Consumer Unit Upgrade — Costs & What to Expect (Milton Keynes 2026)
Updated: May 2026 · By Depth of Light Ltd, Milton Keynes
Replacing a consumer unit (the box previously called a "fuse box") is one of the most common electrical jobs we do in Milton Keynes. Here's what it costs in 2026, what's included, how long it takes, and when you actually need one.
Cost in 2026
- Standard board, up to 12 circuits, full RCBO protection: £450-£700
- RCBO board with AFDDs (BS 7671 Amendment 4 full compliance): £600-£900
- Larger / multi-section / solar-and-EV-ready board: from £900
All pricing includes the EIC (Electrical Installation Certificate), Part P Building Control notification, and any required upgrades to meter tails or earthing. If you need new circuits as part of the swap, those are quoted separately.
How long does it take?
A standard residential consumer unit swap is typically a half-day to full-day job. Power is off for 3-5 hours during the testing and installation phase. We give you 48 hours' notice minimum and try to schedule around your day — first thing in the morning is usually best so the lights are back on by lunch.
What's included
- Supply and fit new consumer unit (your choice of brand — Hager, MK, Wylex, Schneider, Crabtree)
- Every circuit individually protected with an RCBO
- RCD protection on the unit (now redundant when you have RCBOs but still added by some manufacturers)
- Full circuit identification and labelling
- Electrical Installation Certificate (EIC)
- Building Control notification under Part P (you receive a compliance certificate within 30 days)
- 12-month workmanship warranty
- Tidy install — old board removed, area cleaned
Why upgrade?
You probably need to upgrade if your existing board:
- Uses old-style rewireable fuses
- Has only MCBs (no RCD protection)
- Is in a damp, hot or unsafe location
- Has visible scorch marks or trips frequently
- Is needed for adding solar, battery, or EV charging (these almost always need an upgrade)
- Failed an EICR with C1 or C2 codes
RCBOs vs MCB+RCD — what changed
Older boards used a row of MCBs (overcurrent protection) plus one or two RCDs (fault protection) covering groups of circuits. The annoying side effect: when an RCD trips on one fault, it takes out every circuit on that group — your lights, sockets, fridge, freezer all go off together.
Modern RCBOs combine both functions per circuit. One circuit faults, only that circuit trips. Better protection, easier diagnosis, less disruption. We install RCBO-protected boards as standard — no exceptions, no upcharges.
What's BS 7671 Amendment 4?
The current UK wiring regulations. Amendment 4 (April 2026) introduced new requirements for residential consumer units, the most significant being AFDDs (Arc Fault Detection Devices) on certain circuits — particularly bedroom socket circuits and some higher-fire-risk locations. We install AFDDs where required as standard. You can choose to add AFDDs on additional circuits for extra protection.
Solar / EV / battery ready
If you're planning solar, a battery or an EV charger soon, ask us to size the new board with future load in mind. We typically install with 20-30% spare capacity so additions don't need another upgrade. Solar + EV charger + battery all need their own dedicated breakers.
Get a Consumer Unit Quote
Free survey across Milton Keynes and Buckinghamshire — MCS & NAPIT certified.