Why Does My RCD Keep Tripping? Common Causes and Fixes

What Is an RCD and Why Does It Trip?

An RCD (Residual Current Device) is a life-saving device in your consumer unit that instantly cuts power when it detects electricity leaking to earth. This protects you from electric shock and reduces fire risk.

When RCD Tripping Is Normal

RCDs are designed to trip. A single trip that resets easily usually means:

• It detected a genuine fault and protected you
• A temporary issue like moisture has cleared
• An appliance had a momentary fault

When RCD Tripping Is a Problem

Repeated tripping indicates an underlying issue that needs investigating.

Common Causes of RCD Tripping

1. Faulty Appliances

The most common cause. An appliance with damaged insulation or internal fault leaks current to earth.

How to Find the Faulty Appliance:

• Switch off and unplug everything
• Reset the RCD
• Plug in appliances one at a time
• The one that trips the RCD is faulty

2. Water or Moisture Ingress

Water conducts electricity and causes earth leakage:

• Outdoor sockets - Damaged weatherproof covers
• Bathroom fans - Condensation in connections
• Kitchen appliances - Water in connections
• Garden lighting - Failed seals

Signs of Moisture Issues:

• Trips more often in rain or humidity
• Trips after using shower or bath
• Trips when using outdoor equipment

3. Old or Deteriorating Wiring

Older properties may have insulation breakdown:

• Rubber-insulated cables - Crumble with age
• Damaged cables - Rodents, DIY damage
• Overheated connections - Cause insulation failure

Warning Signs:

• Random tripping with no pattern
• Trips getting more frequent over time
• No obvious faulty appliance

4. Nuisance Tripping

Sometimes RCDs trip without a genuine fault:

• Too many appliances - Cumulative small leakages
• LED lighting - Some LEDs cause interference
• Long cable runs - Natural capacitance to earth
• Sensitive RCD - May need upgrading

5. Faulty RCD

RCDs themselves can fail:

• Mechanical wear - Contacts deteriorate
• Age - Recommended replacement every 10-20 years
• Manufacturing defect - Rare but possible

Troubleshooting Steps

Step 1: Identify Which RCD

Most consumer units have multiple RCDs. Note which one is tripping.

Step 2: Unplug Everything

Unplug all appliances from the affected circuits.

Step 3: Reset the RCD

Push the switch firmly upward. If it holds, proceed to Step 4.

If it won't reset:

• There's a wiring fault (not an appliance)
• Call an electrician

Step 4: Reconnect One by One

Plug in each appliance individually, waiting 30 seconds between each.

If a specific appliance trips it:

• That appliance is faulty
• Don't use it - get it repaired or replaced

Step 5: Check for Patterns

Note when tripping occurs:

• Time of day
• Weather conditions
• Which appliances in use
• Which rooms affected

When to DIY vs Call an Electrician

Safe to Handle Yourself

• Unplugging faulty appliances
• Resetting tripped RCD
• Testing appliances to find fault
• Replacing obviously damaged plugs

Call an Electrician

• RCD won't reset at all
• No faulty appliance found
• Tripping continues after removing appliances
• Burning smell or scorch marks
• Old wiring suspected
• Tripping started after building work

Common Fixes We Perform

RCD Types and Sensitivity

Understanding Your RCD

30mA RCDs are most common in homes and provide shock protection.

Modern Consumer Units

Current regulations require:

• RCD protection on all circuits
• Maximum 30mA for socket outlets
• Split protection (two RCDs minimum)

Preventing Future Trips

Regular Maintenance

• Test RCDs monthly - Use the test button
• Inspect outdoor sockets - Check seals and covers
• PAT test appliances - Especially older ones
• Watch for warning signs - Flickering, burning smells

Upgrade Considerations

If you have frequent nuisance tripping:

• RCBO consumer unit - Individual circuit protection
• Time-delayed RCDs - For circuits with motors
• Dedicated circuits - For problematic appliances

Frequently Asked Questions

Why does my RCD trip at night?

Common causes: fridge/freezer cycling, immersion heater, storage heaters charging, or timed appliances.

Can LED lights cause RCD tripping?

Yes, some LED drivers cause small leakage currents. Quality LEDs are less likely to cause issues.

Should I just hold the RCD switch up?

Never. The RCD is protecting you from a real hazard. Find and fix the cause.

My RCD trips randomly with nothing plugged in - why?

This suggests a wiring fault rather than an appliance fault. You need an electrician.

RCD problems in Devon? Call Grant's Electrical Solutions on 01626 374 059 for same-day fault finding.