As technology advances, so do the safety standards in our homes, particularly in the realm of electrical systems. In the UK, the installation of Residual Current Devices (RCDs) and Residual Current Breaker with Overcurrent protection (RCBO) is becoming increasingly common to enhance the safety of electrical distribution boards. While these upgrades are essential for modern safety standards, they can pose challenges, especially when dealing with older properties. This article delves into the issues that can arise when upgrading the electrical distribution board with RCD and RCBO protection in older UK homes.

1. Age of Cables

One of the primary challenges encountered during the upgrade of electrical distribution boards in older properties is the age of the cables. Many older homes were originally wired using cables that may not be compatible with the sensitive tripping mechanisms of RCDs and RCBOs. Over time, insulation on these cables may have deteriorated, leading to potential faults and false tripping, which could be disruptive and unsafe.

The dreaded Green-Goo

“The wet green liquid that you are seeing is the product of a reaction between decomposing plasticiser (a plasticiser is an oily liquid used in the manufacture of PVC compounds) and the copper conductors of PVC cables. It’s better known as cable ‘greening’.
The decomposition of the plasticiser is caused by overheating the PVC compound. It is usually a slow process, but can be accelerated when high temperatures are involved. High temperatures can be caused by external reasons, but overloading and loose connections are two common examples.
Although all cable grades of PVC may look the same, the cheaper grades can be more prone to producing the green goo. The main instances of ‘greening’ cable arose during the 1960’s and 1970’s, although some instances are still seen today. Inferior grades of plasticiser were prone to greening even if the cables were not overheated.”
Source: uk.prysmiangroup.com/media/news/green-goo

2. Inadequate Earth Fault Loop Impedance

An important parameter for the proper functioning of RCDs and RCBOs is the earth fault loop impedance. This value determines how quickly the device can detect a fault and disconnect the circuit. Older properties might have higher loop impedance due to outdated wiring practices, resulting in a slower response time of RCDs and RCBOs. This delay could compromise the level of protection provided against electric shocks or fires.

3. Compatibility and Space Constraints

In older homes, the electrical layout might not have been designed to accommodate the additional space required for modern RCDs and RCBOs. Upgrading the distribution board to fit these devices might necessitate modifications to the existing setup, potentially requiring structural changes or rewiring.

4. Voltage Fluctuations and Sensitivity

RCDs and RCBOs are designed to detect even small imbalances in current flow, which can be advantageous in terms of safety. However, older properties are more prone to voltage fluctuations due to aging infrastructure. This increased sensitivity could lead to nuisance tripping, disrupting power supply unnecessarily and requiring constant attention to reset the devices.

5. Limited Fault Discrimination

RCBOs provide both overcurrent and residual current protection in a single device. However, this can sometimes lead to limitations in terms of fault discrimination. In older homes with complex wiring systems, the presence of multiple devices sharing the same RCBO might hinder pinpointing the exact location of a fault.

6. Cost Implications

Upgrading the electrical distribution board with RCD and RCBO protection in older properties can be costlier than in newer constructions. The need for rewiring, modifications, and potential replacements of cables to meet safety standards can significantly increase project expenses.

Conclusion

While the incorporation of RCDs and RCBOs in electrical distribution boards undoubtedly enhances safety, it's important to recognize the challenges posed by upgrading older UK properties. The age of cables, inadequate loop impedance, compatibility issues, voltage fluctuations, and the intricacies of fault discrimination are all factors that need careful consideration. Prior to initiating an upgrade, homeowners should collaborate with qualified electricians to assess the property's existing electrical infrastructure, address potential issues, and ensure a successful and safe transition to the enhanced protection offered by RCDs and RCBOs.

What are the challenges of upgrading your home electrical distribution boards with RCD & RCBO protection in older UK properties?