Attached or detached — SWA submains from house CU to a sub-board with its own RCBO bank, LED batten lighting, double-socket banks, 16A commando outlets for workshops, EV charger integration. From £380 + VAT @ 20%.
07889 334849 · Dan Stevens
NAPIT
CHAS
City & Guilds
TrustMark
Part P
BS 7671A garage submain is the wrong job to under-spec. Cable size depends on both load and distance — not just one. We calculate volt-drop on the actual route and pick a cable that runs cool, lasts decades, and leaves headroom for future loads (typically the EV charger).
Single lighting circuit, a couple of double-socket points, no heavy loads. Sub-board with 2–4 way RCBO bank.
Multiple socket circuits, LED battens, EV charger on its own way, light power tools. Sub-board with 4–6 way RCBO bank.
16A commando outlet, welder, compressor, EV charger, full bench. Larger sub-board with 6–10 way RCBO bank.
Light commercial use, three-phase machines, multiple EV chargers, large compressors. Designed and certified to BS 7671.
Real DS Electrical install — LED batten lighting and clean cable routing.
Whether it’s a single lighting circuit in an attached garage or a 10mm² SWA submain to a fully kitted detached workshop, the standard is the same. Compliant cable, correct RCBO, sub-board where needed, full test pack, Part P notification.
Steel-wire armoured, glanded both ends, buried at depth or surface-clipped. Never T&E for submain runs.
Full-RCBO consumer unit at the garage end. One RCBO per circuit. Faults isolate cleanly.
5ft battens for proper workshop-grade light. Two-way switched at door and bench typical.
BS EN 60309 blue 16A on dedicated RCBO. Welders, compressors, plasma cutters — no excuses.
Type A RCBO at the sub-board, sized into the submain spec. One install, two outcomes.
Electrical Installation Certificate, Part P notification lodged via NAPIT. Both by email within 7 days.
Final price depends on attached vs detached, dig length, sub-board size, fitting count and whether an EV charger is part of the same install. Survey is free; written quote is fixed. Read the disclaimer below the cards before assuming.
Most of our garage installs combine a SWA submain, a sub-board, LED workshop lighting and an EV charger into one visit. We design the submain to leave headroom for future loads — so you don’t pay twice when you add the next circuit.
It depends on the maximum demand and the run length. For a typical lightly loaded detached garage (lights + a couple of socket circuits) within around 20 metres of the house, 4mm² SWA on a 32A circuit is usually fine. For a workshop with heavier loads — compressor, welder, EV charger, full bench of sockets — 6mm² or 10mm² SWA on 40A or 63A is more typical. Volt-drop is the deciding factor on long runs. We calculate it from the actual route, not assumed.
For anything beyond a single lighting + sockets circuit, yes. A small sub-board (or sub consumer unit) at the garage end of the SWA submain lets each circuit have its own RCBO — one for lights, one for sockets, one for the EV charger and so on. Faults are isolated and the rest of the garage stays running. We use Wylex, Crabtree or Hager sub-boards depending on what the existing house CU is matched to.
Yes — it’s the most efficient way. If we’re running a SWA submain to a sub-board anyway, sizing it to also feed a 32A EV charger is usually only a small uplift in cable cost. The EV charger sits on its own Type A RCBO at the sub-board (BS 7671 requires Type A on EV circuits, never Type B). Talk to us at the survey and we’ll spec a single combined install rather than two separate visits.
Standard for a working workshop. A 16A blue commando socket-outlet (BS EN 60309) gives you a high-integrity connection for compressors, welders, plasma cutters, large grinders and proper site equipment. Wired on its own dedicated circuit with the right RCBO and earth-fault loop impedance, it’ll run a 16A welder all day. We can fit one or several depending on layout, and we’ll talk through whether single-phase 16A is enough or if you need three-phase.
Adding new circuits is always notifiable. Like-for-like replacements (e.g. swapping a tired light fitting on an existing circuit) generally aren’t. We notify automatically through our NAPIT registration; you don’t need to apply separately. Every job ends with an Electrical Installation Certificate or Minor Works Certificate plus the NAPIT compliance certificate logged on the national database. Accepted by insurers, mortgage lenders and surveyors.
If an EV charger or workshop is on the horizon, get the cable specced once for both — far cheaper than two separate visits. Free survey, fixed quote, NAPIT certified.
07889 334849