Ask Siri.
Get Answers.
Voice-powered building regulations, cable sizing calculators, and fault-finding guides — all running offline on your iPhone or iPad. Built for the UK's 230,000+ electricians, 150,000 Gas Safe engineers, and 150,000+ plumbers. Your hands are dirty, you're up a ladder, and you need to check a regulation. Just ask.
£19.99/year · 7-day free trial · No data collected
See It in Action
Real screenshots from Auvi Trade on iPhone.
Home
Cable Sizing
Calculators
Reference
Settings
“Hey Siri, ask
Auvi Trade…”
Your hands are covered in grease. You're holding a cable. You're wedged in a ceiling void. Just talk. Siri routes your question to Auvi Trade, which answers from the Approved Documents — completely hands-free, completely offline.
- Voice-activated — no need to touch the screen
- Works in airplane mode — no internet needed
- Answers in seconds from on-device models
- References regulation numbers in every answer
Hands-Free
Regulation Answers.
Type or speak your question — Auvi Trade searches the Approved Documents and explains the answer in plain English, with the regulation reference so you can quote it to Building Control.
- On-device speech recognition — nothing leaves your phone
- Plain-English answers with regulation references
- Works for electricians, plumbers, and gas engineers
Cable Sizing.
From First Principles.
Every calculator is derived from physics and engineering — conductor resistivity, cross-sectional area, thermal limits, and installation methods. Not copied tables. This means calculations are always based on verifiable science, not someone else's intellectual property.
- Cable current capacity from conductor physics
- Voltage drop: V = I × R × L (Ohm's law)
- Zs = Ze + (R1 + R2) with pass/fail indication
- Maximum demand, pipe sizing, gas pipe sizing, heat loss
Every Approved Document.
In Your Pocket.
Full text of Parts P, G, J, B, and L — searchable, indexed, and cross-referenced. Published by HM Government under the Open Government Licence v3.0. No need to carry the books on site.
- Part P — Electrical Safety in Dwellings
- Part G — Sanitation, Hot Water Safety
- Part J — Combustion Appliances & Fuel Storage
- Parts B & L — Fire Safety, Energy Conservation
- Full-text search across all documents
No Data Collected.
No Exceptions.
Same privacy philosophy as Auvi. Everything runs on your device. No accounts, no analytics, no tracking, no cloud. Apple verified: “No Data Collected.” Your calculations, your questions, your job sites — all stay on your phone.
- Works in airplane mode — everything on-device
- No sign-up, no account, no email required
- Your job site data stays on your device, always
Three Steps. On Any Job.
Download
Install Auvi Trade from the App Store. A one-time download prepares all reference content and on-device models — about 500 MB.
Ask a Question
“Hey Siri, ask Auvi Trade…” or type your question. Voice works when your hands are dirty, wet, or gloved.
Get the Answer
Plain-English answer with the regulation reference. Run a calculation, browse the Approved Documents, or check a decision tree.
Built for the Job Site.
Calculators, decision trees, visual references, and fault-finding guides — all offline, all in one app.
“Is this work notifiable?” — interactive flowchart tells you in seconds
ElectricalInteractive zone diagram with IP ratings and permitted equipment
ElectricalSupply assessment, cable design, earthing, testing, smart charger requirements
ElectricalCable and pipe penetration requirements for fire-separating elements
All TradesGuided flowcharts for RCD tripping, no power, partial loss of supply
ElectricalEarth conductor sizing using the adiabatic equation
ElectricalLoading units method for domestic hot and cold water systems
PlumbingPressure drop method for domestic gas installations
GasRoom-by-room heat loss for heating system design
Gas / HeatingSave calculations, export results, keep records of your work
All TradesWill be updated for BS 7671 Amendment 4 (April 2026) — batteries, PoE, ICT earthing
ElectricalEverything works without internet. Basements, voids, building sites — no signal needed
All TradesLess Than Breakfast for the Crew.
