Godown Wiring Diagram: How Sequential SPDT Switch Lighting Works
This is a free printable godown wiring diagram: download the diagram as SVG or open it and print to paper or PDF.
A godown wiring diagram shows how a chain of SPDT switches controls warehouse or corridor lights so each switch turns the next light on while turning the previous one off.
Godown wiring is a method of controlling multiple lights in sequence along a corridor, warehouse (godown), or tunnel using a chain of single-pole double-throw (SPDT) switches — also called 2-way switches. The term originates from South and South-East Asian electrical trade practice, where a 'godown' is a large storage building or warehouse.
In a standard godown wiring arrangement, each light fitting is controlled by two adjacent switches: the switch before it and the switch after it. The common terminal of each switch connects to the lamp at that position. The two traveller terminals connect to the common terminals of the preceding and succeeding switches. This creates a sequential chain so that, at any given time, only the light between the switch you just toggled and the next one in the chain is illuminated.
The practical result: when a worker enters one end of a long warehouse, they press the first switch, which lights the first bay. As they walk forward, pressing the next switch turns on the adjacent bay and simultaneously extinguishes the bay they have left. This energy-saving characteristic is the primary reason godown wiring is specified for long corridors, underground passages, and storage facilities where leaving all lights on is wasteful.
Electrically, the circuit uses a single phase line (live) fed through the chain of SPDT switch common terminals, with the neutral returning directly to each lamp. Each switch's two traveller terminals cross-connect to the travellers of its neighbours. The arrangement is distinct from a conventional 2-way (staircase) circuit because it involves three or more switches and lamps in a repeating chain rather than just two switches controlling one light.
Always isolate the supply and verify dead with a calibrated voltage tester before working on any wiring. This diagram is for reference and educational purposes only. Installation must comply with applicable wiring regulations (NEC/NFPA 70, BS 7671, IS 732, IEC 60364) and be carried out by a licensed electrician.
How to wire godown wiring diagram
- Plan the switch and lamp positions Measure the corridor or warehouse and mark the position of each lamp fitting and each switch position. Place a switch at the entry, one between every adjacent pair of lamps, and one at the exit. The number of switches is always one more than the number of lamps.
- Install conduit or cable containment Run conduit or cable trunking between all switch boxes and lamp positions. Godown wiring requires three conductors between each adjacent switch (line, and two travellers), plus separate neutral and earth feeds to each lamp. Plan conduit sizing accordingly.
- Connect the neutral and earth to each lamp Run a continuous neutral conductor from the distribution board to each lamp fitting. Connect the protective earth conductor to the earth terminal of each metal fitting or to the earth pin of each switched live circuit as required by local regulations.
- Wire the switch chain Connect the incoming live (line) conductor to the common terminal of the first switch. Connect that switch's L1 traveller to the common terminal of the second switch; connect L2 of the first switch to the first lamp. Continue along the chain: each switch's common connects to one lamp and to one traveller of its neighbour. Consult a verified circuit diagram before connecting.
- Connect the final switch The last switch in the chain has its common terminal connected to the last lamp. Its traveller terminals connect back to the second-to-last switch's traveller terminals. There is no outgoing line from the final switch beyond the last lamp.
- Test each section before enclosing With a continuity tester (supply isolated and locked off), verify the traveller paths between every adjacent switch pair. Check that no traveller conductor is shorted to neutral or earth. Only after verifying all connections should the supply be restored by a licensed electrician for a live functional test.
- Conduct a live functional test Restore the supply. Toggle each switch in turn and confirm that pressing any switch illuminates the section ahead and extinguishes the section behind. If any lamp fails to respond correctly, isolate, verify dead, and re-check the traveller connections at the faulty switch position.
Specifications
| Supply voltage | 230 V AC (single phase, typical); 120 V AC in North America |
|---|---|
| Supply frequency | 50 Hz (60 Hz in North America) |
| Switch type | SPDT (2-way), minimum 10 A, 250 V AC rated |
| Minimum cable cross-section | 1.5 mm² copper for lighting circuits (BS 7671 / IEC 60364) |
| Circuit protection | 6 A Type B MCB for lighting circuits up to 1 380 W at 230 V |
| Number of control points | 3 or more (minimum 3 switches, 2 lamps); no theoretical upper limit |
| Applicable standards | IEC 60364, BS 7671, IS 732, NEC/NFPA 70, AS/NZS 3000 |
Safety warnings
- Always isolate the circuit at the distribution board and verify the conductors are dead using a calibrated voltage tester (CAT III rated) before touching any wiring. Do not rely on a single test; test line-to-neutral, line-to-earth, and neutral-to-earth.
