Replacing a Switch in a Switch Board, Step by Step

How to replace a switch in a switch board: the short answer

To replace a switch in a switch board, switch off the MCB feeding that board, prove with a tester that the switch is dead, remove the cover plate and the old switch, move each wire to the same terminal on a new switch of the same rating and type, refit it, restore power and test.

1. Switch off the MCB and test with a tester that every terminal of the switch is dead.
2. Buy a matching switch: same rating, same 1 way or 2 way type, same module size and range.
3. Photograph the wiring, then remove the cover plate and ease the old switch forward.
4. Move the wires one at a time to the matching terminals and tighten each one firmly.
5. Refit, switch the MCB back on and test the switch, then check the plate stays cool.

The steps are simple. What makes the job safe or dangerous is the first one, and everything below assumes you do it every time. On a modular board the switch is a module that unclips from a frame; on a conventional board it is screwed to the sheet.

We manufacture switches, sockets and plates in Mumbai, so we can tell you what to match on the product. We cannot see your wiring. If anything behind the plate looks wrong, or you are unsure at any point, stop and call a licensed electrician.

Before you start: when to call an electrician instead

Call a licensed electrician instead of changing the switch yourself if you see burn or melt marks, brittle or cracked insulation, aluminium wires, a switch that is hot to the touch, or if you cannot tell which MCB feeds the board, because each of these means the circuit, not just the switch, needs attention.

The warning signs: burn or melt marks on the switch or plate, brittle or cracked insulation, aluminium wires, a switch that is hot to touch. Also leave these to an electrician: a DP switch for a geyser or AC, which breaks two conductors; a 2 way switch whose wiring you cannot identify; and any change of rating, which may mean the circuit itself needs changing.

What you need before you start

You need four things before you replace a switch: access to the MCB board so you can switch off the circuit, a line tester to prove the switch is dead, an insulated screwdriver that fits the terminal screws, and a replacement switch that matches the old one in rating, type, module size and range.

The line tester is the one tool that must not be skipped. We make two in our VIYONA range: the 811 at ₹36 and the 812 at ₹42, on the VIYONA line tester page. Add an insulated screwdriver, a phone camera for the before photo, and a torch, because the lights on that circuit will be off.

The table above sums up each step, what you need for it and what to check.

Step 1: switch off the MCB and prove it dead

Find the MCB for the circuit in the distribution board and switch it off. If the MCBs are not labelled, switch off the main. Tell everyone at home that you are working on the circuit so nobody switches it back on.

Then, at the switch board, check with a tester that the terminals of the switch you are replacing are dead. Check the tester first on a socket you know is working, then on the switch terminals, then on the working socket again, so a faulty tester cannot fool you. Test every terminal on the board, not only the one switch: one board can be fed from two circuits, for example lights from one MCB and sockets from another.

Our guide on which MCB for home explains what each MCB in the board protects, which helps when the labels have worn off. A board with labelled MCBs turns this step into a minute’s work.

Step 2: buy the right replacement switch

Take the old switch, or a clear photo of its back, to the dealer. Match four things: the rating printed on the switch; the type, whether 1 way, 2 way, bell push or with indicator; the module size, 1M or 2M; and the range, because a module clips most securely into a frame of its own range.

Some worked examples at our printed MRPs. A KEMPS Peony 10AX 1 way light switch is the K101 at ₹65 in white; its 2 way twin is the K102 at ₹105. A 20AX 1 way for a heavier point is the K106 at ₹107. On a conventional board, the VIYONA 151 1 way switch with ISI mark is ₹74.

Step 3: remove the plate and the old switch

On a modular board, unscrew or unclip the cover plate. The switch modules are clipped into a frame behind it; press the clips at the side of the module to release it from the frame and ease it forward on its wires.

On a conventional board, unscrew the sheet or the switch fixing screws and pull the switch forward. Either way, do not pull the wires hard: old insulation can crack, and a wire that snaps inside the box is no longer a switch swap.

