1 Way or 2 Way Switch? How Each Works and Where It Goes

1 way vs 2 way switch: the short answer

A 1 way switch has two terminals and turns a light on or off from one place, while a 2 way switch has three terminals and, fitted as a pair joined by two wires, lets you turn the same light on or off from two places, such as the top and the bottom of a staircase.

A 1 way switch has one job: it connects or breaks the live wire to a light or appliance. Almost every switch in a home is a 1 way switch. A 2 way switch has a common terminal and two others, often marked L1 and L2, and its lever connects the common terminal to one or the other. That changeover is what lets two switches share one light.

We make both types in 10AX and 20AX ratings across our KEMPS and VIZA modular ranges, and in our VIYONA conventional range. The difference in price is small; the difference in wiring is what matters, because a 2 way pair needs extra wires run between the two switch positions. For bell pushes, indicator switches and DP switches, see our guide to the types of electrical switches and their uses.

How to tell a 1 way switch from a 2 way switch

The quickest way to tell a 1 way switch from a 2 way switch is to count the terminals at the back: a 1 way switch has two, a 2 way switch has three, and the extra one is the common terminal that the lever swings between the other two. From the front, the two usually look identical.

Look for three things. The 2 terminals of a 1 way switch, or the 3 terminals of a 2 way. The markings next to them, commonly C or COM for the common and L1 and L2 for the other two. And the code on the box: in our KEMPS Peony range the K101 is the 10AX 1 way and the K102 the 10AX 2 way; in VIZA the V1215 and V1216; in VIYONA the 151 and 152.

The table below puts the differences side by side.

How a 2 way switch works

Picture two switches, A and B, one at each end of a staircase. The live wire goes to the common terminal of switch A. Two wires, often called travellers, run from A’s L1 and L2 to B’s L1 and L2. The common terminal of switch B goes to the light.

The light is on when both switches point to the same traveller, and off when they point to different ones. Flip either switch and the state changes. That is the whole trick, and it is why a 2 way circuit needs extra wires between the two switch positions.

One way and two way switch diagram

A one way switch diagram is a single loop: the phase goes into the switch, out to the light, and back on the neutral, while a two way switch diagram adds two traveller wires between the switches, with the phase on the common terminal of the first switch and the light on the common terminal of the second.

We draw both below as the path the current takes. In each, the switch sits in the phase wire and the neutral goes straight to the light. Switching the phase, not the neutral, is standard practice: a light switched on the neutral stays live at the holder even when it is off.

A 1 way switch is one of several modules on a board; our switch board wiring diagram shows how the phase loops from switch to switch. For the full staircase circuit drawn wire by wire, including two lights on one pair, see our 2 way switch wiring diagram.

Where to use a 1 way and a 2 way switch

Use a 1 way switch wherever a light or appliance is controlled from a single place: most room lights, fans, a geyser, a socket. Use 2 way switches wherever you would otherwise walk in the dark to reach the switch: a staircase, a long corridor, a bedroom with the light switched at both the door and the bed.

For the bedside, a modular 2 way switch in a board next to the bed is the tidy option. On a conventional installation, our VIYONA range also makes a 2 way bed switch (code 186, ₹40), listed with the other VIYONA bed and surface switches.

For how many modules each board needs once the 2 way switches are counted in, see how to choose a switch board.

ITI students meet both switches together in the godown wiring practical, where one 1 way switch and a chain of 2 way switches light a row of lamps one at a time; see our godown wiring diagram.

Can a 2 way switch be used as a 1 way switch?

Yes, a 2 way switch can be used as a 1 way switch: connect the incoming wire to the common terminal and the outgoing wire to either L1 or L2, and leave the third terminal empty, and it switches a light from one place exactly as a 1 way switch would, only at a slightly higher price.

It works. Some electricians stock only 2 way switches for this reason, so one box covers every point. The trade-off is cost. A 2 way switch costs more than a 1 way of the same range: in our KEMPS Peony range the K101 10AX 1 way is ₹65 in white and the K102 10AX 2 way is ₹105. In KEMPS Orchid the K141 is ₹65 and the K142 ₹115. Across a whole house, fitting 2 way everywhere adds up.

The reverse does not work: a 1 way switch has no changeover, so it cannot be one half of a staircase pair.

