3-Source Changeover Wiring Pakistan 2026 — Grid + Solar + Generator
How do I wire a 3-source changeover (grid + solar + generator) in Pakistan?
A Pakistani 3-source changeover panel uses either a 5-position cam-type EP changeover switch (0-1-2-3-4) for manual operation, OR a programmable 3-position automatic transfer switch (ATS) with priority logic (grid → solar → generator → off). Critical wiring rules: the NEUTRAL is switched along with phase to prevent backfeed; only one source is connected at any time (interlock-prevented); solar and generator must NEVER feed grid simultaneously (NEPRA net-metering compliance + utility-worker safety). Built to IEC 60947-3 + IEC 60947-6-1 for transfer-switching equipment.
The 3 Pakistani wiring topologies
Topology A — Manual 5-position EP changeover (cheapest)
Single rotary cam switch (4-pole, 5-position: OFF / Grid / Solar / Generator / Solar+Grid). Manual operation by the householder during outages. Cost: PKR 3,600 for the changeover + PKR 1,000 wiring + PKR 2,000 enclosure = ~PKR 6,600. Pros: cheap, foolproof, no electronics to fail. Cons: requires manual intervention; risk of forgetting and running on multiple sources accidentally.
Topology B — 2 manual + 1 automatic (most common Pakistani solar prosumer)
Solar hybrid inverter has built-in grid-tie + battery backup. Generator gets a separate YCQ1B 4P 63A ATS (PKR 8,200) downstream of the solar inverter output. Pros: solar auto-fails over to grid; generator only kicks in on full outage. Cons: requires hybrid inverter with proper grid-export priority logic.
Topology C — Full 3-source ATS (commercial / industrial)
YCQ6 4P motorised ATS (PKR 18,500–89,000 by amp band) with programmable priority. PLC reads voltage on each source, switches to highest-priority available. Pros: full automation, sub-second transfer. Cons: cost, complexity.
The critical wiring rules (NEPRA-compliant)
- Switch NEUTRAL with PHASE (always 4-pole on 3-phase, always 2-pole on single-phase). A 3-pole-only switch leaves shared neutral creating ground loops + safety risk.
- Mechanical interlock — never possible to have grid + solar inverter + generator all connected simultaneously. Single-throw position OR programmed mutex.
- Grid disconnect during generator operation — per NEPRA Distribution Code Section 7, generator must NEVER back-feed grid. Solar net-metering exempt only when bi-directional meter is fitted and prosumer agreement is signed.
- Earth bonding maintained — common earth bus for all three sources; switch transfers phase + neutral but earth stays continuous.
- SPD across all 3 sources — install Type 2 AC SPD (YCS6-B 385V) at the upstream side of each input. Lightning enters via any of the three.
Sizing table — by Pakistani property size
| Property | Phase | Recommended changeover | PKR |
|---|---|---|---|
| 2-bed apartment / 5-marla | 1φ | YCBZ-63 2P 63A 3-pos (grid/solar/gen) | 1,500 |
| 10-marla 3-phase house | 3φ | EP 4P 63A 5-position | 3,600 |
| Commercial 100-200A | 3φ | YCQ6 4P 200A motorised ATS | 38,000 |
| Factory 400-630A | 3φ | YCQ6 4P 630A motorised ATS | 89,000 |
Common Pakistani installer mistakes
- Switching only the phase, not the neutral — creates ground loop between grid and gen earth grids; ELI tripping random RCBOs.
- No interlock between solar and generator — solar inverter back-feeds the running generator → inverter damage + generator AVR damage.
- Same MCB on all 3 sources — nuisance trips when one source has high inrush at transfer.
- Skipping SPD on generator side — generator output is "clean" but voltage transients during start/stop pulses still damage downstream.
- Wrong amp rating on the changeover — sized to the smallest source instead of the largest. ATS must handle the highest-current source's full FLA.
Buy + related
All changeovers (YCBZ family) · ATS (YCQ family motorised) · Cam-type EP changeover · K-Electric tariff hike playbook