RCD, RCBOs and CBs
RCDs, RCBOs & Circuit Breakers Explained – Electrical Safety for Lewisham Homes
Understanding how your electrical protection devices work is key to keeping your property safe and compliant. At PLS Electrical, we help landlords and homeowners across Chislehurst, Lewisham, Kent, Surrey & Sussex choose the right protection for their circuits.
Here’s a breakdown of how RCDs, RCBOs, and circuit breakers work—and why they matter.
What Is an RCD and How Does It Work?
Residual Current Device (RCD) protects against electric shock and fire caused by earth faults.
- Under normal conditions, current flows evenly through live and neutral wires, creating magnetic fields that cancel each other out.
- If a fault occurs (e.g., electricity flows through a person to earth), the balance is lost.
- The RCD detects this imbalance and instantly disconnects the circuit, preventing harm.
Where RCDs Are Used: Construction sites, outdoor lighting, marinas, medical locations, EV chargers, solar systems, and more.
What Is an RCBO?
RCBO (Residual Current Breaker with Overcurrent protection) combines the functions of an RCD and a circuit breaker.
It protects against:
- Earth faults (like an RCD)
- Overloads and short circuits (like a breaker)
How It Works:
- Magnetic trip: Detects sudden overcurrent and disconnects within 0.1 seconds.
- Thermal trip: Responds to sustained overcurrent by heating a bi-metallic strip, causing disconnection.
Why RCBOs Are Better for Homes:
- They protect individual circuits, so only the faulty circuit trips.
- This avoids the inconvenience of losing power to multiple rooms.
What Does a CB (Circuit Breaker) Do?
Circuit Breaker protects against overloads and short circuits.
- Under normal conditions, contacts stay closed and carry current.
- During a fault, the magnetic field from high current triggers a spring-loaded mechanism, instantly tripping the breaker.
- Thermal trips respond more slowly, disconnecting after sustained overcurrent.
Which Should You Use?
- RCDs: Cost-effective for grouped circuits but can cause widespread power loss during faults.
- RCBOs: Ideal for residential use—more precise, safer, and less disruptive.
- Circuit breakers: Essential for overload and short-circuit protection, often used alongside RCDs or RCBOs.
Need Help Choosing the Right Protection?
PLS Electrical offers expert advice and installation of RCDs, RCBOs, and consumer unit upgrades across Chrislehurst and surrounding areas.
📍 Serving Chislehurst, Lewisham, Kent, Surrey & Sussex 📞 02036330009 🌐 www.plselectrical.co.uk 📧 info@plselectrical.co.uk