Floating Neutral and 380 V at the Outlet: The Fatal Hybrid Install Error in Georgia

Classic commissioning ending: fried electronics on site and owner claims for tens of thousands of lari. In typical tear-downs the root cause is not factory defect — it is incorrect neutral switching and the wrong bypass module.

Physics: how a 220 V outlet becomes ~380 V

In a three-phase TN system, phase-to-neutral stays near 220 V (Georgia’s standard) while the neutral point is solidly bonded to earth.

NORMAL (solid neutral):
Phase A (kettle 2 kW) ──── 220 V ────┐
Phase B (router 50 W) ──── 220 V ────┼── [common N] → PE / earth
Phase C (fridge) ───────── 220 V ────┘

BROKEN / OPEN N (floating neutral):
Phase A ───[kettle 2 kW]───┐
                           ├─ N drifts → light phase sees ~380 V
Phase B ───[TV / board 50 W]┘

When the installer opens neutral between grid in (Grid N) and backup out (Load N), or uses a cheap unsynchronised 4-pole breaker:

1. The inverter’s neutral point floats.
2. Phase loads are never balanced (boiler on one phase, Wi‑Fi / boiler board on another).
3. Heavy phase sags to ~50–80 V; the light phase takes ~340–390 V.
4. Low-power electronics fail in fractions of a second.

Georgia grid specifics

• Overhead lines with high phase–neutral loop impedance.
• Main-neutral burns on ageing transformer substations.
• Phase imbalance from Telasi / Energo-Pro feeders.

With a bad N/PE board, the first feeder switch or storm turns the site into a fault zone — even with a sound hybrid from stock.

Why a plain 4P is dangerous — and 3P+N is mandatory

• Standard 4P MCB — forbidden for bypass. Poles are not microsecond-synchronised: neutral can open before the phases. Milliseconds are enough for a ~380 V hit on PSUs.
• 3P+N changeover — safety standard. For service bypass (I‑0‑II) use only Early-make / Late-break devices (IEC 60947-6-1 reference):
  • make: N closes first, before phases;
  • break: N opens last, after phases are dead.

Inversol warranty: who pays

Inversol support rule: burnt varistors, input filters, AC relays and internal boards caused by phase imbalance from open, broken or incorrect neutral switching are not covered under warranty.

Factory analysis separates arc / inter-phase overvoltage from manufacturing defect. Then:

• the owner claims for destroyed loads;
• the supplier refuses warranty repair of the inverter;
• financial liability falls on the installer who wired the board wrong.

That is why Inversol ships hardware from Tbilisi stock and install goes through accredited partners: N/PE is discipline, not a panel detail.

Gold standard: N/PE rules

For Deye, EcoBSS FLEX 3L and related energy storage, four rules apply:

1. Unbroken neutral. N Grid and N Load stay bonded to the site neutral bar. The inverter must not isolate load neutral from earth in island / UPS mode.
2. Certified 3P+N bypass. Manual changeover only with Early-make / Late-break (IEC 60947-6-1).
3. Two-stage residual protection. Grid infeed: selective fire RCD 300 mA; Load branch circuits: group RCD/RCBO 30 mA (Type A).
4. Earthing loop. Site earth electrode within norms (guide ≤ 4 Ω). Inverter chassis and storage frame: separate copper PE ≥ 16 mm².

Schematics, CTs and paralleling — in the INVERSOL FLEX briefing and Academy hub. Field fault lookup: Deye W/F error codes (e.g. F13, F18). Related equipment-class risk: hybrid vs cheap inverter.

Bottom line

Solar commissioning is engineering discipline. Owners: pick firms from the verified partner directory. Installers: full switching and CT base lives in the INVERSOL FLEX technical briefing.

Disclaimer: N/PE rules and RCD ratings are an Inversol engineering guide as of August 2026. Confirm site and DSO requirements on the live project.