No supply at a socket-outlet or point
A socket-outlet or point is dead — nothing plugged in works — while other points may be fine. A bread-and-butter 'trace it back' fault.
Safety first
A 'dead' outlet can become live, or have live terminals nearby. Prove dead before working, and prove your tester before and after. Beware a lost neutral making a dead-looking point dangerous.
Isolate, lock out / tag out, and prove dead before working unless a live test is specifically required, authorised, and carried out under proper supervision. Always follow local regulations, your site procedures, and the equipment manufacturer's documentation.
Full detail — causes, the why, and common mistakes.
Likely causes
Ranked from most to least likely.
- 1
Tripped protective device for that circuit
Most likelyThe breaker/RCD for the circuit has tripped or is off, killing the point.
- 2
Open connection upstream (loose terminal)
#2A loose or broken connection at an upstream point breaks supply to everything beyond it.
- 3
Faulty outlet itself
#3The socket/point has an internal fault or a loose terminal.
- 4
Switch/control upstream off
Least likelyA switch, isolator, or control upstream is off, removing supply.
Reports are saved on this device to reflect what you actually find.
Testing sequence
Work through one test at a time. Expected reading and what each result means.
Check the circuit's protective device is on and hasn't tripped; verify supply at the board for that circuit.
Protective device on and supply present at the board.
Supply leaves the board — trace toward the dead point.
Tripped/off device — restore (and find why if it tripped).
View all expected readings at once
Fault-finding flowchart
The same logic as a decision tree.
- 1start
No supply at point
→ step 2 - 2decision
Is the protective device on and supply present at the board?
Yes→ step 3No→ step 4 - 3decision
Tracing along, does supply reach the outlet?
Yes→ step 5No→ step 6 - 4result
Restore the tripped/off device (find why if it tripped).
- 5result
Supply reaches it — the outlet itself is faulty; repair/replace.
- 6result
Supply lost upstream — repair the open connection at that point.
Common mistakes apprentices make
- Not proving the tester before and after (false 'dead' readings).
- Replacing the outlet before tracing where supply is actually lost.
- Forgetting an upstream switch/isolator that's off.
- Missing a lost neutral that makes a 'dead' point hazardous.
When to stop & escalate
If a protective device trips again when restored, find the fault before re-energising. Tracing within fixed wiring should be done by a competent person following safe isolation.
If you're past your competence, authorisation, or the safe limits of the job — stop and hand it on. There's no fault worth getting hurt over.
Related faults
No control voltage in the panel
Nothing in the control circuit will operate — contactors won't pull in, indicators are dead, the PLC may be off. The control voltage that should be there simply isn't.
Loose connection overheating (discolouration / smell)
A terminal or connection is overheating — discoloured insulation, a burning smell, or heat you can feel — a common cause of nuisance faults and a real fire risk.
Lost or high-resistance neutral
Strange symptoms across a circuit or installation — voltages going high and low on different loads, flickering, equipment damage — pointing to a lost or high-resistance neutral.
Learn the theory
How the gear and circuits behind this fault actually work.