An RCD (residual current device) works by monitoring the wiring in a building for leaking electrical current. RCDs, also called safety switches, are only able to be installed by a licensed and fully-insured electrician. The reason you want to ensure your electrician is licensed and insured is that if an RCD Safety Switch fails, and the electrician is at fault, you’re covered. If the electrician is not licensed or insured, you may not be covered by your own insurance and that’s costly. DCN Electrical will happily show you copies of our insurances and licenses.

What does an RCD do?

The RCD continuously measures the amount of current passing through a wire in one direction, and again through a different wire in the opposite direction.

If it detects a difference greater than 300 mA (milliamps), or less in some cases, it breaks the circuit and stops the flow of electricity.

If the current is “missing”, it means there is a leak somewhere in the wiring installation. If this current leaks through a person’s body, it could lead to potentially fatal electrocution.

Residual current devices protect people.

What is the difference between a fuse, circuit breaker and RCD/safety switch?

how does an RCD Safety Switch workA circuit breaker is a more modern method. It has an internal switch that will trip during an overload or short circuit. This prevents the current from going any farther and damaging equipment or in the case of your home, anything plugged into the outlets, like a refrigerator or a computer. Once the danger of the surge has passed, the circuit breaker can be reset.

A fuse, on the other hand, isn’t used in new construction. You can find them in older homes and buildings. A fuse is either AC (high voltage) or DC (low voltage). It acts as a breaker, but instead of resetting it, you manually have to replace it since it has a metal strip or a strand that sparks during an overload or short circuit. That strip melts and the fuse burns out. The fuse is just less efficient and has to be replaced while a circuit breaker switch can be reset easily.

You can read more about the differences here.

Why do I need an RCD or safety switch if I have circuit breakers?

A safety switch protects YOU the person or any other person/s that may come into contact with any faulty electrical system and/or appliances.

Circuit breakers are great for protecting the cabling in your install. They don’t protect the person. Circuit breakers should be rated to the cable size in the installation. We can check this for you too.

What if my RCD isn’t working?

It’s important that you make sure that your RCD is working properly. Before we do any work on your premises, we will test your RCD for all of our safety. Like anything, RCD safety switches wear with time and slow down with age but milliseconds can save a life. It’s important to keep your RCD in good working order and if you’re in doubt it’s best to replace your RCD. Contact DCN Electrical on 0404 863 975 for a free quote.