Replace a 45A shower pull cord isolator switch

Helpful video reference. Matt (On Site with Matt) demonstrates the wiring tips for an electric shower pull cord switch in his video "Tips For Wiring up an Electric Shower Pull Cord". He covers terminal layout, making good connections and a practical tip on the cord itself. Worth watching before you open the ceiling rose.

1. Check what you have and buy the right replacement

Before ordering anything, look at the existing switch. The amperage rating is printed on the switch body -- usually on the front or on a label visible when the cover is removed. For a shower circuit it will be 45A.

Also check the mounting. Most shower pull cord switches are ceiling-mounted on a round or rectangular surface pattress. A few older properties use wall-mounted pull cord switches outside the bathroom zone. Buy a replacement that matches the same mounting style.

A switch with a neon indicator costs a little more but is worth it. The neon tells you at a glance whether the circuit is live, which is useful if someone turns the MCB off at the board without telling you the shower is broken.

2. Isolate at the consumer unit

Go to the consumer unit and switch off the shower circuit. It is usually clearly labelled "shower" and protected by a 40A or 45A RCBO or MCB -- often the widest device in the board.

If the board is not labelled, see the guide on labelling your consumer unit. For now, you can identify the shower circuit by turning off each device in turn until the shower loses power.

Once off, use an approved voltage tester at the pull cord switch to confirm the circuit is dead. Touch the tester to the live terminal and the neutral terminal. Both should read zero. Only proceed when you are confident the circuit is dead.

3. Remove the old switch

Unscrew the pull switch from the ceiling pattress. There are usually two screws on the front face. Ease the switch body down on its cables -- you do not need to disconnect anything yet.

Take a clear, well-lit photograph of the terminal block before disconnecting anything. This is your insurance if you get confused mid-job or if a conductor spring out. Label the photo if it helps.

Standard shower pull cord switch connections are: Line supply (L1 or COM), Line load (L2 or LOAD), Neutral supply, Neutral load, and Earth. Some switches label them slightly differently, but the principle is the same: two poles, each with a supply side and a load side.

4. Transfer the wires

Loosen each terminal on the old switch one at a time, and move the conductor directly to the corresponding terminal on the new switch. Work one conductor at a time -- do not disconnect everything at once.

The cable into the switch is typically 6mm² twin and earth. Check the insulation is undamaged before inserting each conductor. The earth conductor should have green-and-yellow sleeving. If it is bare, sleeve it with a short piece of green-and-yellow before fitting.

Tighten each terminal screw firmly. Shower circuit conductors are large enough that a loose terminal can arc and overheat under the high current. Give each conductor a gentle pull to confirm it is held.

5. Refit and test

Fold the cables carefully back into the ceiling pattress. Do not trap any insulation under the switch body. Screw the switch up firmly so it sits flush against the ceiling -- a poorly supported switch will vibrate under load.

Go back to the consumer unit and switch the shower circuit back on. Return to the bathroom and check the pull cord operates the switch smoothly. The neon indicator (if fitted) should light when the switch is in the ON position.

Run the shower for at least two minutes at maximum power setting. Feel the pull cord switch briefly -- it should be no more than slightly warm. If it feels hot, switch off immediately and check the terminal connections.

When to call us

A straightforward pull cord switch swap is within reach for a careful homeowner. The moment the cable looks wrong, the terminals show signs of arcing, or the switch runs hot, that is a call for an electrician. Shower circuits carry high currents and the consequences of a bad connection can be serious.

For small jobs in Sandwich and east Kent, Richard charges at the £10 per 10-minute rate. A shower switch change takes around 20 to 30 minutes on site.