Why RCD Protection and Proper Wiring Matter
Outdoor lighting installations can enhance the beauty of any property, but they also come with unique challenges. During an EICR (Electrical Installation Condition Report), low insulation resistance was identified in a garden lighting circuit without RCD protection. This poses potential safety hazards that need rectification, including installing RCD protection and ensuring the wiring is resistant to water ingress.
Table of contents
1. What is Low Insulation Resistance?
Low insulation resistance occurs when there is a decrease in the effectiveness of the electrical insulation, leading to the possibility of electrical faults such as short circuits or electric shocks. It is usually caused by damage to the wiring or moisture ingress. This is particularly common in outdoor circuits exposed to weather elements, such as garden lights.
During an EICR, low insulation resistance can indicate that the wiring is no longer safe, requiring immediate attention to prevent risks to both the occupants and the property.

2. Why RCD Protection is Essential for Outdoor Circuits
RCD (Residual Current Device) protection is crucial for any outdoor electrical installation. An RCD continuously monitors the electric current flowing through a circuit and disconnects the supply if it detects a fault, such as an imbalance caused by water ingress or insulation failure.
In this case, the garden lighting circuit lacked RCD protection, which is why it wasn’t tripping despite low insulation resistance being detected. Without RCD protection, any fault in the circuit could lead to electric shocks or damage to the electrical system. Installing an RCD for this circuit is necessary to ensure safety.
3. The Challenges of Wiring Garden Lights
Outdoor installations are notoriously difficult to wire for long-term durability. Exposure to rain, moisture, and fluctuating temperatures can compromise the effectiveness of even the best electrical installations. Water ingress is one of the main culprits for the premature failure of garden lighting systems. Once moisture finds its way into a junction box or cable, it can lead to insulation breakdown, short circuits, and corrosion.
4. How to Protect Garden Lighting Installations
The key to ensuring that garden lights remain functional for years is preventing water ingress. Properly sealed junction boxes, filled with special gel compounds, can provide a long-term solution. Gel-filled junction boxes create an airtight, waterproof seal around connections, protecting them from the elements.
If you are wiring or maintaining garden lights, it is essential to use high-quality materials designed specifically for outdoor environments. Regular junction boxes won’t suffice—specialized products that prevent moisture from reaching the connections are a must.

5. Recommended Products to Ensure Long-Lasting Garden Lighting
To make sure your garden lighting installation remains reliable for years, it’s essential to use the right products. Here are some highly recommended options that will help protect your system from water ingress and other environmental factors:
- Wiska Gel: A high-performance gel that creates a water-resistant barrier in junction boxes. This gel is essential for ensuring that moisture doesn’t compromise your outdoor lighting installation.
- Wiska LEDJOY IP68 Gel Filled Junction Device: This product is designed to provide full protection for outdoor connections. With an IP68 rating, it’s perfect for use in challenging weather conditions and ensures a long-lasting seal around your garden lights.
- Wiska Combi Boxes: A versatile, watertight solution for outdoor electrical connections. These combi boxes, when used with Wiska Gel, offer an additional layer of protection to safeguard your outdoor lighting installation. Their robust design makes them ideal for garden lights exposed to the elements.
- Wago 207 Series Gel Boxes: Known for their quick and easy installation, these gel-filled boxes ensure long-term reliability by preventing water ingress and maintaining a secure connection for garden lighting systems.
By using these high-quality products, you can ensure that your garden lighting installation remains functional and free from faults for many years. For all of these products, visit the Gel and Compound section at Electrical4Less.
If you’re looking to purchase these items locally, be sure to stop by the Fulham Electrical Trade Counter at Electrical4Less. Located at 9 Seagrave Road, SW6 1RP, it’s your go-to source for top-quality electrical supplies, expert advice, and competitive prices.
6. FAQs: Garden Lighting and RCD Protection
A: If your garden lighting circuit has RCD protection, it could be tripping due to moisture ingress or a fault in the wiring. Ensure all junction boxes are sealed with gel to prevent water from affecting the circuit.
A: Yes, the 18th Edition Wiring Regulations (BS 7671) require RCD protection for all circuits that are likely to be used outdoors or in damp environments, including garden lights.
A: It’s a good idea to have outdoor circuits, including garden lights, checked as part of your routine EICR, or at least once every 3-5 years. Regular inspections can help identify issues like low insulation resistance before they become serious.
A: If your lights are flickering, tripping the RCD, or failing to turn on, these are signs that moisture might have entered the system or there could be a fault in the wiring. Addressing the issue early can prevent further damage.
A: Using gel-filled junction boxes like the Wiska LEDJOY IP68 or Wago 207 Series Gel Boxes is the best way to protect your connections from water ingress. Additionally, ensure that all cables are properly insulated and protected from the elements.
Get in Touch with Fulham Electrician
For installation services, you can rely on Fulham Electrician – MGB Electrical Solutions Ltd, operated by Mirek, a trusted, well-established, and fully qualified electrician. With credentials such as being a JIB Gold Card holder, NAPIT member, and Checkatrade member, Mirek provides safe and professional electrical services, including fault finding, EICR reports, and consumer unit replacements