Electrical Cable Damage
Electric UFH tripping the RCD or not heating? Cable damage is often repairable without replacing the entire system. Learn about diagnosis and repair options.
Safety Warning: Never attempt to bypass an RCD that keeps tripping. This protection device is preventing electric shock. Have the system professionally repaired.
Signs of Cable Damage
System trips RCD immediately
Power trips as soon as the heating is switched on, indicating earth fault.
Partial or no heat output
Some areas heat while others stay cold, or complete heating failure.
Error codes on thermostat
Controller displays cable fault, open circuit, or earth leakage warnings.
Intermittent operation
Heating works sometimes but fails at other times, often temperature-related.
Burning smell from floor
Rare but serious - indicates severe cable damage requiring immediate action.
How We Find The Damage
Thermal Imaging
Infrared camera shows heat pattern. Break in cable visible as temperature change point.
TDR Testing
Time Domain Reflectometer precisely measures distance to cable break.
Resistance Testing
Multimeter checks cable resistance. Open circuit or low reading indicates damage.
Insulation Testing
Megger test checks insulation integrity. Low reading indicates earth fault.
Visual Inspection
Where accessible, checking cable routing at edges and connection points.
Common Causes of Cable Damage
Drilling Through Floor
The most common cause. Drilling or screwing into floor for fixtures damages buried cables.
Solution: Professional cable tracing and repair. Damaged section located with thermal imaging and TDR testing.
Tile Adhesive Damage
Notched trowel or sharp tools damaging cable during tile installation.
Solution: Locate damage point and repair with approved cable repair kit. May require tile removal.
Cable Crushed During Installation
Heavy furniture, tools, or foot traffic crushing cables before screed or tiles set.
Solution: Thermal imaging to locate crushed section. Excavate and repair or replace cable section.
Manufacturing Defect
Rare factory faults in cable insulation or heating element causing premature failure.
Solution: Check if under warranty. Manufacturer may cover repair or replacement costs.
Moisture Ingress
Water penetration damaging cable insulation, often in bathrooms or due to leaks above.
Solution: Locate moisture source. Repair cable damage and waterproof properly.
Cold Tail Connection Failure
The join between heating cable and power cable (cold tail) has failed.
Solution: Often located near thermostat or edge of floor. Remake connection with heat-shrink joints.
Frequently Asked Questions
Need an engineer?
If this guide points to a fault you would rather not tackle yourself, our REFCOM-registered, F-Gas certified engineers cover London and the M25 with 24/7 emergency callout. Engineer time is £120 + VAT per hour with a written quote before any chargeable parts are fitted. Start with the relevant service below, or contact us for a site survey.