1 way vs 2 way light switch
Updated: October 2026
You are in a hallway with a switch at the bottom of the stairs and another on the landing, and the basket says 1 gang 1 way because the plate only has one rocker. That plate will not run the pair. This page on 1 way vs 2 way light switch separates the two words, then shows what COM, L1 and L2 are doing, then points at the only 1-way title in the set. The rows are the mains plates in the [light switch comparison](/hub/electrical-equipment/light-switch). The rule is short. A 2-way plate can do a 1-way job. A 1-way plate cannot do a 2-way job.
You are in a hallway with a switch at the bottom of the stairs and another on the landing, and the basket says 1 gang 1 way because the plate only has one rocker. That plate will not run the pair.
You are in a hallway with a switch at the bottom of the stairs and another on the landing, and the basket says 1 gang 1 way because the plate only has one rocker. That plate will not run the pair. This page on 1 way vs 2 way light switch separates the two words, then shows what COM, L1 and L2 are doing, then points at the only 1-way title in the set. The rows are the mains plates in the light switch comparison. The rule is short. A 2-way plate can do a 1-way job. A 1-way plate cannot do a 2-way job.
Our top picks
| Badge | Product | Ways | Plate | Finish | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  British General BG NBN12 black nickel | 2-way | Metal | Black nickel | 9.4 | about £5.99 | View offer |
 Knightsbridge Knightsbridge CU1000 1-way white | 1-way | Urea | White | 9.2 | about £3.99 | View offer | |
| Best value |  Knightsbridge Knightsbridge CU2000 curved white | 2-way | Plastic | White | 9.2 | about £3.00 | View offer |
On this page
Gang is the rocker, way is the number of positions
A gang is how many rockers sit on the faceplate. Every mains plate in this comparison is 1-gang, so you get one rocker. People read 2-way as two switches on the plate. Gangs are the rockers. Ways are the positions that control the same light. A 2-gang plate is not in these twelve rows. A bedroom with one door is 1-way. A stair with a plate at the bottom and a plate at the top is 2-way. The rocker count can be one in both rooms. The terminal count is what changes. Order the CU1000 because the curved face matches the bedroom, and the stair light then works from downstairs only.
What COM, L1 and L2 are doing
A 2-way switch is a changeover. The usual UK marks are COM, L1 and L2. COM is the common. L1 and L2 are the two throws. On a two-position stair, flipping either rocker changes the state of the lamp. On a 1-way circuit the same 2-way plate still works. Line and switched live go to COM and L1, and L2 stays empty. You do not add a wire to L2 to complete the switch. The Marbo bullets say that white plastic plate can be used as a 1-way or a 2-way. These plates do not require a neutral in the listing. If the photo shows more cores than COM, L1, L2 and an earth, you are no longer in the simple case. The photograph before any core comes out is on how to replace a light switch.
Where the CU1000 fits, and where it does not
The Knightsbridge CU1000 is the only plate in the display titled 1-way. It is 10 A, 230 V, a urea face about 7 mm deep, at £3.99, and 4.6 from 2,984 reviews. The listing’s example is one light in a bedroom or a single-entry room. There is no second throw. CU2000 is the 2-way curved plate at £3.00. The saved listing uses the same image URL for both. If the other end of the hall already has a switch for the same lamp, CU1000 is the wrong basket. The other mains plates are titled 2-way. Marbo says or 1-way in the bullets. A 1-way unit cannot make a 2-way pair.
Three positions is a different switch
Two positions need two 2-way plates. Three or more positions need a 2-way plate at each end and an intermediate in the middle. The intermediate has four terminals. It is not 3-way in the US sense of that phrase. None of the twelve ASINs is one. One position: the CU1000, or any 2-way plate with L2 unused. Two positions: a 2-way plate at each end, which means not the CU1000. Three positions: stop, because the middle device is absent from this set.
Common questions
What is the difference between 1-way and 2-way?
1-way means the light is switched from one position. 2-way means two positions, such as the bottom and top of a stair, either of which can change the light. The usual 2-way plate is a changeover with COM, L1 and L2. A 2-way plate can be wired for one position by leaving L2 empty. A 1-way plate has no spare throw, so it cannot complete a stair pair.
Can I use a 2-way switch on a 1-way circuit?
Yes. Put the line and the switched live on COM and L1, and leave L2 unused. That is the pattern Screwfix and the socket retailers describe, and it is what the Marbo bullets allow by name. You do not need a neutral in the switch box for these listings. You also do not add a dummy wire into L2. If the existing photo shows a more complicated set of cores, stop unless you can name every core.
Can I use the CU1000 at the bottom of the stairs?
No. The CU1000 is titled 1-gang 1-way, at £3.99, 10 A and 230 V. A stair with two plates needs a 2-way mechanism at each end. The CU2000, at £3.00, is the 2-way curved plate that is easy to confuse with it, including a shared image URL in the saved listing. The CU1000 fits a bedroom or other single-entry room where one plate is the only control.
What are COM, L1 and L2?
They are the three terminals on a typical UK 2-way changeover. COM is common. L1 and L2 are the two positions the rocker connects to COM. On a stair, those terminals are how the two plates talk to each other. On a single switch, L2 is the one you leave empty. Marks vary by brand, so the photograph of your old plate outranks a generic sketch.
I have three switches for one light. Which product is that?
An intermediate switch in the middle, with four terminals, and a 2-way switch at each end. None of the twelve listings is an intermediate. A 2-way plate from this set can be one of the ends only if the middle device is already the right part, and buying three 2-way plates will not create that middle. Do not call it a US-style 3-way and then pick the Tap dial because a cell says 4-way. That cell is not a mains intermediate.
Related pages
Sources
Public UK sources are listed below. Shelf prices and star lines are the amazon.co.uk figures checked on 21 October 2026.
- Approved Document P (2013, England) (retrieved 21 October 2026)
- EN 60669-1:2018 in the legislation.gov.uk record of Decision (EU) 2020/1779 (retrieved 21 October 2026)
- BSI: BS EN 60669-1:2018 scope (retrieved 21 October 2026)
- BEAMA: load ratings for manually operated functional switches (retrieved 21 October 2026)
- IET: Section 701, locations containing a bath or shower (retrieved 21 October 2026)
- NICEIC via Voltimum: wall-mounted light switches (retrieved 21 October 2026)
- NICEIC via Voltimum: lighting circuits without a CPC (retrieved 21 October 2026)
- B&Q: how to replace a light switch (retrieved 21 October 2026)