Reference books cost a fortune and stay on the shelf. Auvi Trade costs less than a coffee from the van.
| Resource | Cost | Type | Portable |
|---|---|---|---|
| BS 7671 (18th Ed.) | £90 | Book | Heavy |
| IET On-Site Guide | £40 | Book | |
| IET Wiring Matters App | £35/yr | Subscription | Phone |
| Day rate lost to looking things up | £200–400 | Time | — |
| Auvi Trade | £19.99/yr | Annual | Always with you |
Auvi Trade does not reproduce BS 7671 or IET publication content. Calculations are from first principles; reference content is from Approved Documents (Crown Copyright, OGL v3.0).
Works Where You Do.
On a Ladder
Voice-activated — no need to climb down
In a Ceiling Void
Works offline, even where the Wi-Fi doesn't reach
At the Consumer Unit
Quick cable sizing and Zs checks on site
On a Gas Job
Pipe sizing and flue clearance checks instantly
In the Van
Check regulations before you start the job
During an Inspection
Quote the exact regulation to Building Control
Simple Pricing. Everything Included.
No tiers. No in-app purchases. Every feature, every calculator, every Approved Document — one plan, full access.
Auvi Trade
per year · 7-day free trial · Cancel any time.
7-Day Free Trial- Siri integration — hands-free voice Q&A
- All calculators (cable sizing, voltage drop, Zs, max demand, pipe sizing, gas pipe, heat loss)
- Searchable Approved Documents (Parts P, G, J, B, L)
- Part P notifiable work decision tree
- Bathroom zones interactive diagram
- EV charger installation checklist
- Fire stopping reference (Part B)
- Fault-finding guided flowcharts
- CPC sizing (adiabatic equation)
- Save & export calculations
- 100% offline — no internet needed
- No data collected. Ever.
- BS 7671 Amendment 4 updates coming 2026
All purchases through Apple via the App Store.
Payment charged to your Apple ID. Auto-renews at £19.99/year unless cancelled at least 24 hours before renewal. Terms · Privacy
Frequently Asked Questions
Does it work offline?
Yes. All reference content, calculators, and the voice Q&A feature run entirely on your device. No internet connection is needed after the initial download. The optional AI model (~1 GB) is downloaded once and then runs locally.
Does it include BS 7671 content?
Auvi Trade does not reproduce any BS 7671 text, tables, or diagrams — these are copyrighted by the IET and BSI. Instead, the app references BS 7671 regulation numbers and provides the full text of the Approved Documents, published by HM Government under the Open Government Licence v3.0. Calculations are derived from physics and engineering first principles, not from BS 7671 tables.
Which UK nations does it cover?
England & Wales, Scotland, and Northern Ireland. Each nation has its own regulatory framework — Approved Documents, Technical Handbooks, and Technical Booklets respectively. The app updates its content, terminology, and processes when you switch nation.
Is my data collected or shared?
No. Auvi Trade collects no data whatsoever. No analytics, no tracking, no cloud storage, no accounts. The App Store privacy label confirms “No Data Collected”. All speech recognition and AI processing happens on your device.
Will it be updated for Amendment 4?
Yes. BS 7671 Amendment 4 publishes on 15 April 2026 and becomes mandatory from October 2026. Auvi Trade will be updated to reflect the new requirements, including new chapters on battery storage, Power over Ethernet, ICT functional earthing, and revised medical locations.
How are the calculations derived?
All calculations are derived from physics and engineering first principles — conductor resistivity, cross-sectional area, insulation thermal limits, and installation method heat dissipation — using data from cable manufacturer datasheets. MCB trip characteristics use the EN 60898 standard. No copyrighted BS 7671 tables are reproduced.
Building Regs. In Your Pocket.
Auvi Trade is available now on the App Store. From £19.99/year with a 7-day free trial. No data collected. Built for UK tradespeople who need answers on site.
Download on the App StoreRequires iPhone or iPad · iOS 17 or later · £19.99/year · 7-day free trial