> ## Documentation Index
> Fetch the complete documentation index at: https://learning.kent.co.in/llms.txt
> Use this file to discover all available pages before exploring further.

# Earthing and Protection for Kent New Energy Systems

> PE first-on last-off, Kent M1 dual PE, Kent G3 grounding, PV frame earthing, earth pit measurement KNB-VAL-14, Type II SPDs, and RCD selection guidance.

Good earthing is the difference between protection devices that work and expensive decoration. This page is the overview — exact conductor sizes and terminal torques live on each platform's installation pages.

<Warning>
  **For trained/authorized installers only.** Earthing errors on a Kent hybrid system can prevent backup operation, defeat all overcurrent and surge protection, and create an undetected live-chassis hazard. Do not cut corners on this work.
</Warning>

## Protective earth (PE) — first on, last off

Connect the inverter's PE terminal **before any AC or DC wiring**. Remove it last when you de-install. This is a universal electrical rule; on a hybrid it matters more because the enclosure sits between three live sources.

<CardGroup cols={2}>
  <Card title="Kent M1 — Dual PE is mandatory" icon="plug-circle-exclamation">
    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 also be grounded** — backup operation will not work in a grid failure without it.
  </Card>

  <Card title="Kent G3 — External grounding conductor" icon="plug">
    Connect the external grounding conductor and the heat-sink grounding terminal per the manual figure on the Kent G3 installation page. Copper conductor is recommended. Follow the platform page for cable size.
  </Card>
</CardGroup>

<Info>
  **PV module frames** are earthed to the array earth per IS 3043 practice. The PV+ and PV− conductors on these transformerless platforms are **not** earthed. The platform installation pages carry the specifics for each platform.
</Info>

## The earth pit

Measure pit resistance with a proper earth tester at every site. Photograph the reading. Log it on the commissioning checklist. Poor or unmeasurable earth is a **stop work** condition — fix it before energizing.

<Warning>
  **Pending Kent validation.** \[KNB-VAL-14]
  Kent's published earth-resistance limit is under confirmation. Until published here: measure and photograph the reading at every site, do not attribute any specific ohm figure to the manual, and escalate poor-soil or high-resistance sites to Kent before energizing.
</Warning>

## Surge protection (SPD)

Kent requires external **Type II SPDs on both the AC and DC sides** on Indian sites, regardless of any built-in surge protection in the inverter. The surge and lightning environment on Indian sites demands it.

* Fit AC-side SPDs at the distribution board.
* Fit DC-side SPDs in line with the PV string wiring.
* Check SPD health indicator flags at every service visit — a sacrificed SPD that has not been replaced is an unprotected system.

<Note>
  SPD wiring positions and earth connection points are specified on the platform installation pages. An SPD with a high-impedance earth connection provides no protection — land its earth on a verified, low-impedance earthing point.
</Note>

## RCDs

RCD selection is platform-specific and ties into the backup N-E behaviour that is pending OEM confirmation on both platforms.

<Accordion title="Kent M1 RCD guidance">
  Residual-current monitoring is built into the Kent M1. External **Type A** RCDs are supported on the grid side — 100–300 mA is recommended. The backup-side RCD scheme is tied to the N-E behaviour under validation. See \[KNB-VAL-04] on the [Electrical Basics](/safety/electrical-basics) page.
</Accordion>

<Accordion title="Kent G3 RCD guidance">
  RCD selection and the backup-side scheme follow the Kent G3 installation page. Until the N-E validation is resolved \[KNB-VAL-04], do not add external N-E bonds to manage RCD behaviour in backup mode — record the N-E voltage on the commissioning checklist for Kent review.
</Accordion>

## Common mistakes

<Accordion title="Connecting only one Kent M1 PE point">
  Kent M1 has two mandatory PE connections: the AC-connector system ground and the chassis earth terminal. Connecting only one leaves the other path open. The most common consequence is backup mode failing silently in a grid outage — when you need it most.
</Accordion>

<Accordion title="Landing the SPD earth on a paint-covered bolt">
  An SPD with a paint-covered or corroded earth connection cannot discharge a surge impulse quickly enough to protect the equipment. The earth landing point must be clean metal, confirmed low-impedance by measurement.
</Accordion>

<Accordion title="Skipping the earth pit measurement">
  "The building has earthing" is not a documented earth-resistance reading. Measure, photograph, and log the reading at every site. You are protecting yourself, the customer, and the warranty as much as you are protecting the equipment.
</Accordion>

## Related pages

* [Electrical Basics for Hybrids](/safety/electrical-basics)
* [Site Photo Checklist](/environment/site-photo-checklist)
* [Safety First](/safety/safety-first)
* [Isolation & Shutdown](/safety/isolation-and-shutdown)