Across the world power utility companies provides us electricity in different formats but fundamentally they are all the same.
From the turbine driven alternators comes three lines with high voltage, which will first be stepped up using transformers, enabling efficient transporting over kilometers, then dropped via transformers to lower to usable/safer levels of voltages .e.g. 33000Volts dropped to 11000V then 6600V and finally to 400V – these voltages are measured between the lines (in the electrical world they are referred to as phases…and there starts another story for another day!).
Now as all countries are different each might come up with their own version of a system but at the end of the day it will all come down to this:-
After the last “delivery” transformer it is a rule that the neutral (AND REMEMBER THIS WORD) point where the phases are connected together be earthed.
What on earth is this?…that’s just it…some genius came up with the idea that the earth is a common denominator everywhere, why should it not be for electricity too! (but as with everything here are special exceptions)
Challenge: If you are an electrician…do you know where this topic is going?
In other words why don’t we use the landmass as a return conductor (Ok don’t get lost here! – Remember for electricity to flow one needs to to have a complete circle of conductance/circuit…we normally say the one coming back is this return conductor.)
Why should anyone care about this?
Well electricity would have been lethal every-time you touched an unearthed appliance, if it was not for this genius.
So at the moment one side of every single phase load (Sorry, I have to put this here otherwise the comments gets flooded because of only this omittance) like lights, heaters whatever in your house/office is bound – quite literally to ground – so it makes it much, much safer for all.
Ps1: Why ground? Because you are always grounded – it is the potential difference in electricity that will kill you!
Ps2: If you know any better I beg for your patience because, yes I know there are three phase applications that does not use this grounding…but please realise it is in the spirit of making a point here.
Ps3: Take a wild guess what is the voltage if measured between any line and earth?
and if you half that?
And so it is that we have derived the household voltage we are all so familiar with 230V(2) and half that 110V – just to reiterate – different countries have different systems but ultimately it all comes down to the same.
But because the earth mass has a high resistance we help it by connecting a wire parallel to the earth and the method normally entails “bonding” it in strategic places. This ensures safety across the complete reticulation.
Question: Would one want this earth conductor to be part of the current carrying circuit…will we not loose the objective of it serving a purpose of safety?
Now, remember I asked to remember the return conductor called neutral!
Solution: Run another wire in parallel with the earth mass…and lets call it: The neutral wire...and the purpose of this neutral is solely to serve as a return path for the main electrical circuit. It is also bonded to earth but we recognise it to be part of the power circuit so as not to loose the safety component of earthing. What is even more brilliant is the fact that we can now manage the main circuit separately and accurately with all kinds of safety devices.
Ok, I am sure this background information will suffice for the topic of circuit breakers…lets continue.
When Mr. Edison and and Mr. Tesla had their life changing or more like civilisation changing disagreement, circuit breakers did not exist yet, making Edison’s point extremely valid, because sooner or later, everything would have burnt down under electrical fault conditions and humans would have died like flies…apocalyptic end of the world stuff.
Every time it rains and it gets wet in the wrong places…big explosions from the electrical suppliers side.
Every time a cable decides to short to ground or other lines…brilliant lightning bolts and flames, just like in the movies.
Edison said it and it is as true as day…AC voltages is dangerous, especially at the potentials humans are using it…but here comes the saviour…Mr. Circuit-breaker! We install it in the live conductor and whenever an over current or abnormality occurs…it trips.
And there we have it…our life saver…Mr. Circuit breaker makes it possible for us to safely, under all circumstances of possible failure, route electricity all around the world right to your house so we can be warm and cuddly in winter with the electric blanket and all.
But Mr. Circuit breaker has a cousin…this cousin apparently was invented in South Africa…and this, after a lady was electrocuted at one of the goldmines there…and this cousin probably saves countless lives every second around the world…yes every second…yes around the world.
The South African know this boytjie as Mr. Earth leakage…apparently the Europeans NOW calls it a Residual Current Device and the Americans know it as a Ground Fault Current Interrupter(GFCI)…Really?
Ok, In reality they all operate and install differently but that is a story for another time!
For instance:- Earth leakage works on differential current monitoring and the RCD actually measures any the leakage current. gs
And there I digress again…sorry man, I just could not leave out the cousin…next when we continue we will cover selecting a correct circuit breaker from a sales point of view or same for an electrician from a technical point of view.
Ok so this is the low down on circuit breakers::
If the electrical reticulation starts from thousands of volts (kilovolts) and is dropped to safer levels for our usage then one can appreciate that the lines (conductors) will also become smaller as we approach the lower and safer levels.
To cover the different areas of distribution effectively the electrical fraternity is split in distinct groups/classes – high voltage(gs?), medium voltage(gs?) and low voltage(1000V and less).
This low voltage is our baby. The one that makes our every day, around the globe, and we will always find a code of rules and regulations to ensure public safety. Of course the others also have rules and regulations but they are for the big and clever boys…so lets leave that to their own fun and games.
Low Voltage Electrical Rules and Regulations: One day when I am big I would like to make a links available to all these codes for anyone, anywhere to read and assess in order to ensure the electrical installation around them is safe. I really believe it should be freely available to anyone, electrician or not, so one has the best chance of understanding the dangers of electricity.
Conclusion: One can appreciate that, when a wire gets smaller it can carry less electricity…therefore the global rule: Whenever a conductor is downsized or a component within that circuit is lower rated then a protection device must be installed to ensure if more current is passed then the circuit can handle the electrical supply must be isolated – and the circuit breaker does this job.
DONE…now you have the gist of it.
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