To wire a "2 way switch 2 lights" setup—controlling two separate lights from two different locations—using electromechanical relays, you should use a 2-pole latching relay (like the ABB E290-24-2) driven by parallel momentary switches. This approach eliminates the need for complex 3-way/2-way traveler wires, allows for unlimited control locations, and handles the high inrush currents of modern LED lighting far better than standard mechanical wall switches.
While traditional mechanical 2-way (UK/AU) or 3-way (US) switches work for simple single-light circuits, scaling up to control two distinct lights simultaneously from multiple locations introduces voltage drop and traveler-wire congestion. Electromechanical latching relays solve this by separating the low-current control circuit from the high-current load circuit.
The Core Decision: Mechanical vs. Electromechanical for 2 Lights
In a standard mechanical 2-way lighting circuit, you run 3-core and earth cable between switches to create "travelers." When you add a second light to the same switched loop, the wiring becomes bulky, and the mechanical contacts inside standard wall switches take a beating from LED inrush currents.
By shifting to an electromechanical latching relay, you change the topology entirely. Your wall switches become simple, parallel-wired momentary push-buttons (or standard single-pole switches used momentarily). These send a brief pulse to the relay's coil. The relay's internal mechanical latch then toggles the heavy-duty contacts, switching both lights on or off simultaneously. This keeps your walls free of high-voltage traveler splices and centralizes the heavy switching in your distribution board or a local junction enclosure.
Electromechanical Relay Rating Table: What Governs Your Load?
Not all relays are created equal. When selecting a component for a 2 way switch 2 lights circuit, you must look at the utilization categories defined by IEC 60947 standards. AC-1 governs resistive and standard lighting loads, while AC-3 governs inductive motor loads. If your circuit includes a ceiling fan alongside the lights, the AC-3 column governs your selection.
| Component / Model | Coil Voltage (A1/A2) | Contact Rating (AC-1) | Breaking Capacity | Best Application |
|---|---|---|---|---|
| ABB E290-24-2 | 24V AC | 16A (230V) | 16A at cos φ=0.6 | Standard residential LED/incandescent lighting |
| Schneider Acti9 TL 16A | 230V AC | 16A (250V) | 16A at cos φ=0.6 | Retrofit boards lacking 24V control transformers |
| Shelly Plus 2PM (Smart Relay) | 24V DC / 110-230V AC | 2x 10A (per channel) | Zero-crossing solid-state | Smart home integration, independent light control |
Wiring the Coil vs. Contact Side (and DC Protection)
An electromechanical relay has two completely isolated circuits: the coil (control) and the contacts (load). Confusing these will instantly destroy the component or create a severe shock hazard.
The Coil Side (A1 and A2)
The coil is an electromagnet. For a 2 way switch 2 lights setup, you wire your momentary wall switches in parallel on the line side of the coil. When any switch is pressed, it completes the circuit to A1, energizing the coil and toggling the mechanical latch. A2 connects to the neutral (for AC coils) or ground/negative (for DC coils).
The Contact Side (1/2 and 3/4)
The contacts carry the mains voltage to your lights. Terminal 1 receives the mains Line (L), and terminal 2 outputs to Light 1. Terminal 3 receives the same mains Line (L) via a jumper from Terminal 1, and terminal 4 outputs to Light 2. The neutrals for the lights are wire-nutted together in the enclosure, bypassing the relay entirely.
Selection Decision Path by Load Type
Choosing the wrong relay for your specific load type is the number one cause of welded contacts and premature failure. Use this decision tree to select the correct electromechanical component.
| If your load is... | And the total draw is... | Then choose this component type... | Specific Part Example |
|---|---|---|---|
| Purely Resistive (Incandescent, Halogen, Heaters) | < 16A | Standard AC-1 Latching Relay | ABB E290-24-2 |
| Capacitive (Modern LED fixtures, CFLs) | < 8A nominal | Oversized AC-1 Relay OR Zero-Crossing Relay | Shelly Plus 2PM (Zero-cross) |
| Inductive (Ceiling fan motor combined with light) | < 10A | AC-3 Rated Contactor (NOT a standard latching relay) | Schneider TeSys LC1D09 |
| Mixed (LED lights + EV charger on same loop) | > 16A | High-capacity DIN Contactor with auxiliary latch | ABB ESB40-40N-06 |
A Note on Breaker Curves
When sizing the Miniature Circuit Breaker (MCB) for this lighting circuit, do not treat fuses and breakers as interchangeable without considering the tripping curve. For a purely resistive or LED lighting circuit, use a Type B MCB (trips at 3-5x In). Type B handles the moderate inrush of lighting without nuisance tripping. Do not use a Type C MCB (trips at 5-10x In) for lighting; Type C is designed for inductive motor loads and will allow dangerous fault currents to persist too long on a standard lighting wire gauge.
Testing Dead and Live: Diagnostics and Repair vs. Replace
When a 2 way switch 2 lights circuit fails, you must determine if the fault lies in the momentary switches, the relay coil, or the relay contacts. Follow this diagnostic sequence.
1. Dead Testing (Power OFF and Locked Out)
Safety First: Turn off the MCB, lock the panel, and verify the circuit is dead with a known-working non-contact voltage tester and a multimeter.
- Test the Switches: Set your multimeter to continuity (Ω). Place probes across the momentary switch terminals. Press the button. You should read < 1 ohm when pressed, and infinite (OL) when released. If it reads open while pressed, the switch is dead.
- Test the Coil: Place probes across A1 and A2. A healthy 24V AC coil will typically read between 50Ω and 200Ω. If it reads OL (open), the internal coil wire is broken.
- Test the Contacts: Place probes across 1 and 2. Manually actuate the relay using the small toggle lever on the front of the housing. You should hear a distinct click and see continuity toggle between OL and < 1 ohm.
2. Live Testing (Power ON - Extreme Caution)
Only perform live testing if dead testing yields inconclusive results and you are qualified to work near live mains.
- Verify Coil Voltage: Set multimeter to AC Voltage. Press a wall switch. Measure across A1 and A2. You must read the nominal coil voltage (e.g., 24V AC or 230V AC). If you read 0V, you have a broken wire in the wall or a failed momentary switch.
- Verify Load Voltage: If the relay clicks but the lights don't turn on, measure between contact terminal 2 and the lighting circuit neutral. If you read 0V, but terminal 1 has 230V, the internal contact is pitted and failed open.
When to Repair vs. Replace
Never repair a sealed electromechanical relay. If the coil is burnt, or if the contacts are pitted/welded, the component must be replaced. Attempting to file down pitted contacts alters the contact pressure and gap distance, leading to severe arcing and potential enclosure fires. A replacement ABB E290 costs roughly $25; the cost of a fire is infinitely higher.
Final Verdict: The Default Pick for 2026
For a standard, non-smart residential 2 way switch 2 lights setup controlling modern LED fixtures, the default recommendation is the ABB E290-24-2 latching relay paired with a 24V AC control transformer and standard momentary wall switches. It provides robust 16A AC-1 contacts, keeps mains voltage out of your wall switch boxes, and easily handles the physical toggling of two simultaneous lighting loads without traveler wire headaches.
If your project requires smart home integration, app control, or independent scheduling of the two lights, bypass the analog relay entirely and install a Shelly Plus 2PM in the ceiling rose or junction box. Its dual 10A channels feature zero-crossing solid-state switching, which completely eliminates contact pitting from LED inrush currents, making it the superior choice for modern capacitive loads.
