Skip to main content
The Kent M1 has two protective-earth points and both are mandatory. This page covers both PE connections, the backup-port earth rule, and residual-current protection.
For trained/authorized installers only. Earthing errors on this platform cause shock risk and backup failure — not just alarms.

​
Before you start

  • Earthing is done before PV, battery or AC wiring.
  • Earth pit measured and photographed per Earthing & Protection. [KNB-VAL-14 — measure and record; escalate poor soil before energising]

​
Dual PE — never only one

Kent M1 dual protective-earth points — both must be connected — figure KNB-M1-CR-04

  1. System ground in the AC output connector — the PE position of the GRID connector.
  2. Chassis protective earth — the case terminal, fixed with an M4×10 screw at 1.2 N·m.
Connect both. Connecting only one is forbidden by the source manual. Use 10 mm² outdoor single-core copper, and paint the chassis earth terminal after fitting for corrosion resistance. With multiple inverters, every unit is earthed reliably.

​
Backup-port PE

The BACKUP port PE must be grounded, or backup will not operate in a grid failure. This is the single most expensive earth wire to forget — the customer discovers it during their first power cut.

​
Residual-current protection

  • The inverter has built-in residual-current detection and disconnects from the grid when leakage exceeds its threshold.
  • External RCDs are supported: grid side 100–300 mA (recommended), backup side 30 mA.
Pending Kent validation — do not configure in the field. [KNB-VAL-04] Written confirmation of the backup N-E bond-relay behaviour and the approved RCD scheme is under way. Until published here: follow the Kent N-E test in the commissioning checklist and never improvise an external N-E bond.
The Advanced menu contains an NPE Relay Check and an NPE voltage protection threshold — evidence of internal N-E supervision. Leave both at factory state unless a Kent parameter sheet instructs otherwise.

​
Common mistakes

  • Landing one PE point and calling it done — dual PE is a hard rule here.
  • Backup PE left floating because “backup worked fine on grid” — it fails exactly when needed.
  • Improvised N-E bonding in the backup panel to stop RCD trips. [KNB-VAL-04]

​
When to escalate