Electrical protection Switch, Rcd, Elcb - What's It All About?

The Rcd electrical protection switch. It's precisely an Elcb! I'm a humble electrician working in Fremantle, Western Australia and I wanted to write a small report about electrical protection switches. They used to be called Earth Leakage Circuit Breakers or Elcb for short. Elcb better describes what they do but these days where I'm from a protection switch must be referred to officially as an Rcd which means Residual Current Device. The Rcd is designed to immediately cut off the electricity when it detects a particular value of fault current, normally around 30 milliamps 'leaking to earth'. In other words, going somewhere where it's not supposed to instead of straight through the electrical circuit.

Back in the early 80's I installed one of these things in a fuse box for the very first time with my chain smoking boss looking over my shoulder. It was on a big flash home in Toorak, a nice leafy suburb in Melbourne and I remember thinking how good it would be if every person had one of these things but they were daunting, huge and expensive. Like "what big teeth you have!"

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This Elcb was the size of a shoe box and the whole purpose of trying to squeeze one of these monsters into an electrical box was so that the clients swimming pool had some form of electrical protection should anyone untoward happen.. Again. As you see it had already happened. The home owners young son received a severe electric shock whilst cleaning the pool out with a leaf scoop which had an aluminium handle. Aluminium is an perfect electrical conductor.

So, yes swimming pools do become live, it's not just a thing you see in the movies as shown in Syriana. The power for this swimming pool like every other pool in Australia in those days had no electrical protection switch installed and the innocent looking blue 24 volt pool light which mounts in the water on the pool wall had become flooded. This flooded light caused the "safety isolating transformer" which sits back amongst all the pool gear next to the chlorinator and pool pump to burn out. This transformer plugs into a 240 volt power outlet and no one had realised that it had so badly blown that its 240 volt windings had shorted across to its 24 volt side sending a full 240 volts straight through to the broken light and level into the pool.

This below ground pool was fiberglass which is an insulator, so anyone who decides to hop in the pool and come into sense with the earth, say by sitting on the edge of the pool with legs dangling in the water and arms extended back on the ground as you do, would have absolutely been electrocuted in an instant. Electricity will take the path of least resistance just like water flowing down a creek. I remember the boys father commented to me that his son's life was saved only because he was dressed and wearing shoes at the time. Who knows.

What I do know is in 2011 I'm now specialising in installing protection switches (Rcd's) and even as I write it was only last week that I fitted 2 on a home with a swimming pool that had never had an Rcd fitted before and there are many more like them - possible death traps that is.

SafetySwitch electrical services is my business which I've been running for 11 years and I'm busy fitting Rcd's all over the city where I live. It's nice to know your probably going to be responsible for salvage someone's life one day as the law of averages go and the government in the state where I live in Western Australia has ultimately made it mandatory to have least 2 of these protection devices fitted to every home.

It's so hard for me to dream habitancy not having an Rcd protection switch fitted and I'm enduringly astounded by the amount of habitancy I come across who still don't know about these things. Never heard of them. A bit like talking to kids these days about the Apollo Program, only this isn't rocket science!

Rcd's are now fitted in homes all over the advanced world although Australia was a bit behind the 8 Ball as some countries had them fitted long before us. Just about all the Rcd's are the same type these days and made to shut off power when 30 milliamps of imbalance is detected but they are also installed in the low 10 milliamp range in places such as surgical / hospital environments and in the higher 100 milliamp range in commercial areas. That 100 milliamps is technically still adequate to electrocute you but it's wise to have that level of protection where otherwise there would be none.

The very first Rcd in commercial use was designed to trip at 250 milliamps and was invented in South Africa as a means of achieving safer electrical installations for their deep, wet secret gold mines. I've worked on a few gold mines myself in Western Australia (we work on a fly in, fly out roster).

By the way, if you have a protection switch make sure you test it every 3 months. A lot of them just seize up as they stay idle for so long, often several years. In fact when we test old Rcd's we often find that they don't work at all. Testing them is a great way to ensure they'll work when they should. Have you go a protection switch?

- Robert Middleton.

Electrical protection Switch, Rcd, Elcb - What's It All About?

SHOCK YOU LIKE AN ELECTRIC EEL