Protecting You and Your Home
The purpose of both safety switches (RCDs) and a circuit breaker is protection, but they are not the same thing. This short post is here to help you better understand the safety devices installed in your switchboard. The design of the equipment is to prevent damage to the home and to save lives.
Circuit breakers (CBs) protect the cabling of a circuit from an overload of current. CBs will have a particular current rating, selected depending on the application. When current being drawn through a circuit exceeds the breakers rating, the breaker will trip and power will be cut to that circuit. Most people will have experienced this.
Current creates heat, and too much current means too much heat. Most cables are able to safely handle up to 75 degrees Celsius. When too much current travels though a circuit the cables can quickly generate heat. This can cause insulation to melt and produce arcing between conductors (wires). This is how many electrical fires start and this is what circuit breakers are for, protecting cables and equipment, not lives.
Safety switches (also known as RCDs or residual current devices) are designed to trip under an ‘earth leakage’ situation. The RCD detects the current coming into the circuit and out of the circuit. Under normal circumstances these in-going and out-going currents should be the same, what goes in must come out. When the RCD detects that these currents are not the same it will very quickly cut the power to the circuit, about 30 milliseconds, this means there has been an issue in the circuit.
The main scenario being a person coming in contact with electricity. For instance, when someone comes in contact with a live metal part, some current will run through them. As a result, the current in and out of the circuit is longer equal. The RCD senses this change and cuts the power. Therefore, they are not to protect a circuit from overload but they are to save lives.
We prefer to use RCBOs. They are a combination between a circuit breaker and a safety switch. This makes fault finding much easier and also means that only one circuit is tripped out instead of half the house.
Master Electricians Australia says that 34% of Australian households are not protected by RCDs. Is your house protected by a safety switch? Give us a call on 0458 201 052 or contact us here, we are your first choice electrician in Geelong and surrounding areas.