Consumer unit replacement in London — when, why, and how much
If your fuse box is plastic, has rewireable fuses (orange or grey wires sticking out), or no main RCD switch, it's almost certainly pre-2015 and below current UK safety standards. Here's how to know if it's time, what gets installed instead, and what it costs.
What's wrong with old consumer units?
The 17th Edition Wiring Regulations (2008) required RCD protection on socket circuits. The 18th Edition (2018, amended 2022) goes further — recommending an RCBO (combined RCD + breaker) on every circuit, not just sockets.
An old consumer unit typically has:
- Plastic enclosure (which can deform and melt during a fault)
- Rewireable or BS 1361 cartridge fuses (slow to detect faults vs modern breakers)
- No RCD or just one main RCD covering everything (so a fault on the kitchen circuit also kills your fridge / lights upstairs)
- No surge protection
An 18th Edition consumer unit has:
- Steel enclosure (won't melt or fail in a fault)
- An RCBO per circuit (only the affected circuit trips, the rest stay on)
- Optional Type 2 surge protection (recommended for areas with frequent power cuts or storms)
- Properly labelled circuits
- SPD (Surge Protection Device) where appropriate
When you must replace it
Hard triggers — replace immediately:
- Visible damage, scorch marks, or melting on the unit
- EICR returned C1 or C2 with "consumer unit not compliant"
- Selling the property and the buyer's surveyor flags it
- Before letting a property as a landlord (regulations require RCD protection)
- Adding new circuits (EV charger, electric shower, kitchen extension) that the old unit can't safely accommodate
Soft triggers — plan to replace within 12 months:
- Plastic enclosure (cosmetic update + safety improvement)
- No main RCD switch
- Frequent nuisance trips (often = old RCD wearing out)
- Selling within the next 1-3 years
What it costs in London
| Replacement type | Price | Time on site |
|---|---|---|
| Standard 8-way (most homes) | £695 | 3-4 hours |
| Larger 12-16 way | £795-£895 | 4-5 hours |
| Add Type 2 SPD (surge protection) | +£135 | Included if done at install |
| Add Type 2 RCD for outdoor circuits | +£85 | Included if needed |
All prices include same-day NICEIC certificate and Building Control notification under Part P.
What happens on install day
- Power off — main switch off, then incomer fuse pulled if needed (we coordinate with UKPN if pulling the main fuse — usually unnecessary for a like-for-like replacement)
- Old unit removed — typically 30-45 minutes. Cables tagged.
- New unit fitted — RCBOs allocated per circuit, surge device fitted, properly earthed
- Power back on per circuit — instrument tested for polarity, earth-loop impedance, RCD ramp test, insulation resistance
- Labelled and signed off — every circuit clearly labelled, certificate emailed within 24 hours
Total power off time: usually 2-3 hours. We often work in stages so the fridge stays on. Outside that, you can use the property normally.
What we leave you with
- NICEIC Electrical Installation Certificate (PDF + paper)
- Building Control notification (we file under Part P automatically)
- Schematic of which circuit goes where
- 10-year guarantee on workmanship
- Photos of "before" and "after" for your records
Quick start
Send us a photo of your current consumer unit and we'll tell you immediately whether it needs replacing and quote the right size. WhatsApp 07399 181060 or call 020 3355 7549.
"Need an electrician right now?"
SwiftVolt — 24/7 NICEIC-accredited London electricians. 30-minute callback target.
📞 Call 020 3355 7549 Free Priority ClubCommon questions
Will the power be off all day?
No — typically 2-3 hours total. We work in stages so essential things (fridge, freezer) can be turned back on partway through if it's a long job.
Do I need to be there for the install?
Yes — someone needs to be at the property to provide access and to be present when power is off. The whole job is usually a half-day.
What if my circuit cables are old and need re-tailing?
We sometimes find old cables that have insulation degradation at the consumer-unit end. We'll re-tail (replace the last few inches of cable) on those circuits as part of the work — included in the price unless major.