Morgan Allen: Created page with "= Consumer Unit Replacement Procedure = == Purpose == To safely replace an existing consumer unit with a new unit, ensuring all circuits are correctly reconnected, protected by the appropriate protective devices, and left in a safe working condition. == Procedure == === 1. Confirm The Scope Of Work === * Identify the existing consumer unit and all outgoing circuits. * Check for signs of damage, overheating, or outdated equipment. * Confirm whether the replacement is l..."

2026-06-10T13:47:30Z

Created page with "= Consumer Unit Replacement Procedure = == Purpose == To safely replace an existing consumer unit with a new unit, ensuring all circuits are correctly reconnected, protected by the appropriate protective devices, and left in a safe working condition. == Procedure == === 1. Confirm The Scope Of Work === * Identify the existing consumer unit and all outgoing circuits. * Check for signs of damage, overheating, or outdated equipment. * Confirm whether the replacement is l..."

New page

= Consumer Unit Replacement Procedure =

== Purpose ==
To safely replace an existing consumer unit with a new unit, ensuring all circuits are correctly reconnected, protected by the appropriate protective devices, and left in a safe working condition.

== Procedure ==

=== 1. Confirm The Scope Of Work ===
* Identify the existing consumer unit and all outgoing circuits.
* Check for signs of damage, overheating, or outdated equipment.
* Confirm whether the replacement is like-for-like or an upgrade (e.g. split load to all RCBO).
* Take clear photos of the existing setup before any work starts.

---

=== 2. Isolate The Supply ===
* Follow the JME Safe Isolation Procedure.
* Isolate the incoming supply at the main switch or service cut-out (if authorised).
* Lock off and label the supply.
* Prove dead at the consumer unit using approved test equipment.
* Confirm all circuits are dead before touching any conductors.

---

=== 3. Remove Existing Consumer Unit ===
* Remove cover and identify all outgoing circuits.
* Label cables clearly if not already identified.
* Disconnect outgoing circuits one at a time.
* Inspect all conductors for:
* Damage or overheating
* Brittle insulation
* Loose or poor terminations
* Remove the old consumer unit once fully disconnected.

---

=== 4. Prepare New Consumer Unit ===
* Fix new consumer unit securely in position.
* Ensure there is enough space for safe cable routing and termination.
* Check incoming tails are suitable for reuse or require replacement.
* Prepare all circuit cables for termination.

---

=== 5. Device Layout (MCBs vs RCBOs) ===

==== MCB (Miniature Circuit Breaker) ====
* Provides protection against:
* Overload
* Short circuit
* Typically used where circuits share an RCD (e.g. split load boards).
* Does not detect earth leakage faults on its own.
* Multiple circuits are protected by a single RCD upstream.

==== RCBO (Residual Current Breaker with Overload Protection) ====
* Provides individual protection for each circuit:
* Overload protection
* Short circuit protection
* Earth leakage protection (RCD function built in)
* Each RCBO protects a single circuit independently.
* Reduces nuisance tripping affecting multiple circuits.

==== Neutral Flylead (RCBO Setup) ====
* Most RCBOs require a neutral connection via a flylead.
* The flylead connects the RCBO to the neutral bar in the consumer unit.
* Each circuit has its own neutral directly associated with its RCBO.
* Care must be taken to ensure:
* Correct neutral pairing per circuit
* No cross-connected neutrals between circuits

---

=== 6. Reconnect Circuits ===
* Reconnect circuits one at a time.
* Ensure correct assignment to:
* MCBs (line protection only)
* RCBOs (line + neutral protection per circuit)
* Tighten all terminals securely.
* Keep wiring neat, separated, and under no strain.
* Ensure neutrals are correctly paired (especially with RCBOs and flyleads).

---

=== 7. Reconnect Supply ===
* Double-check all terminations.
* Ensure no exposed conductors remain.
* Fit all covers securely.
* Remove lock-off devices.
* Restore supply and switch on circuits gradually.
* Check for immediate faults or tripping.

---

=== 8. Testing ===
* Carry out required electrical tests:
* Polarity
* Earth continuity
* Insulation resistance (where applicable)
* RCD/RCBO trip testing
* Confirm correct operation of all protective devices.
* Verify each circuit operates independently as expected.
* Record test results where required.

---

=== 9. Final Checks ===
* Confirm all circuits are correctly labelled.
* Ensure consumer unit is tidy, secure, and correctly assembled.
* Check for signs of overheating or abnormal operation.
* Clean work area and remove all waste.
* Explain installation and any changes to the customer.

---

== Common Issues ==
* Damaged or deteriorated cables during changeover
* Incorrect neutral pairing (especially on RCBO boards)
* Mixed up circuits due to poor identification
* Existing faults causing RCD/RCBO trips
* Overcrowded consumer units
* Incorrect device selection (MCB vs RCBO mismatch)

---

== JME Standard ==
All consumer unit replacements must be safely isolated, correctly terminated, appropriately protected using MCBs or RCBOs as required, fully tested, and left in a safe and compliant condition.

Consumer Unit Change Checklist - Revision history