FAULTNEST ELECTRICAL
Electrical Fault-Finding Guides
Diagnose common electrical problems involving RCDs, circuit breakers, sockets, lighting, switches, lost power and household wiring. Start with the exact symptom, then work through the safest checks first.
Electrical safety comes first
Never remove covers, test exposed conductors or work on live circuits unless you are competent to do so. Isolate the supply and prove dead before touching fixed wiring. Burn marks, heat damage, crackling, repeated tripping or damaged cables should be treated seriously.
Read FaultNest electrical safety guidance →BROWSE ELECTRICAL FAULTS
Choose the type of electrical problem
Open the section that matches the fault, then choose the individual troubleshooting guide.
RCD and circuit breaker faults Tripping, reset problems, overloaded circuits and intermittent faults.
RCD Keeps Tripping
Find appliance, circuit and earth leakage faults.
RCD Won’t Reset
Check downstream faults, neutral-earth problems and failed devices.
RCD Trips Randomly
Diagnose intermittent leakage, moisture and appliance faults.
RCD Trips When an Appliance Is Used
Identify faulty appliances, sockets and circuit issues.
Circuit Breaker Keeps Tripping
Check overload, short circuit and damaged wiring causes.
Circuit Breaker Won’t Reset
Work through load faults, circuit faults and breaker failure.
Main Switch Keeps Tripping
Understand whole-property shutdowns and urgent warning signs.
Consumer Unit Buzzing
Recognise loose connections, overloaded devices and dangerous faults.
Socket and outlet problems Dead sockets, loose fittings, heat damage and power loss.
Socket Not Working
Check supply, spur, circuit and socket faults.
One Socket Not Working
Diagnose isolated socket and connection problems.
Multiple Sockets Not Working
Check ring final circuits, radials, breakers and loose connections.
Socket Switch Not Working
Identify worn switch mechanisms and internal connection faults.
Socket Sparking
Separate normal plug arcing from unsafe socket faults.
Socket Buzzing or Crackling
Recognise loose connections, arcing and heat damage.
Socket Feels Hot
Check excessive load, poor connections and damaged accessories.
Burnt or Discoloured Socket
Assess heat damage and when immediate replacement is required.
Plug Stuck in Socket
Deal safely with overheated pins and damaged shutters.
USB Socket Not Working
Check the USB module, supply and replacement options.
Lighting faults Flickering, dim lights, failed fittings and switch problems.
Light Not Working
Check lamp, fitting, switch, breaker and wiring faults.
Multiple Lights Not Working
Trace circuit, junction and protective device issues.
Light Keeps Flickering
Find lamp, dimmer, driver and loose connection faults.
LED Light Flickering
Check incompatible dimmers, drivers and low-load issues.
Light Is Dim
Identify lamp, voltage, transformer and driver problems.
Light Stays On
Diagnose faulty switches, sensors and wiring errors.
Light Won’t Turn On
Work through common supply and control faults.
Light Switch Not Working
Check worn mechanisms, loose conductors and circuit faults.
Light Switch Buzzing
Recognise dimmer noise, loose connections and unsafe arcing.
Dimmer Switch Not Working
Check lamp compatibility, minimum load and switch failure.
PIR Security Light Not Working
Test sensor settings, daylight controls and supply faults.
Outside Light Not Working
Check water ingress, fittings, sensors and external supplies.
Power loss and supply faults Whole-house outages, partial power loss and intermittent supply problems.
No Power in the House
Separate utility outages from internal electrical faults.
No Power in One Room
Check local circuits, fused spurs and connection faults.
Half the House Has No Power
Diagnose lost circuits, RCD banks and supply issues.
Power Keeps Cutting Out
Find intermittent RCD, overload and supply faults.
Power Goes Off When It Rains
Check outdoor circuits, water ingress and damaged accessories.
Lights Dim When an Appliance Starts
Assess voltage drop, high starting current and connection faults.
Power Surges in the House
Recognise supply instability and protective device issues.
Electricity Meter Has No Display
Check supply loss and when to contact the network operator.
Switches, fused spurs and controls Failed switches, FCUs, timers, thermostats and isolators.
Fused Spur Not Working
Check the fuse, switch, supply and connected load.
Fused Spur Keeps Blowing a Fuse
Identify appliance, cable and load faults.
Isolator Switch Not Working
Check switch failure, supply and downstream problems.
Pull Cord Switch Not Working
Diagnose worn mechanisms and loose ceiling connections.
Timer Switch Not Working
Check programming, power supply and relay failure.
Electric Shower Switch Not Working
Recognise damaged pull switches, heat and supply faults.
Cooker Switch Not Working
Check isolator, circuit and appliance faults.
Fixed appliances and dedicated circuits Electrical supply faults affecting cookers, showers, heaters and extractors.
Electric Oven Has No Power
Check isolators, fuses, circuits and terminal faults.
Electric Hob Has No Power
Trace supply, switch and appliance connection issues.
Electric Shower Has No Power
Check pull switches, breakers, isolators and thermal faults.
Extractor Fan Not Working
Check isolators, timers, humidity controls and motor faults.
Bathroom Fan Keeps Running
Understand timer, humidity and wiring causes.
Electric Heater Not Working
Check supply, thermostats, thermal cut-outs and elements.
Immersion Heater Not Working
Check timers, thermostats, elements and fused supplies.
Doorbell Not Working
Check transformer, button, chime and cable faults.
Outdoor and garden electrical faults External sockets, lights, sheds, garages and water-related faults.
Outside Socket Not Working
Check local RCDs, weather damage and supply faults.
Outside Socket Keeps Tripping
Identify water ingress, cable damage and connected load faults.
Shed Has No Power
Check armoured cable supplies, local boards and protective devices.
Garage Has No Power
Trace submain, RCD and distribution board faults.
Garden Lights Not Working
Check transformers, photocells, joints and water ingress.
Outdoor Electrics Trip in Rain
Locate moisture-related insulation and accessory faults.
Heat, smell and noise warnings Urgent electrical symptoms that should never be ignored.
Burning Smell From Electrics
Find immediate isolation steps and likely sources.
Buzzing Noise From a Wall
Recognise arcing, transformers and concealed electrical faults.
Crackling Noise From Electrics
Understand why crackling often indicates a loose or arcing connection.
Fishy Smell From Electrics
Check overheated plastic, accessories and consumer unit components.
Electrical Switch Feels Hot
Assess load, connection and switch failure risks.
Consumer Unit Feels Hot
Recognise overloaded or loose protective devices.
Sparks From Consumer Unit
Immediate safety action for serious electrical faults.
Electrical testing and fault-finding basics Reference guides that support the troubleshooting pages.
How to Reset an RCD Safely
Correct reset sequence and what repeated tripping means.
How to Find Which Appliance Is Tripping the RCD
Use a safe isolation process to identify the faulty appliance.
How to Check If a Socket Has Power
Safe checks using approved testers and known-good loads.
How to Test a Fuse
Continuity checks, visual inspection and replacement guidance.
How to Identify Circuits in a Consumer Unit
Map circuits carefully without unsafe live work.
Electrical Fault-Finding Tools
Useful testers, meters, insulated tools and safety equipment.
Multimeter Safety for Home Electrical Testing
Understand meter categories, safe ranges and common mistakes.
When to Call an Electrician
Know which symptoms are unsafe or beyond DIY troubleshooting.
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