Protective earth (PE) — first on, last off
- Connect the inverter’s PE before any AC or DC wiring, and remove it last.
- Kent M1 — dual PE is mandatory. Both the AC-connector system ground and the chassis protective-earth point must be connected — never only one. Use 10 mm² outdoor single-core copper and paint-seal the chassis earth terminal after fitting. The Backup-port PE must be grounded or backup will not operate in a grid failure.
- Kent G3 — connect the external grounding conductor and the heat-sink grounding terminal per the manual figure; copper conductor recommended.
- PV module frames are earthed to the array earth per IS 3043 practice; PV+/PV− conductors are not earthed on these transformerless platforms — platform pages carry the specifics.
System earthing overview — figure KNB-SVG-12; site example KNB-PH-05
The earth pit
Measure pit resistance with a proper earth tester at every site, photograph the reading, and log it on the commissioning checklist. Poor or unmeasurable earth = stop and fix before energizing.Surge protection (SPD)
Kent requires external Type II SPDs on both the AC and DC sides on Indian sites regardless of built-in protection — the surge and lightning profile demands it. Check SPD health flags at every service visit.RCDs
- Kent M1: residual-current monitoring is built in; external Type A RCDs are supported — grid side 100-300 mA recommended.
- Kent G3: RCD selection and the backup-side scheme follow the platform installation page.
- The approved backup-side RCD scheme for both platforms is tied to the N-E behaviour item — see the validation block on Electrical Basics [KNB-VAL-04].
Common mistakes
- Connecting one Kent M1 PE point and calling it done — both are mandatory, and backup will not run in an outage without the Backup-port PE.
- Landing the SPD earth on a paint-covered bracket bolt — SPDs need a real, low-impedance earth.
- Skipping the pit measurement because “the building has earthing” — measure, photograph, log.