electricians will allow them in the same board, some won't. I cannot tell you where in the regulations that is, but the shear fear I have that I might put grid power onto my inverter output even by accident drove me to make it separate.

2 hours ago, Elbow said:

Can I fit inside the DB or do I need another box adjacent?

Again, I would be too scared of having those things alongside one another, and the potential for a bridge to put high voltage onto wires that "run off elsewhere" (rumour has it that flight TWA 800 exploded because high voltage got onto low-voltage wires feeding level sensors in a fuel tank), but there are these really nice DIN-mount enclosures that can help you mount such things inside a DB, and that I feel okay with (just incorporate a good isolated power supply).

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  • 2 weeks later...

 

Well, in related news.  Here is the DB in my new place.  The house was built in 1973 - clearly you can see the original board, and then some additions made later.

To my suprise this apparently qualifies for a COC.

Earth-leakage wasn’t required until 1974.

Looking at the old part, at the left is a main switch (double pole) and then a separate 60A trip. Next comes a 45A trip for the stove,  Note the use of 3-phase cable with two conductors in parallel to carry the current.  Next comes a 30A “mix” circuit for plugs and lights.  Next is a geyser circuit (30A) and then 3 10A light circuits.,

In the new part is a circuit going to the pool sub-DB and two plug circuits - the kitchen and some additional plugs elsewhere.

So for me I don’t feel happy with the lack of earth-leakage for some of the plugs in the house, and the jumble of what is fed from where.I suspect that downstream its probably going to be “interesting” figuring out how the spurs route to plugs and lights.

So I would like to pull most or all of the old breakers and switch in the 18mm versions as at the right - much more trips can be accomodated, I can feed all the plug circuits from the earth leakage, get rid of the “mix” circuit and use more sensible tripping amperages for the stove and geyser.

Which will also make room for the circuit feeding a solar sub-board.

I’d be interested in comments from y’all!?

Thanks
Elbow

 

 

 

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Looking at your DB I notice that you have the same (possible) problem that I have. Our house , also a old farmhouse (the bricks is still those old clay halve backed ones), got a very similar DB size and it seems like pipes were very expensive those days. I also have only 4 pipes coming into the box in my case they resorted to having "mini" DB's in the ceiling running the wires all over the place. I am redoing the whole house wiring but as the brick's arent user friendly I am going surface mount. Will post some pick when I start.

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So I redid the board - turned out that almost every power socket and several lights ran off one circuit.

so now I have 5 plug circuits, air cons on their own breakers, and proper e/l on all the plugs.

and the board is so much neater. :)

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And I have a CoC worth something!

Elbow

 

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Yep, it’s a shame it goes that way, but it was practical since the incoming supply wires were too short to reach to the top left.

The space next to the main switch is there for the feed to the coming inverter board.

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