Free design tool for UK van conversions
Your campervan electrical system, designed in 5 minutes.
Tell us what you'll run in your van. We'll calculate your battery, solar, inverter, every cable size and every fuse — and give you a complete wiring diagram, built to UK standards and explained in plain English.
Free · No experience needed · Based on BS 7671 & manufacturer guidance
Not a number. A complete design.
Most calculators give you a battery size and wish you luck. Roam Wired gives you the whole system: an interactive wiring diagram, a cable schedule, a fuse schedule, a parts list, and step-by-step installation notes — every value traceable to a real calculation.
Three steps. No jargon.
You don't need to know what an amp-hour is. Answer plain questions, get a professional design.
Pick your appliances
Fridge, lights, laptop, kettle — tick what you’ll run in your van and how long you’ll use it each day.
Choose your preferences
Battery type, budget, solar, off-grid time. We handle every calculation behind the scenes.
Get your design report
Wiring diagram, cable & fuse schedules, parts list, and install notes — free, in about 5 minutes.
Calculated, not guessed.
Forum threads disagree. YouTube comments argue. Your design shouldn't depend on whichever opinion you read last.
Built on real standards
Every recommendation follows Victron’s Wiring Unlimited, Blue Sea / ABYC guidance, and BS 7671 Section 721 — the UK regulations for electrical installations in caravans and motor caravans.
Show-the-maths transparency
Click any component or cable in your diagram and see the exact calculation behind it. No black boxes, no "trust us".
Honest about limits
Anything involving 230V mains, we’ll tell you plainly: have it done or signed off by a qualified electrician. Your safety outranks our convenience.
Your free design report includes:
A campervan electrical design like this costs £150–£300 from a professional designer. Yours is free.
Interactive wiring diagram
Every component and cable in your system, laid out and connected.
Cable schedule
The exact cross-section for every run, sized for current and voltage drop.
Fuse schedule
Every fuse rating calculated to protect its cable — including the main battery fuse.
Full parts list with UK prices
Everything you need to buy, from the battery down to the last fuse holder.
Installation notes in build order
What to install first, what to connect last, and what to double-check.
Every assumption listed and sourced
See exactly what we assumed and where each rule comes from.
Questions, answered.
Is it actually free?
Yes. The full design — wiring diagram, cable schedule, fuse schedule, parts list and installation notes — is free. We earn a small commission if you buy parts through our links, at no extra cost to you. That keeps the tool free for everyone.
Do I need any electrical experience?
No. The tool asks plain questions — what appliances you’ll use and for how long — and handles all the calculations. Every recommendation is explained in plain English, and anything that legally or practically needs a qualified electrician (like 230V mains work) is clearly flagged.
Does it work for my van?
Yes. The design principles are identical across all panel vans and motorhomes — Mercedes Sprinter, Ford Transit, VW Crafter, Fiat Ducato, Renault Master, Vauxhall Movano and others. The design is based on your appliances and usage, not the badge on the bonnet.
Can I trust the numbers?
Every value is traceable. Cable sizes satisfy both current capacity and voltage-drop limits, fuses are sized to protect their cables, and the rules come from Victron’s Wiring Unlimited, Blue Sea / ABYC guidance and BS 7671 Section 721. Click any component in your diagram to see the actual calculation.
Go deeper
Guides for every stage of your electrical build.
Flexible solar panels for campervans: do they handle roof curves, heat, and vibration? Real-world durability and performance data.
Peak sun hours data for UK regions and European destinations. Essential for sizing your campervan solar system accurately.
Complete guide to Mercedes Sprinter campervan electrics. Smart alternator, battery locations, solar setup, and wiring for Sprinter conversions.
Stop second-guessing your build.
Five minutes from now you could have your complete electrical design — every wire, every fuse, every part.
Get my free designFree · No sign-up to start · Takes about 5 minutes