Modular Plate Sizes Explained: 1M to 18M

What a module is, and what “1M” to “18M” means

A module is the standard width unit of a modular wiring device. A single switch occupies one module; a socket or a fan regulator occupies two. The number in a plate size is simply how many of those units the plate will hold: a 4M plate has room for four modules, a 12M plate for twelve.

That makes the plate size a count, not a measurement. Two plates labelled 6M from two different designs can differ by a few millimetres on the outside, but both carry six modules of the same system behind the opening. The size you need is therefore decided by what goes behind the plate, not by how big the wall looks.

Plates, grid frames and back boxes all use the same numbering, which is why a plate is always ordered together with a box of the same size. Get the module count right first and the rest of the order follows from it.

The sizes we make: 1M to 18M

Across our KEMPS and VIZA modular ranges, plates come in a core set of nine sizes. Every one of them appears in our current KEMPS and VIZA price lists and in the catalogue.

1M 2M 3M 4M 6M 8M horizontal 8M square 12M 18M

There is no 5M, 7M or 9M plate If your count lands between sizes, go up to the next one and fill the gap with a blank module. That is the normal way to do it, not a workaround.

A few designs add sizes outside the core set, covered further down: 16M in Cherry, Aqua Cherry and Teyoma, and 10M plus square and horizontal 12M in V-Wood. The full list by design is on our modular plate manufacturer page and in the catalogue.

What fits in one module, and what takes two

To count modules you need the width of each device. These are the widths printed in our own KEMPS and VIZA lists:

1M 6A, 10A and 20A one-way switches in the Peony, Daisy, Orchid, Piano, Mirchi, Royal and Slim families; the TV socket; the telephone jack; the one-line RJ45 jack; the single blank plate.

2M 6A and 16A sockets; fan regulators and dimmers; the 32A DP switch; 20A switches in the 2M Aster, Royal and Air families; the RJ45 computer jack; the buzzer; the LED night lamp and dome light.

4M The foot light, which is easy to forget until the plate is too small for it.

Some switches come in both widths The Peony, Daisy and Orchid families each list a 20A switch at 1M and another at 2M. Pick the exact product before you finish counting.

How many modules do I need? Count, then round up

The method is the same for every location on every wall. Walk the room, decide what that one board has to control, and add the widths.

Step 1 List every switch, socket, regulator and jack for that spot.

Step 2 Add their widths using the list above: switches 1M, sockets and regulators 2M.

Step 3 Round up to the next plate size we make, and fill any gap with a blank.

A worked example: a bedroom entry board with three light switches (3M), one fan switch (1M), a fan regulator (2M) and one socket (2M) adds up to 8M. That is exactly an 8M plate, horizontal or square, depending on the wall.

Leave one spare module A room usually gains a device after the walls are painted: a second light, a charger point, a smart module. A spare slot behind a blank costs very little now; a larger box later means cutting the wall.

Typical plate sizes by location

Once you know the widths, most boards in a home land on a few familiar sizes. These are worked from the device widths above, not rules; your own count always wins.

1M–2M A single bell push, a lone switch in a store room, or a TV or data point on its own.

3M–4M A bedside: a switch or two plus one socket. A 4M plate holds two switches and one 2M socket.

6M A kitchen counter or study table: two sockets and two switches.

8M A bedroom or living-room entry board with lights, fan and regulator.

12M–18M A living-room main board or a hall that controls many circuits from one place.

Horizontal or square: how the bigger plates are laid out

Up to 8M, a plate can be a single row of modules that simply gets wider. Beyond that the modules are stacked in rows, and the plate grows in height instead — and 8M itself comes both ways.

8M horizontal One long row, 260 mm wide in our Aster and Royal plates. Suits a wide wall beside a door frame.

8M square Two rows of four, 160 mm by 150 mm. Suits a narrow wall between a door and a corner.

Order the box to match the layout An 8M horizontal and an 8M square hold the same modules but need different back boxes. Our catalogue lists them separately for exactly that reason.

Why 1M and 2M plates are the same size on the wall

Something that surprises people when they open our catalogue: in the Aster and Royal plates, the 1M and 2M plates are both printed at 100 mm by 95 mm. The outer face is the same; only the opening behind it changes.

100 × 95 mm Both the 1M and the 2M plate, as printed for Aster and Royal.

1M/2M Our concealed and surface unbreakable boxes list a single 1/2M size that serves both plates.

Practical upshot Choosing 2M over 1M costs no extra wall space. If a single switch might one day become a switch and a USB point, a 2M plate with a blank leaves room for it.

The back box decides the plate size

A plate screws onto a box buried in the wall, and the box is sized in the same modules. The two must match. Our catalogue lists concealed boxes in unbreakable plastic and in G.I. sheet metal, and surface boxes for walls that cannot be chased.

Concealed G.I. box 1M, 2M, 3M, 4M, 6M, 8M horizontal, 8M square, 12M, 16M and 18M.

Concealed unbreakable box 1/2M, 3M, 4M, 6M, 8M horizontal, 8M square, 12M and 18M.

Surface gang box From one-way to eighteen-way, matched to the VIZA plate range.

More on the boxes themselves is on our gang box page.

Sizes only some designs offer: 16M, 10M, 6M vertical

Beyond the core nine, a handful of designs carry extra sizes. If a drawing calls for one of these, choose the design first.

16M Listed in the VIZA Cherry, Aqua Cherry and Teyoma plates, 260 mm by 190 mm in Teyoma.

10M 12M square 12M horizontal Listed in the VIZA V-Wood plates, which also run taller than most at 116 mm.

6M vertical Listed alongside the standard 6M in one of the VIZA Royal catalogue listings, for a narrow strip of wall.

Module widths vary across brands; our plates are built to fit

The module is a unit within a system, not a national dimension. Across the market, one manufacturer’s module is not guaranteed to sit correctly in another manufacturer’s grid frame or plate, even when both say 1M.

Our plates: compatible with all major modular systems We design our plates to take the modules of all major modular switch systems, and they carry a 5-year warranty. Upgrading the finish does not mean replacing every switch behind it.

Mixing other brands’ plates and devices Check the fit first. Devices may clip in loosely or not at all when neither side is built for cross-compatibility.

Reusing an old box for a new brand Box fixing centres and depths vary; the plate may never sit flush.

One count per board Whatever brands you use, count widths from the catalogue of the devices you will actually fit.

We cover what else separates ranges in how to choose a modular switch brand.

Where the plate size fits in the whole board

The plate is one of three parts of a switch board, alongside the grid frame the devices clip into and the box in the wall. Size, then rating, then finish is the order that avoids rework.

Size Fixed by the module count and the box. Decided first, at the wiring stage.

Rating Which switch and socket each appliance needs. Our switch board guide covers 6A against 16A.

Finish Chosen last, from 13 plate designs across KEMPS and VIZA, in gloss, metallic, textured and wood effects. Our guide to modular plate finishes compared helps you pick one.

Choosing the finish first The usual way a board ends up one size too small.

Ordering plates: what to hand your dealer

We sell through dealers and distributors, so the order usually starts as a list at the counter. A clear list saves a second trip.

Per location Plate size, and whether 8M is horizontal or square.

Per plate Design, finish and series: KEMPS or VIZA.

Per box Matching size and type: concealed G.I., concealed unbreakable or surface.

Blanks One 1M blank for each spare slot you planned in.