Would be good if you could do a video showing in plain English how to test if an exposed conductive part or extraneous conductive part requires bonding. There are figures ranging from 50v/0.03mA = 1666.67 Ohms. 23000 & 26000 Ohms etc.

I'm not sure this does answer the question. Is it really to do with a broken combined neutral-earth on TN-C-S? Surely the point about bonding on a TN-C-S system is that, in the event of a live/line to metal infrastructure fault (gas pipe, plumbing etc.) then the impedance of the bonding must be low enough that it will cause the MCB to trip. If there's a supplier-side break in the combined neutral/earth, then the current flowing through all the active electrical devices will try and flow through the bonding connection to anything connected to earth. However, I'd wager that it not going to be able to carry large amounts of current. Even a metal water or gas pipe (increasingly replaced by plastic in both cases) isn't going to have a low enough impedance to earth to carry tens of amps, and certainly nowhere near the difference between a 10 mm^2 or 6 mm^2 cable. It's likely in the case of a break in the neutral on supply side that the potential of anything bonded to the buildings PME is going to rise to high levels as the earth impedance is going to be in the tens of ohms, even with metal gas and water pipes. Compare that to 10 metres of 6mm^2 cable (about 0.05 ohms). TT is different. It has to be designed with protection to cope that the earth impedance is tens of ohms. It might trip a 6A MCB on a line to earth fault, but that's about it. Consequently, having ridiculously large profile bonding conductors serves little purpose. So, I think that the larger profile bonding conductor on TN-C-S is all about the ability to trip something like a 40A MCB on a line to metal plumbing/gas pipe fault and for that, you need very low bonding resistance. With a TT system, if there's that same fault, there's no way that the resistance to earth of a conducting rod is going to trip that MCB. Even in the best case, it will be lucky if it can carry 10 amps and the difference between 6mm^2 and 10mm^2 binding cable is entirely irrelevant.

To be picky, table 54.8 is based on the size of supply PEN conductor, not neutral conductor (although really just a change of terminology). Also, do the regs stipulate 6mm2 for TT? A MPB conductor can be 6mm2 min. - 25mm2 max., not just 6mm2. The question is though, on TT, why is it 6mm2 min, when the earthing conductor only need be 2.5mmm2 if mechanically protected and 4mm2 if not mech protected? The earthing conductor only needs to be big enough to carry the current that will fire the RCD, and there's no diverted neutral currents for the MPB conductor to carry, so why does the MPB conductor need to be bigger than the EC on TT? Sorry, but the presenter merely repeated what's in the regs, without explaining why it is so. Regarding earthing, it seems the regs are really designed for TN systems, with TT just thrown in the mix as a side issue, and applying TN to TT is good enough.

sorry but that was explained like a polititian, answered without really giving an answer. 😕😉

I leave in Malawi central Africa. Our supply system here ,PEN conductor is grounded along the route but entry to the house ,say single phase ony neutral and phase enter the premises and customer creates earthing by providing an earth electrode. Is this TT or TNCS?

Interesting. Flat clips on a round cable

Please do a full video covering earth neutral bonding on a sun sync inverter giving special attention on the wiring using either contactor or relay .

So basically if the Earth is being used as a phase return, you need to match that size of the incoming Earth/Phase return?

Not only does the bonding conductors have to take the building's load current but also that of other installations connected to the DNOs mains cable downstream of a broken CNE/PEN conductor on the mains cable.

I notice your protective Earth label was missing 👀

More importantly who paints a wall such a bright green 0:57 🤔

got a 125 amp commando socket on a pme, they have a fly up to a marquee the total run is 100m or so my commando socket is about half way. a guy got a whack off a metal case of some stage equipment. I'm thinking its difference in potential i'm thinking of ditching the PME at the commando and TT with 100ma time delayed rcd at the commado socket does that sound right scratching my head ha

Hi , in ring circuit when 2.5 mm2 used and the two ends of each wires of cable connect to 32 amp circuit breaker , I think if this breaker which is single 32 amp replace to (double poles) circuit breaker (MCB) that's rated to 16 amp, so when we have issues in point in cable of the ring circuit or cable have cut in conductors so for that will not make cable get over heated when having load excited 16 amp and the breaker will isolated the current so we will have Warning of fault , this is an opinion because it will reduce a lot of fuses or protection points.

You could have been bit more pragmatic, mr jobsworth

Covering arses and BS🤣🤦‍♂️