On this page
- What you can safely check before calling an electrician
- Signs that mean switch off and call
- How an electrician finds the fault
- Fault finding is not the same as an EICR
- Landlords: a fault on the report starts a 28-day clock
- After the fault is found: does the repair need sign-off?
- What electrical fault finding costs
The short version
- Look for scorch marks, hot sockets and damaged leads, but leave every cover on.
- A burn mark, heat or a burning smell means switching that circuit off before anything else.
- An electrician narrows the fault from board to circuit to one item, testing a circuit proven dead.
- Most fault repairs are not notifiable; a new circuit, consumer unit or bathroom-zone change is.
- Our minor fault finding starts from £100 including VAT, and the repair is quoted before work starts.
Electrical fault finding means tracing a fault step by step, from the consumer unit to one circuit and then to the socket, cable, fitting or appliance causing it. You can make safe visual checks and note which switch dropped. The instrument tests belong to an electrician. Our guide price for minor fault finding starts from £100, including VAT.
What you can safely check before calling an electrician
A few minutes of looking gives the electrician a head start, and sometimes finds the cause outright. None of these checks means taking a cover off or touching wiring.
- Plugs: a cracked, melted or discoloured casing, or coloured wires showing where the cable enters
- Cables and leads: cuts, crushed sections or joints wrapped in tape
- Sockets and switches: burn marks, or a faceplate that feels warm
- Overloading: adaptors plugged into adaptors, or heaters on extension leads
- The consumer unit: which switch is down, and which rooms have lost power
If a switch in the board keeps dropping, our guide to a fuse box that keeps tripping walks through the unplug-and-reset checks. Unplug any appliance that looks damaged and leave it unplugged.
Signs that mean switch off and call
Some symptoms can wait for a booked visit. Others mean the circuit or appliance should be switched off first.
| Sign | What it usually points to | What to do now |
|---|---|---|
| Scorch or burn marks on a socket or plug | Overheating at a connection | Stop using it and switch the circuit off |
| A socket or plug that feels hot | A loose connection or an overload | Unplug, stop using the socket |
| Buzzing or crackling | Arcing at a loose or damaged connection | Switch off that circuit and book a visit |
| A burning or fishy smell | Plastic overheating at a socket or fitting | Switch off and find where it comes from |
| Lights that flicker or bulbs that keep blowing | Often a loose connection | Book an electrician |
| An RCD that keeps tripping | Current leaking from an appliance or the wiring | Stop resetting it and book fault finding |
Our electricians in London trace faults like these for homeowners and landlords. Call 07727 619854 and describe what you have seen.
How an electrician finds the fault
Fault finding is a process of elimination. Each step rules out most of the installation, so the tests end up on the one part that is wrong.
- Ask and look. What happened, when it started, and what the consumer unit shows.
- Prove it dead. The circuit is isolated and checked with a proper voltage indicator, itself checked before and after.
- Find the circuit. Tests on each circuit show which one carries the fault.
- Split the circuit. Disconnecting it at a socket or junction halves the search, and the test is repeated.
- Test each item. Sockets, fittings, cable runs and appliances are checked until one fails.
- Repair and retest. After the fix, the circuit is tested again before it goes back into use.
The tests behind the diagnosis
These are the same tests the wiring regulations, BS 7671, set for checking an installation. In fault finding they are aimed at one circuit at a time.
| Test | What it finds |
|---|---|
| Continuity | A broken or loose conductor, including the earth |
| Insulation resistance | Insulation that has broken down, tested at 500 V DC with a minimum of 1 MΩ |
| Earth fault loop impedance | Whether a fault would clear quickly enough to cut the supply |
| RCD operation | Whether the RCD trips fast enough when current leaks to earth |
Faults that come and go
An intermittent fault is the slowest kind to find, because it may not be there when the tests run. For leakage, the electrician isolates circuits one at a time and measures each appliance with a leakage clamp meter. Telling us when it happens, such as after rain or with one appliance on, saves time.
Fault finding is not the same as an EICR
An electrical inspection, the EICR, records the condition of the whole installation. If a reading fails, the report records it. Tracing why it failed is separate fault-finding work, not part of the inspection.
If a report you already hold carries an FI code, it asks for further investigation. Our guide to what the EICR codes mean explains each one.
Landlords: a fault on the report starts a 28-day clock
In England, the electrical safety regulations for rented homes set firm deadlines once an inspection report calls for investigation or repair:
- the work must be done within 28 days, or sooner if the report says so
- written confirmation that it is done goes to the tenant and the council within 28 days of finishing, with the council's copy including the report
- if the investigation turns up more work, the same steps apply again
Our landlord EICR service covers the inspection, the fault finding and the remedial work, so one firm signs it all off.
After the fault is found: does the repair need sign-off?
Most fault repairs are not notifiable under Part P of the Building Regulations. Replacing a damaged socket, repairing a connection or renewing a damaged cable on a single circuit are repairs, and they still have to meet BS 7671.
The repair is notifiable in England if it involves:
- a new circuit
- a replacement consumer unit
- adding to or altering a circuit in the zones around a bath or shower
A kitchen is not on that list, whatever some websites say. If the board itself turns out to be the problem, our guide to old fuse boxes explains the options.
What electrical fault finding costs
Our guide prices include VAT. The repair is quoted once the cause is found, and you decide before any work starts.
| Job | Guide price (VAT included) |
|---|---|
| Fault finding (minor) | from £100, typically £100–£150 |
| Diagnosing a tripping fuse box | from £90, typically £90–£150 |
To book, call 07727 619854 or request a quote online. Our London electricians cover homes and rented properties across the city.
Frequently asked questions
Not safely. Safety guidance advises against multimeters and non-contact voltage pens for proving a circuit dead, because the wrong setting or a false reading can leave you touching live parts. Stick to looking at plugs, leads and sockets, unplugging appliances and noting which switch dropped.
Lights that flicker, or bulbs that keep blowing, often point to a loose connection in a fitting, switch or the circuit. A loose connection can overheat, so have an electrician check it rather than living with it.
A socket or plug should never feel hot. Heat usually means a loose connection or too much load, such as a heater on an extension lead. Unplug everything from it, stop using it and book an electrician.
Usually not. Repairs and like-for-like replacements are not notifiable in England. The work is notifiable if the fix means a new circuit, a new consumer unit, or changes to a circuit in the zones around a bath or shower.