Consumer Units (Fuse Boxes)

1. Burnt or Melted Components

• Overheating from overloaded circuits
• Loose connections causing arcing
• Visible scorch marks inside the unit

2. Frequent Tripping

• RCD or MCB tripping repeatedly
• Indicates earth fault or overload somewhere on the circuit
• Can also be a faulty breaker itself

3. Outdated Boards

• Old fuse-wire or plastic-bodied units
• No RCD shock protection
• Not compliant with current Amendment 2 to BS 7671

4. Water or Moisture Damage

• Corrosion on busbars and terminals
• Boards installed in damp locations
• Risk of short circuit and electric shock

minor Repairs

• Replace individual faulty MCB or RCD
• Re-tighten loose connections to manufacturer torque
• Replace damaged faceplate or door

moderate Repairs

• Add RCBOs to provide individual circuit shock protection
• Add surge protection device (SPD)
• Replace failed main switch

major Repairs

• Full consumer unit replacement to metal-clad, dual-RCD or all-RCBO design
• Re-label and re-test all circuits
• Add new circuits for EV charger, solar PV or heat pump
• Issue Minor Works or full EIC certificate

When Replacement Is Needed

• Existing unit is plastic, old or non-compliant
• Adding a major new circuit (EV, solar, hot tub)
• After a rewire or major renovation
• EICR identifies the consumer unit as a fault

Installation Steps

1. 1

   Survey & Specify

   • Assess existing circuits and loads
   • Specify metal-clad unit with RCBOs and SPD
   • Notify DNO if isolation of supply is needed
2. 2

   Isolate & Remove

   • Isolate at the main service head
   • Disconnect and remove old unit safely
   • Inspect tails and earthing for upgrade
3. 3

   Install New Unit

   • Mount new metal-clad consumer unit
   • Connect tails, main earth and circuits
   • Label every circuit clearly
4. 4

   Test & Certify

   • Full installation testing per BS 7671
   • Verify RCD trip times and SPD operation
   • Issue certificate and notify Building Control