THE EARTHING SYSTEM
The most important part of you electrical system is the earthing system as this is what helps protect you and your family from electrical shock. The earthing system connects all your appliance with conductive parts (ie. stove, washing machine, fridge…) so that if there was an active fault in the appliance the circuit protection would trip and the appliance would not become live. There are many parts to the earthing system from the earth electrode (pictured) outside your home to the connection on the appliance, some of these parts are inside the main switchboard that includes a connection to the main natural as well as other places. Your main earth electrode should not be a piece of pipe it should be a copper plated steal rod like the pitcher with a tag on it.
Are you experiencing electric shocks from metal parts in your home (ie. stove, fridge, water tap…)? This could be a sign that the neutral connection has come to fault and potentially dangerous voltages are leaking back onto the earthing system (since the neutral and earth are connected). Your lights could be flickering or your appliances behaving strangely as they are all receiving odd voltages.
Is your earth completely surrounded by concrete? This could potentially become a shock risk as the resistance of the earthing system to earth has become of a high resistance. The current flows in the path of least resistance. This means that the earthing electrode has a resist so high that it no longer operates as it is designed to and the current does not pass to earth. Have you had work done on your home like external walls being re-sheeted ? if so check your earth has not been disconnected as we have seen this to be the case on some jobs.
Burnt off neutral.
The next part of your electrical safety is the circuit protection device (ie. circuit breaker of fuse). If your home still has fuses (pictured) we recommend replacing them with circuit breakers and/or circuit breaker RCD combination protection as fuses is technology that is over a century old and at least 30 years out of date. This is where we find most power faults in older installations.
Plug in Circuit breakers are not an acceptable replacement solution as, like fuses, anyone can put any size breaker in and overload the circuit which in turn can cause fire. For example a large 32A circuit breaker (stove size) into a 6A wiring situation (lighting circuit).
This type of protection should be replaced immediately as it is out of date and can be dangerous.
To the left is circuit breakers that are used today (varying in appearance based on brand). But wait, that’s not all. After the fuse was removed circuit breaker protection was installed to improve electrical safety. Some years later it became law that your power AND LIGHTING circuits have to be protected by RCD (Residual-Current Devices).
I can not say enough about the need to replace the old fuses with residual-current circuit breaker (rccb) as these new devices are real life savers and the old fuses are very bad protection against electrical shook, and i wood say that 50% of the faults i deal with are related to fuses, normally in the way of the wire burning off the back of them.
The next is the Residual-Current Device (RCD) that is probably the most important thing you can have put on your homes electrical system. In fact, in Australia, it is law to have an RCD on all your power and lighting circuits, this includes 3 phase outlets.
You can test these with the test Button on the device, but we recommend that if you have just bought your home that you have a qualified electrician to test the operating of an RCD with a proper Residual-Current Device tester. The test Button only tells you that they will trip but not if they are doing their job in the required tripping time.
Lastly, in years gone past many electrician install one RCD to protect the entire building. We recommend against this and it is frowned upon today because if you have a fault on 1 circuit you could lose supply to your whole home. Instead we use residual-current circuit breaker (RCCB) on each circuit, this device is a Residual-Current Device and a circuit breaker in one.
4 POLL RCD 2 POLL RCD RCCB
ISOLATION LINK / MAINS PROTECTION
All switchboard should have mains protection and any new switchboard or switchboard that have had metering work modifications must have mains protection. The most common form of mains protection is a CB on the penal near the meters that is sealed by Ergon and has a sticker ( contact an electrical contractor if this circuit breaker is in the tripped (0) position), the other way of doing this is to have a meter isolation link and a CB as the main switch, this in most cases is not recommended as there will be more then 1 main switch and the rating on any one might be too low and cause nuisance tripping.
Parker’s Electrical NQ recommends that everyone that has old fuses in there switchboard inquire about a upgrade immediately as they are over 30 years out of date and can be a fire danger. We recommend that you have all your power and lighting circuits on a residual-current circuit breaker (RCCB), have mains protection, and you have the whole installation checked every 2 years and as soon as possible after a cyclone when your house has had any damage.
The reason for this recommendation is that RCD’s can go faulty, earths can break, neutrals can also break off at the pole or mains box. The electrician should check you’re earthing system including fans and lights, your active and neutral connections, all the connections in the switchboard, a RCD test with results, and a fault loop impedance test. The resulting tests should then be supplied to you in the format of a report with required changes and recommendations that has been found.
This article is the opinion of Parker’s Electrical NQand is only a guideline, for more information contact your Electrical Contractor.
© 2016 Parker’s Electrical NQ. You have the right to use any part of this article as long as you credit it to Parker’s Electrical NQ and link back to this article using this link ELECTRICAL SAFETY IN YOUR HOME BY PARKER’S ELECTRICAL NQ