Understanding Earthing Arrangements - TNCS, TT, TNS

Understanding the earthing system used in electrical installations is essential. Joe Hammond's video provides a detailed explanation of the different earthing arrangements commonly used in UK electricity supply systems. TNCS, TT, TNS

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00:00 Earthing Arrangements
01:00 What types of earthing systems are used?
01:26 TNCS
02:30 TNS
02:50 Top tip from Joe!
03:30 TT
04:10 Challenges of TT Systems
04:40 Earth fault loop impedance - Appendix 4
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[seanpassant]

Joe, this is a really fantastic video, simple, intelligent and well presented. It also has a huge impact on the type of SPD that is installed so I have shared this with our own apprentice to help him understand. Thank you so much.

[ifell]

First video I've watched in ages at normal speed. That means it's great quality with a lot of info!

[andrewsinkoom]

I really love the explanations you gave in the video, I would love to undergo apprenticeship in your noble company. I am Inkoom from Ghana - West African.

[andrewrussack]

In Australia, pretty much all LV installations are TN-C-S AND with a local earth rod connected to the local earth AND the incoming neutral, locally referred to as multiple earthed neutral (MEN, voiced as ‘em-ee-en’). In some areas, the high voltage ‘neutral’ is common with the LV neutral, so common MEN (CMEN).

[jackl]

an American electrician here, it is so different from what we do in the US we usually Bond the equipment ground in the neutral at first means disconnect and then ground rod placed

[auzzierocks]

Here in Australia we have the ground stake at your house, a water bond and an earth-neutral bond at your home fuse board

[kittsdiy]

4:25 funny.. all consumer house here in Belgium are TT .. with eart rod or earthing loop in foundations ( resistance has to below 30 ohm ). Never get a PE from the grid. TN-C i see a lot in factorys 3 lives and 1 PEN conductor ( with thier own high volage transormer cabine ) then we a lot convert them to TN-C-S .. PEN -> PE & Neutral .. if we need 230V .

[petermikus]

In my country TNC was often used some years ago apparently. Which is just Line, earth and neutral combined (PEN). Often you would connect the earth notmaly and then take a cable from there to neutral connection (on outlets for example.

[ElliottVeares]

How about IT (Isolated Terra) systems, which I believe are or were common in places like hospitals?

[senaldeva]

On a TT system, what if you install an earth stake directly connected to the N coming from the supply. And have a separate earth stake for ground within the premises ? Wont that be better for the RCD trip times ?

(Assume the supply transformer is far away from the premises)

[picobyte]

In our swamp called 'the Netherlands' TT works best.
Only on some sand grounds here during hot summers some older sub-standard groundrods fail their resistance.

[joegolden]

Hi, I have a TT system in my house. I'm putting a 10 sq swa cable to a shed and fitting a separate earth rod at that end for fuse board. How can I protect this cable against fault damage in the ground as the earthwill not be connected off swa at shed. 😊

[jjrufilanchas]

I have a couple of questions... What you mean (4min05s) that current "takes some time" through the earth 🤔? No no. And why do you say TT systems are becoming less common.. are you sure? Not in Europe. It is a long engineering discussion if TT systems are cheaper, and more secure than any other schema, but let me just say that it is (at least) daredevil to say the opposite. In any case thank you and good video.

[joopterwijn]

When you have a earth rod, next to the home, and supply power to sheaf, workshop, outbuilding etc is it good practice (and allowed) to add earth rods at each remote building?

[vui]

very nice sharing bro! Thank you very much!

[ld-dmaker]

while good for explaining, i believe the part of the "ground fault making a loop back to the line and going into the protective device" part to be inaccurate. firstly RCD devices operate on the imbalance of the two incoming wires, if your fault sinks current to ground, it doesn't "come back" trough the neutral, thus trips. i really don't know what you're on about with it "going back up into the line", you draw current from the line and sink it to ground, that's what trips a fuse or protective device. any voltages on the neutral line will sink directly into the ground stake at the transformer, not go back up. in that regard TT and TNS/TN-C-S systems perform nearly the same, there isn't any "delay" as it sinks to ground either way, the only benefit i can see is that having a main grounding spike means it's probably much better looked after

[clevelandburnabypowell]

Hi Joe, my background is is in maritime engineering where generally we don't have earthing systems but have earth fault detection instead. Anyway my question - we have a TNCS installation and have had a home battery installed. In the event of a grid power supply failure the house is disconnected from the grid (including earth loop) and the battery continues to supply two circuits. The battery has a earth spike connection so I guess that in the event of a power failure we switch from being a TNCS system to a TT system. How can I find out if the earth spike (one meter) has a sufficiently low resistance to activate the safety devices. The house is built on sand and I am concerned that in dry conditions the resistance to true earth will be high.

[willrussell]

Awesome content, regular watcher & subscriber for years. Have you considered doing a video on DC SPD’s ? The regs (or lack thereof) surrounding them & practical applications.

[lukejay]

Based on the animation, can a TT system be converted to TNCS by joining the Neutral and Earth at the incomer?
I assume not but I'm curious!

[giz]

Earthing Arrangements for mobile or transportable units with or with out the uses of a earth electrode?