This article is going to look at the pros and cons of RCBOs and RCDs so you can decide which one to use.
An RCBO is a residual current circuit breaker with overcurrent protection. An RCD is a residual current device. On the surface, they sound identical. Let’s look at them in more detail.
An RCBO is designed to ensure that electrical circuits operate safely. Whenever an imbalance in current is detected, it triggers disconnection. They protect against overcurrent and earth leakage.
Overcurrent can be an overload or a short circuit. In an overload, the circuit is trying to provide power to too many electrical devices. This causes the amount of electricity in the cables to exceed the capacity of those cables to carry that electrical load. In a short circuit, the circuit doesn’t have enough resistance and the current is too high for the components. Both of these situations commonly cause overheating and electrical fires so protection from them is critical.
Earth leakage happens when a circuit has been accidentally broken, such as due to a wiring mistake or an accident like cutting through a lawn mower power cable with a garden spade. If the supply of electricity remains unbroken, it can lead to a potentially deadly electric shock.
An RCD is a safety device to protect electric circuits. It automatically turns off the electricity if there is a fault. An RCD provides continuous monitoring of the electricity in a circuit. It does this by monitoring the current passing through a wire in both directions. When there is no difference between these currents, the circuit is working correctly.
When an RCD detects that the electricity is not flowing correctly, such as if someone has touched a live part, it cuts power to that circuit. It can sense this because in this case, there will be a difference between the current passing in the line and the current passing through neutral. The sensitivity of the RCD varies depending on the exact make/model you buy. Thus, an RCD prevents fire and electric shocks.
As you can see, there appears to be a lot of overlap between RCBOs and RCDs. But while their basic function is to protect people and property from faulty circuits, they have some differences, too. RCBOs have an integrated switch. The RCBOs can do everything an RCD does as well as protecting the circuit from overload and short circuit events.
The decision about whether an RCD or RCBO is best for you depends on your overall design and the amount of money you can spend. RCBOs do more, but that comes with a higher price tag, and no one wants to spend money unnecessarily. A setup of several RCBOs will mean when one detects a fault, only that one RCBO will trip, which is convenient for the rest of the distribution. RCDs will trip the whole circuit, which is less convenient, but they do cost less. There is no disadvantage to investing in either an RCD or an RCBO.
At iLECSYS, we stock a range of RCBOs and RCDs.
Read more: Residual Current Devices
Read more: RCBOs