- Godown wiring must be installed by a licensed or registered electrician in accordance with the applicable wiring regulations: NEC/NFPA 70 (USA), BS 7671 (UK), IS 732 (India), AS/NZS 3000 (Australia/NZ), or IEC 60364 (international). Unauthorised installation may void insurance and create legal liability.
- Do not exceed the current rating of the switches. A 10 A switch must not be loaded beyond 10 A total connected load. Calculate total lamp wattage and ensure the switched current remains within the device rating.
- Ensure all metal parts of luminaires and switch boxes are bonded to the protective earth conductor. A floating earth on a metal fitting is a shock hazard.
- This diagram is provided for educational and reference purposes only. It does not substitute for site-specific engineering design, load calculations, or compliance certification.
Tools needed
- Calibrated voltage tester (CAT III, 1000 V rated)
- Continuity tester or digital multimeter
- Wire strippers and cable cutters
- Screwdrivers (flathead and Pozidriv)
- Cable fish tape or draw wire
- Conduit bender (for metal conduit installations)
- Drill and masonry bits
- Personal protective equipment (insulated gloves, safety glasses)
Common mistakes
- Swapping traveller and neutral conductors at a switch box, which causes a short or incorrect switching behaviour and may energise the earth conductor.
- Using standard single-way switches instead of SPDT (2-way) switches, making sequential control impossible.
- Failing to run a separate neutral to each lamp fitting and instead attempting to complete the neutral through a switch common terminal, which is incorrect and potentially dangerous.
- Incorrectly counting the required number of switches — the chain needs one more switch than there are lamps, not an equal number.
- Connecting the traveller pairs in the wrong order along the chain, which reverses the sequential direction of illumination.
- Not earthing metal switch boxes or conduit fittings, leaving exposed metalwork unearthed.
Troubleshooting
- One lamp does not light regardless of switch position
- Cause: Open circuit in the neutral or switched-live feed to that specific lamp fitting, or a failed lamp Fix: Isolate supply. Check continuity of the neutral and switched-live conductors at the lamp terminals. Replace the lamp if conductors are sound.
- Two adjacent lamps light simultaneously instead of sequentially
- Cause: Traveller conductors between the two adjacent switches have been cross-connected incorrectly, creating a parallel path Fix: Isolate supply. At the switch between the two affected lamps, verify that L1 and L2 are connected to the correct traveller cores going to each neighbouring switch. Re-terminate as per the circuit diagram.
- Circuit breaker trips immediately when supply is restored
- Cause: Short circuit between line and neutral, most likely at a switch box where a traveller was mistakenly landed on the neutral bar Fix: Isolate supply. Disconnect all switch connections and use an insulation resistance tester at 500 V DC to identify the faulted conductor. Re-check every switch termination before restoring supply.
- Switching one switch has no effect on any light
- Cause: Loss of the incoming live conductor at the first switch, or the MCB is off or has tripped Fix: Verify the MCB is in the ON position. Restore supply with supply tester present. Confirm live voltage at the common terminal of the first switch. If no voltage, trace back to the DB and check MCB output.
- Lamps flicker when switches are toggled
- Cause: Loose terminal connection at a switch common or traveller terminal, causing intermittent contact Fix: Isolate supply. Re-terminate all switch connections, ensuring conductors are fully inserted and terminals tightened to the manufacturer's specified torque.
Frequently asked questions
What does 'godown wiring' mean?
Godown wiring is an Indian electrical trade term describing a sequential corridor or warehouse lighting circuit. 'Godown' refers to a large storage building. The circuit uses a chain of SPDT (2-way) switches so that pressing any switch illuminates the next section of the building and extinguishes the previous one, saving energy in long spaces.
How is godown wiring different from staircase (2-way) wiring?
Staircase wiring uses exactly two SPDT switches to control one single lamp. Godown wiring chains three or more SPDT switches with a lamp between each adjacent pair, creating a sequential lighting effect across a long corridor or warehouse rather than toggling a single light from two points.
How many switches are needed for a godown circuit?
The number of switches equals the number of lamps plus one. For example, a five-lamp godown corridor requires six SPDT switches: one at the entry, one between each pair of lamps, and one at the exit. Each switch shares its traveller terminals with its two neighbours in the chain.
What type of switch is used in godown wiring?
Godown wiring uses single-pole double-throw (SPDT) switches, commonly called 2-way switches in the UK, India, and Australia. Each switch has one common (C) terminal and two traveller terminals (L1, L2). The switches are wired identically throughout the chain.
Can LED lamps be used in a godown wiring circuit?
Yes, LED lamps are compatible with godown wiring circuits because the circuit is a simple switched live arrangement with no dimmer or phase-cut control involved. Ensure the LED driver is rated for the supply voltage and that the lamp holder type matches the fitting. Check for any minimum load requirements on the switch.