ApprenticeLow risk

USB power point not charging devices

A GPO with built-in USB ports won't charge (or charges very slowly) while the normal sockets work — usually the USB module or a device/cable mismatch.

Start fault-finding

Safety first

Isolate before removing the outlet. The mains sockets working proves the point is live.

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. 1

    Device/cable not compatible or faulty

    Most likely

    A faulty cable or a device needing more current/a protocol the outlet doesn't support.

  2. 2

    USB module failed

    #2

    The built-in USB converter has failed while the mains sockets still work.

  3. 3

    Output below device's needs

    Least likely

    Older USB GPOs deliver limited current; a power-hungry device charges slowly or not at all.

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.

Test 1 of 2
1

Try a known-good cable and a different device on the USB port.

Expected reading

It charges a known-good device with a good cable.

If it passes

It was the device/cable — done.

If it fails

Still nothing — suspect the USB module or its output rating.

Often leads toPower point (GPO) completely deadDouble power point — one side works, one doesn't
View all expected readings at once
1. Try a known-good cable and a different device on the USB port.
It charges a known-good device with a good cable.
2. Confirm the mains sockets on the same GPO still work, isolating the fault to the USB module.
Mains sockets fine; USB dead.

Fault-finding flowchart

The same logic as a decision tree.

  1. 1
    start

    USB GPO not charging

    → step 2
  2. 2
    decision

    Does a known-good cable + device charge?

    Yes→ step 3No→ step 4
  3. 3
    result

    It was the device/cable — done.

  4. 4
    decision

    Do the mains sockets on the same GPO still work?

    Yes→ step 5No→ step 6
  5. 5
    result

    USB module failed — replace the outlet (or use a plug charger).

  6. 6
    result

    Mains also dead — treat as dead GPO.

Common mistakes apprentices make

  • Blaming the outlet when it's a faulty cable.
  • Expecting fast charging from an older low-output USB GPO.
  • Not confirming the mains sockets still work.
  • Opening it live because 'it's only USB'.

When to stop & escalate

Replacing the GPO is licensed electrical work. A failed USB module means the whole outlet is replaced.

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

Power points & circuits

Power point (GPO) completely dead

Nothing plugged into a power point works, while other outlets are fine. A classic trace-it-back fault on a single GPO or the run feeding it.

4 causes3 test steps
ApprenticeMedium risk
Power points & circuits

Double power point — one side works, one doesn't

On a double GPO, one socket works and the other is dead — usually an internal fault in the outlet or a loose link between the two sockets.

3 causes2 test steps
ApprenticeMedium risk
Power points & circuits

Half the power points in the house not working

A group of outlets across several rooms is dead together while lights and other GPOs work — points at one power circuit's protection or a shared upstream fault.

4 causes3 test steps
ApprenticeMedium risk