Zaptec Go (UK 7kW open PEN fault version) comes with integrated PEN fault protection as standard. It automatically disconnects your vehicle from the power supply if it detects a fault in the UK’s PME (Protective Multiple Earth) system. This keeps every installation safe and fully compliant with UK wiring regulations (BS 7671:2018 Amendment 1:2020, clause 722.411.4.1 (iv)).

• An independent test report is available here.
• The integrated PEN fault protection cannot be configured or disabled.
• Zaptec Go (UK 7kW open PEN fault version) is identified by the "ZGBxxxxxx" serial number. 
• It has three connections: Live, Neutral, and Earth (PE).

Why is PEN fault protection necessary

• In the UK, all outdoor EV chargers connected to a PME (Protective Multiple Earth) supply must have PEN fault protection by law, as set out in IET wiring regulation 722.411.4.1. 
• Many UK power supplies combine earth and neutral into one PEN conductor. Normally, safe, but if the PEN conductor becomes disconnected (“open PEN”), it can create a dangerous situation: if someone touches something connected to the PEN (like an EV) and something at true earth (like a metal fence), standard RCDs won’t protect you.
• To protect against this, you must either provide a dedicated earth (TT or TN-S system in good condition) or use a charger with PEN fault protection that disconnects all conductors if a fault is detected. If there is any doubt, then PEN fault protection must be fitted.
   

How does it work?

1. Constant monitoring: Zaptec Go checks the voltage between the line and neutral at all times. 
2. Fault detected: 
   • If the voltage rises above 253 V or drops below 207 V for more than five seconds:
     • Live, neutral, and earth connections to the vehicle are disconnected.
     • The charger displays a red light, and charging stops instantly.
3. Automatic reset:
   • Once voltage is normal for 30 seconds:
     • If not charging, the charger returns to ready mode (white light).
     • If charging, it resumes automatically (blue pulsing light) up to ten times before locking out. To reset this lockout state, disconnect the charging cable. The charger will then return to normal operation once it has detected normal voltage for 30 seconds.
     • If the fault repeats, the charger locks out for safety. To reset, unplug and reconnect the cable.
4. Notification: This message will also be shown in the Advanced settings screen of the relevant charger in the Zaptec App.
   
   

What to do if a PEN fault is detected

• Stop charging. A detected PEN fault means that an abnormal supply voltage has been detected that is outside of the statutory requirements. This is a potential safety hazard.
• Contact the Distribution Network Operator (DNO) by calling 105 to report the issue.
• The DNO should then investigate the reason for the abnormal supply voltage and make repairs, if necessary. Additional diagnostic information is available from the charger to help with any investigation. This information can be requested by contacting Zaptec support. 

Updated 07 October 2025 11:34