15years ago my TAFE lecture did not explain it like this at all. Such a shame this part of an apprentice the lecture brushed over this swiftly. Your explanation shows how important it is and all under 30mins which was also very clear and precise. Thanks 🙏
I'm doing a generator connection to my house, and as I'm sure you know the neutral now also goes through the changeover switch (been a few years since I've done one). The question is, do I need a earth-neutral connection at the generator inlet as I'll obviously be losing the men connection when switched over to the generator?
very handy video thanks! Would be great if you could use a chopstick or something instead of the ruler though because sometimes it's not clear what your pointing to
Thank you. Very easy to understand info. But i have a further question. In an off grid system (solar with lightning protection+inverter+generator) where does this link go? Do they all run to the same earth? Is there a way to separate the earths so that lightning or static electricity does not upset the rcd function? Is that even an issue? There is a real lack of info on this subject. Maybe im just looking in the wrong place?
Should the MEN link be thick, least resistance or thinner making a higher resistance? I'm thinking thicker so the current can pass through quicker and the resistance of the other metals in the housing will allow for that 5 or 10 ms delay. Am I correct?
that depends on on the wiring rules. A dummy value is having it the same csa as the neutral conductor, but there are variations to consider in varying the size. theres also a rule stating a conductive enclosure needs bonding equivalent to that of the neutral conductor. Imagine seeing a 16mm2 bond on a domestic board wtf hahah. But like i said there are variations to factor in that can either increase that size or decrease.
There's a few things I'm missing here. Why doesnt a little/all current flow from the neutral bar through MEN link to ground? I was under the impression this path is super low resistance. Also where does current go once going to the mass of the earth? Does this diagram show it going back up the power pole?
The reason the Neutral and Earth wires are connected together via the MEN link is : 1) To make the sure the Neutral is at the same Potential as the Earth Stake in the Physical Earth (0 Volts). 2) To create a path of low resistance for Fault current via the Neutral to the Transformer so a large enough current will flow to trip the Circuit breaker. In normal operations little to no current flows through the Physical Earth as the resistance of the Physical Earth is very high.
Traditional earthing via an earth stake is there to protect the electrical installation (wiring etc) from lightning, not for protecting appliances and people. If protecting appliances and people is all that is required then a path to earth isn’t strictly necessary, although it does provide some redundancy in case of high resistance or open circuit on the neutral. Electric current will always try and return to where it came from, if it came from the pole transformer it will try and return to the pole transformer (through the neutral wire or the earth stake if there isn’t a path back through the neutral). If it came from the ground (lightning) it will try and return to the ground.
