How to Fit a Fused Spur from an Existing Fused Spur
Introduction
A fused spur is an important part of many electrical installations, allowing power to be extended safely to appliances or additional circuits. Adding a new fused spur from an existing fused spur can be a practical solution in both homes and workplaces, but it requires careful planning and strict compliance with UK safety regulations.
This guide explains the basic process, key safety points, and best practices. For full compliance and peace of mind, working with a qualified london electrician is strongly recommended.
Electrical Installation and Maintenance in London
What Is a Fused Spur?
A fused spur (also called a fused connection unit or FCU) is a connection point that supplies power through a built-in fuse. The fuse protects both the wiring and the connected appliance from overload.
Fused spurs are commonly used for fixed appliances such as boilers, extractor fans, and lighting circuits. Extending from an existing fused spur allows you to add another supply point without connecting directly to the main ring circuit, helping to maintain safety and compliance with BS 7671 wiring regulations.
Step-by-Step Installation
1. Turn Off the Power
Switch off the power at the consumer unit and confirm the circuit is dead using a voltage tester. If possible, prevent accidental re-energisation.
2. Check the Existing Fused Spur
Confirm the fuse rating and ensure the existing spur can handle the additional load. A 13A fused spur may supply only limited additional load, so calculations are essential. If unsure, consult an electrician.
3. Plan the Cable Route
Decide on a safe route for the new cable from the existing fused spur to the new location. Avoid water pipes, heat sources, and areas outside recognised safe zones.
4. Fit the Mounting Box
Install the new mounting box securely at the chosen position, either flush-mounted or surface-mounted depending on the wall type.
5. Run the Cable
Run a length of 2.5mm² twin and earth cable between the two fused spurs. Strip the cable ends and prepare the conductors (live, neutral, and earth).
6. Connect the Existing Fused Spur
Open the existing fused spur and connect the new cable to the load terminals:
- Live (brown) to L
- Neutral (blue) to N
- Earth (green/yellow) to E
Ensure all terminals are tight and no bare copper is visible.
7. Wire the New Fused Spur
At the new fused spur, connect the incoming cable to the supply terminals:
- Brown to L
- Blue to N
- Green/yellow to E
Insert the correct fuse (for example, 3A for lighting or 13A for heavier appliances) and fix the faceplate.
8. Test the Installation
Restore power and test the new fused spur with a voltage tester. Check that the connected appliance works correctly.
9. Certification
Electrical work must meet Part P requirements. Testing and certification by a competent electrician may be required to ensure compliance.
Safety Considerations
- Always isolate and test the circuit before working
- Confirm load capacity before adding a second spur
- Protect cables using suitable clips or conduit
- Follow BS 7671 and Part P regulations
- Seek professional help if you are unsure
Why Choose a Professional?
Although experienced DIY users may understand the process, mistakes can lead to overheating, electric shock, or non-compliant installations. A qualified electrician in london will ensure the work is safe, tested, and certified.
Professional installation also protects your home insurance and ensures long-term reliability.
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