Testing Shower Selector Switches: Cold, Eco & High Power Diagnostics

⚠️ SAFETY FIRST: READ BEFORE STARTING

Working on electric showers is dangerous. You are dealing with a high-voltage appliance (240V) and water.

• ISOLATE POWER: Always turn off the electricity at the main consumer unit (fuse box) and pull the isolation cord before removing the shower cover.

• VERIFY DEAD: Use a voltage tester to ensure no power is reaching the unit.

• LEGALS: In the UK, major electrical work in bathrooms is "Part P" regulated. If you are not a competent person or are unsure of these tests, stop and consult a Part P qualified electrician.

• DISCLAIMER: You follow these guides at your own risk. This site and its authors are not liable for any injury, loss, or damage caused by your repairs.

How the Selector Switch Works (The Power Map)

Setting	Microswitches Engaged	Heater Elements Active
Cold	None	0 (Water only)
Eco (Low)	Switch 1 Only	1 Element (Approx. 4kW)
High	Switch 1 & Switch 2	2 Elements (Full Power 8.5kW+)

See this entire process in the video below 

The Diagnostic Test:

1. Isolate Power (Mandatory!).

2. Set multimeter to Continuity (Beep).

3. Place probes on the terminals of the microswitch.

4. Manually click the switch lever.

• Beep on click: Switch is good.

• No Beep: Internal contacts are burnt. Replace the switch.

When testing switches, don't just look for continuity. Look at the plastic casing around the spade connectors. If the plastic is discoloured (brown/black), the switch has been overheating due to a loose connection. Even if it 'beeps' now, it will fail under the high load of a 40-Amp shower. Replace it immediately to prevent a fire hazard.

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Need a Multimeter for testing try on Ebay UK here