What does 1 gang or 2 gang, 1 way or 2 way mean?

Gang is the number of switches in one unit and way is how many places each switch works with, so a 1 gang 1 way switch is a single lever that controls a light from one place, while a 1 gang 2 way switch is a single lever that works with a partner switch elsewhere, as on a staircase.

The same counts apply to bigger units: a 2 gang 1 way switch has two separate levers that each control their own light from one place, and a 2 gang 2 way switch has two levers that are each one half of a staircase-style pair.

A 2 gang 1 way 2 way switch mixes them: one ordinary lever and one 2 way lever in the same unit. Our KEMPS Aster range makes this concrete, with two switches in one 2M module: the K171 carries two 10AX 1 way switches, the K172 two 10AX 2 way switches, and the K173 one 1 way plus one 2 way.

VIZA has the same idea in its Air line: the V1291 with two 10AX 1 way switches at ₹165, the V1292 with two 10AX 2 way at ₹300 and the V1293 1 way plus 2 way at ₹250.

10A or 20A: which rating for a 2 way switch?

A 2 way switch is rated exactly like a 1 way switch, by the load it controls: a 6A or 10AX switch is correct for lights and fans, which is what almost every staircase and corridor pair switches, and a 20AX switch is for a heavier load that needs control from two places.

In our KEMPS Peony range, the 10AX 2 way is the K102 (₹105) and the 20AX 2 way the K107 (₹132), both 1M. The K112 is a 20AX 2 way in a 2M size at ₹195. In VIZA the V1212 is a 20A 2 way at ₹127. The X in 10AX and 20AX marks a switch rated for the inductive loads of fans and lamp drivers.

Our switch and socket ratings table lists every rating we make, and our guide to switch types and ratings explains 6A, 10AX, 16A, 20AX and 32A.

Can you control a light from three places?

Yes, a light can be controlled from three or more places by fitting an intermediate switch between the two 2 way switches; it has four terminals and crosses the two traveller wires over, so flipping any one of the three switches changes the state of the light, whatever the other two are doing.

Each extra position needs one more intermediate switch with 4 terminals, and the travellers have to run through every switch position in turn. That is more wire and more planning than a simple pair.

For most homes a 2 way pair covers every staircase and corridor. Three positions tend to come up in a long hall with three doors or a duplex landing.

1 way vs 2 way switch price

In our ranges a 2 way switch adds between 16 and 50 rupees over the 1 way of the same range and rating. The gap is smallest in VIYONA conventional switches and widest in KEMPS Orchid. From our current catalogue:

Product pages with photos: KEMPS K102 10AX 2 way, KEMPS K142 10AX 2 way and KEMPS K107 20AX 2 way. The VIYONA pair is on the VIYONA 16A switch and universal socket page, and the VIZA codes on VIZA switches and sockets.

MRP is the printed maximum retail price. We sell through dealers, by phone and at our Mumbai works, not online.

Planning 2 way switches before the walls are closed

The cheapest time to add a 2 way switch is before plastering. The two traveller wires between the switch positions run through conduit in the wall; adding them after the walls are finished means chasing new channels or running surface conduit. Walk through the house with the electrician and decide every place you would want to switch a light from.

Three places are commonly forgotten: the bedroom light at the bed, the passage light at both ends, and the terrace or balcony light at both the door and the far end. Each needs a 2 way switch at both positions, so count them in pairs when you order.

On a modular board, a 10AX 2 way switch such as the K102 takes the same 1M space as a 1 way, so it changes nothing about the plate size. Our plate size calculator works out the plate for the mix of switches on each board, and modular plate sizes explained shows what each size holds.

Why does a 2 way switch work from only one end?

When a staircase light works from only one of its two switches, the usual cause is that the common wire has been connected to an L1 or L2 terminal at one of the switches, or that one traveller wire is loose or broken, so certain lever positions leave no complete path to the light.

Other signs point the same way: the light works only when one switch is in a particular position, or it flickers when a lever is touched, which suggests a loose terminal. A switch plate that feels warm is a separate warning; read what a hot switch or sparking socket means.

If the fault turns out to be a worn switch, the fix is a like-for-like replacement: same 2 way type, same rating, same range.