If the plate itself is cracked or yellowed, replace it at the same time. Our modular plates are UV-protected, do not turn yellow, fit all major modular switch systems and carry a 5-year warranty; modular plate sizes explained shows how to read the M size.

Step 4: move the wires one at a time

Loosen one terminal on the old switch, take out its wire, and fit it into the matching terminal on the new switch before touching the next wire. Tighten the terminal screw firmly on the bare copper, with no insulation under the screw and no stray strands.

A 1 way switch has two wires and it usually does not matter which goes where. A 2 way switch has three, and the common wire must go to the common terminal. If the old switch’s markings do not match the new one’s, stop and call an electrician.

Step 5: refit, restore power and test

Fold the wires neatly back into the box without pinching them behind the frame, clip the new module into the frame (or screw the switch to the sheet), and refit the cover plate. Then switch the MCB on and test the switch several times.

Afterwards, touch the plate after the load has run for a while. It should stay cool. A switch that feels warm on a normal load has a loose connection or the wrong rating. If the MCB trips the moment you switch it on, something is shorted: leave it off.

Switch board connection: what each wire does

In a typical switch board connection, the phase wire from the MCB comes into the board and is looped to one terminal of every switch, each switch sends a switched live wire out to its light or fan, the neutral goes straight to the loads and sockets, and the earth wire goes to the earth pin of each socket.

That is why a switch always sits in the phase, never the neutral: switched on the neutral, a light holder would stay live even when off. Sockets on the board also need the earth. In many Indian homes, older wiring uses red for phase and black for neutral, while newer cable may be brown and blue; earth is green or green and yellow.

What each of the three conductors does, and why the neutral is not safe to touch, is explained in our guide to phase, neutral and earth.

For the whole board drawn out wire by wire, with a fan regulator, an indicator and a 3 pin socket, see our switch board wiring diagram. Replacing a 2 way switch means finding the COM wire first; our 2 way switch wiring diagram shows which of the three wires that is.

How to replace a geyser switch

To replace a geyser switch, switch off the geyser’s MCB, prove the switch dead with a tester, and fit a double pole switch of the same or higher rating, usually 32A, moving the phase and neutral wires to their matching terminals; because the load is heavy and the room is wet, we recommend an electrician does it.

A geyser switch is usually a 20A or 32A DP (double pole) switch, with an indicator so you can see from outside the bathroom that it is on. Replace it only with a switch of the same or higher rating and the same number of poles.

Product pages: the KEMPS K516 32AX DP switch with indicator, the VIZA Cherry V1250 32A DP switch and the VIYONA 32A DP switch. A geyser circuit should be checked for proper protection at the same time; our MCB guide covers the geyser circuit.

Changing a socket or regulator on the same board

The same five steps apply to a socket or a fan regulator on the board, with one extra check each. For a socket, match the rating: a 6A socket for phone chargers and lamps, a 16A socket for heavy appliances. The KEMPS K193 6A and 16AX universal socket with shutter takes both plug sizes at ₹205. Our 6A vs 16A socket guide goes appliance by appliance.

A socket carries three wires, phase, neutral and earth, and the earth must go back on the earth terminal. For a fan regulator, match the steps and the module size: the KEMPS K213 Tiny is a 4-step regulator at ₹405 and the K214 Duro a 5-step at ₹450. Our guide to fan regulator types explains the options.

Upgrading while you are there

If the whole board is old, yellowed or a conventional sheet, this is a good moment to consider a modular board: each switch can then be replaced on its own in future, as a single clip-in module. That usually needs a new box sized for the modular plate, which is an electrician’s job, not a switch swap.

Our comparison of modular vs normal switches covers the trade-offs, and our guide to upgrading a whole house to modular switches covers boxes, room order and cost. The plate size calculator tells you which plate fits the switches you need.

We have made these parts in Mumbai since 1995, under ISO 9001:2015.