- EV charging
- EV charger
PEN Fault
Zaptec PEN fault on EV charger: abnormal supply voltage cut
Risk level
High
Professional inspection is recommended.
Urgency
High
Quick answer
On the Zaptec Go UK 7 kW, a PEN fault (red light and an app error) means the built-in protection cut charging because of an abnormal supply voltage. Stop charging and report it to the network operator; Zaptec treats it as a potential safety hazard.
Safety first
Stop and check this first
- With an open PEN conductor, touching the car and an earthed metal object at the same time can be dangerous: do not work on the installation and leave it to the network operator and electrician.
Safe checks you can perform
- Check the red light and the Advanced settings message
- Confirm you have the UK version with PEN protection
- Unplug the cable to clear a lockout
Leave these tasks to a qualified professional
- Do not attempt this professional task: Supply investigation by the network operator
- Do not attempt this professional task: Earthing arrangement review by an electrician
- Do not attempt this professional task: Charger diagnostic data via Zaptec support
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Supply investigation by the network operator
What they doThe distribution network operator investigates why the voltage left its limits and repairs the supply if needed; in the UK Zaptec says to call 105.
They must show youthe cause found on the service cable or network and the action taken.
In writingthe incident reference, the cause and the repair carried out.
Earthing arrangement review by an electrician
What they doA qualified electrician or certified installer verifies that the earthing arrangement and installation comply with BS 7671 and local regulations.
They must show youthe earth loop impedance reading and the line to neutral voltage at the connection point.
In writingthe confirmed earthing system, the measured values and any correction.
Charger diagnostic data via Zaptec support
What they doThe installer requests from Zaptec the additional diagnostic information the charger stores to support the investigation.
They must show youthe event log with dates, times and voltages of the cut.
In writingthe log received and the charger firmware version.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Check the red light and the Advanced settings message
- Who:
- you, from outside the charger and in the Zaptec app.
- How:
- see whether the Zaptec Go shows a red light and open the charger's Advanced settings screen in the app, where Zaptec says this message is also displayed.
- Result that matters:
- confirming that the cut comes from the PEN protection rather than another alert.
- If the app shows the PEN fault:
- stop charging and report it to the network operator as Zaptec asks.
- If the app shows a different error:
- look up that specific message before acting.
- Evidence to keep:
- a screenshot of the app alert and a photo of the charger light.
Evidence: Integrated PEN fault protection (Zaptec Go UK 7kW)
Confirm you have the UK version with PEN protection
- Who:
- you, reading the outside label or the app.
- How:
- find the charger serial number: Zaptec says the UK 7 kW version with integrated PEN protection starts with ZGB, for example ZGB123456.
- Result that matters:
- knowing whether this Zaptec article applies to your specific charger.
- If the number starts with ZGB:
- follow the PEN fault steps in this article.
- If the number is different:
- the integrated PEN protection described here does not apply; ask your installer.
- Evidence to keep:
- a photo of the serial number taken without opening the unit.
Evidence: Integrated PEN fault protection (Zaptec Go UK 7kW)
Unplug the cable to clear a lockout
- Who:
- you, only if the cable shows no damage.
- How:
- if the charger locked out after several cuts, disconnect the charging cable; Zaptec explains it returns to normal once it detects correct voltage for 30 seconds.
- Result that matters:
- checking whether the voltage is back to normal without overriding any protection.
- If the white ready light returns:
- still report the recorded cut to the network operator.
- If it turns red again:
- stop charging and wait for the network operator to check the supply.
- Evidence to keep:
- the time you unplugged and the light colour afterwards.
Evidence: Integrated PEN fault protection (Zaptec Go UK 7kW)
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- EV charging
- Brand
- Zaptec
- Product type
- EV charger
Known code variants
- zappi error 29 PEN
- zappi fallo PEN
- zappi fault code 29
- zappi open PEN fault
- zappi PEN Fault
- Zaptec fallo PEN
- Zaptec Go abnormal supply voltage
- Zaptec Go fallo de PEN
- Zaptec Go PEN fault detected
- Zaptec Go protección PEN tensión anómala
- Zaptec Go UK luz roja PEN
- Zaptec Go UK red light PEN
- Zaptec neutro abierto
- Zaptec open PEN fault
- Zaptec PEN fault protection tripped
What it means
Zaptec explains that the Zaptec Go UK 7 kW (serial number starting ZGB) monitors the voltage between line and neutral at all times. If it rises above 253 V or drops below 207 V for more than five seconds, it disconnects live, neutral and earth from the car, shows a red light and stops charging. Once voltage is normal for 30 seconds it resets, resuming up to ten times before locking out. The protection cannot be disabled. The alert alone never proves the charger is faulty, and other Zaptec Go versions or firmware may act differently.
Warnings and stop conditions
- Highsource verified
With an open PEN conductor, touching the car and an earthed metal object at the same time can be dangerous: do not work on the installation and leave it to the network operator and electrician.
Evidence: Integrated PEN fault protection (Zaptec Go UK 7kW)
Symptoms and causes
Probable causes · in order
- Open PEN conductor on a PME supplyPossible
Zaptec notes that many UK supplies combine earth and neutral in one PEN conductor and that, if it disconnects, a dangerous situation arises that standard RCDs do not cover.
Evidence: Integrated PEN fault protection (Zaptec Go UK 7kW)
- Supply voltage outside statutory limitsCommon
The charger trips when it measures more than 253 V or less than 207 V between line and neutral for over five seconds, which Zaptec places outside statutory requirements.
Evidence: Integrated PEN fault protection (Zaptec Go UK 7kW)
- Repeated fault leaving the unit locked outPossible
If the cut keeps recurring, the Zaptec Go locks out for safety after up to ten automatic resumes and only recovers once the cable is unplugged and reconnected.
Evidence: Integrated PEN fault protection (Zaptec Go UK 7kW)
Virtual technician
Does PEN Fault still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
Integrated PEN fault protection (Zaptec Go UK 7kW)
Zaptec · 2026 · official_doc
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