[brtkdotse]

I’m planning for solar cells and looked into the possibility of running my house as a micro grid (ie disconnect it from the main grid) in case of a prolonged power outage. Turns out that unless you redneck engineer it, running your house without a main grid to synchronize to is very costly - among other things you need to supply your own grid grounding and that could easily run into the high €x000.

[pulse7]

In Europe (EU) every house needs own grounding. You are not allowed to ground on main grid's ground. We have three cables: 1) power 2) zero (=main grid's grounding) 3) own grounding. Only old installations are allowed to connect grounding to zero which is called something like "zeroing".

[cillian64]

In the UK, which was until very recently in the EU, most modern (last 20-30 years) houses have what’s called Protective Multiple Earthing where the house earth is just connected to the incoming neutral and there’s no earth spike at the house. Then the power company earth-bonds at the substation and several points between the substation and houses.

[michaelt]

Don't most UK houses also have earth bonded to all the water and gas pipes in the house?

There may be no earth spike, but if earth connects to a copper pipe going into the ground, you'd expect them to be at the same potential.

[jon_adler]

I believe metal pipe bonding is a building control requirement however many new builds use predominantly plastic pipe work. The requirement is to protect the occupant against touching live metal pipe work, not to earth the house.

[yrro]

Gas pipes can't be plastic!

[kube-system]

Here in the US, I have three wires from the utility: phase 1, phase 2, and neutral. I also have two copper ground rods that are 3-4 meters in length, which are connected to the utility neutral.

[AdrianB1]

At the first electrical panel in many cases the grid's neutral is connected to the house grounding, this is done in new houses in my country as standard.

[GoOnThenDoTell]

> you need to supply your own grid grounding

What does this mean? My naive reading would presume a stake in the ground?

[korlja]

Stake in the ground, as the sister post said, non-corroding, in the simplest case.

But there is more to it: The stake has to have permanent contact to some electrically conductive layer in the ground, so you need to take geology and local climate into account. In central europe, with generally wet climate, you just need to reach the year-long stable, frost-free, local water table at a depth of (usually) between 1m and 10m. If you cannot reach sufficient depth, don't know the required depth, a simple stake isn't going to cut it. Because in case of an electrical fault, the grounding has to withstand and dissipate in the order of a few hundred Ampere. To achieve that you then shallowly bury lines of non-corroding material in a grid, or bury a grounding net something like 1 to 2m deep over an area of 100m^2 to 10000m^2.

If you are on sandy or rocky ground, permafrost, arid climate and no handy body of water is nearby for grounding, you need to have a far larger grounding net or use conductivity-enhancing methods like permanent watering, adding salts or carbon to the soil or replacing it outright with something more conductive. In all, very expensive.

And as for large installations, you just measure the soil conductivity, calculate the necessary grounding current and scale up the aforementioned methods.

[rainbowzootsuit]

This must be a European design. In the USA, governed by NFPA 70 - The National Electric Code, the ground rod's purpose is to establish the ground voltage reference to reference the electrical systems of a building to it and to dissipate any charge buildup on the circuits.

The ground rod is not there to carry current to interrupt a fault to "protective earth" - the green or green/yellow. The circuit breaker interrupts a short as you bring the protective earth wire back to the main disconnect of a building where it bonds to the neutral wire.

If a fault occurs, an unregulated amount of current flows on the protective earth wire to the breaker panel and a circuit breaker interrupts the circuit.

[magicalhippo]

I'm no expert, but here in Norway we predominantly have IT systems[1], though new installations are mainly TN.

In the IT systems, the protective earth is not bonded to the neutral. Thus in case of a fault, the protective earth should be low impedance to ground so that the circuit breakers trip. At least that's my understanding.

[1]: https://aktif.net/en/types-of-earthing-systems/#IT_System

[rainbowzootsuit]

Thanks for the link. I don't know all the symbology there so it will take some reading up.

[taneq]

Technical nitpick, if it detects earth leakage and trips based on that, it's an RCD, not just a circuit breaker. Otherwise yeah, there's different approaches to earthing - in Australia for domestic stuff we have mandatory RCDs which work as you describe above, but then also in industrial/mining settings we have the big green/yellow cables which will directly sink current (potentially hundreds of amps) to ground, hopefully stopping you from getting bitten.

[rainbowzootsuit]

A thermal breaker won't trip on leakage current or arc faults either. I was trying to describe the classic "dead short" that will trip a thermal circuit breaker or fuse without the circuitry for arc or leakage detection.

[donkeyd]

Interesting. The receding ground water level in the Netherlands could possibly impact our electrical infrastructure on a local level then, right?

[dtech]

Ground water isn't really receding, it's just pumped to a low level to benefit agriculture at early spring, which then fucks everyone up if the spring and/or summer is dry.

[taneq]

Usually you can just tie it to an outside copper plumbing pipe, it's metal and makes good contact with your local ground.

Disclaimer: Not intended in any way as professional electrical advice yada yada. Just what I've read.

(Also all sorts of weirdness can take place around grid earth vs. local earth, eg. during thunderstorms. Earthing is its own entire engineering discipline. :S )

[mellavora]

a stake which doesn't corrode.

For fun, put a nail in dirt. See how long it lasts.

[dmoy]

Depends on how much electricity is involved. Might require more than a simple stake

[pyinstallwoes]

What’s more ? Curious what it takes for large setups.

[harveywi]

Proof of stake.

[AdrianB1]

You need to put as much as needed to achieve 4 Ohm to ground or less. This can be up to ~ 10 stakes at a couple of meter interval, it depends a lot on the soil type.

[thesmok]

For individual homes, it often takes three stakes, each several meters long (deep), placed in a triangular config, connected above ground.

[durnygbur]

A big ass steel anchor damn deep in the ground!

[andreareina]

You also need a transfer switch to make sure you're disconnected from the grid otherwise you're going to be feeding power back into lines that are supposed to be dead.