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BS7909 · BS7671:2018+A2:2022 · 18th Edition

Cable Calcs Done Right For Temporary Power

The only cable calculation tool built specifically for BS7909 temporary electrical installations. Stop wrestling with spreadsheets on site. Get compliant designs in minutes.

⚡ Use the Free Tool ▶ Open the Calculator
BS7909:2023 Compliant
Works offline on site
PDF export with your logo
No install required
£2,250Cost of closest competitor
(CableCalc Level 4)
0Existing tools built
specifically for BS7909
~8,000Estimated BS7909-qualified
engineers in the UK
ExcelWhat 90%+ of engineers
currently use on site
Live Preview

See it working

Real calculations, real compliance checks — running right in your browser. No install, no setup.

app.temppowerpro.co.uk / distribution-board
Design Current
63.4 A
Cable CCC (Derated)
80.0 A
Voltage Drop
1.82%
Zs
0.2980 Ω
PSCC
771 A
Disconnect
OK
CircuitDescriptionBreakermm²Ib (A)Vd%Zs (Ω)PSCCDiscCCPVD ✓
C1 Main Stage Feed C125 35 101.6 1.39% 0.1900 1211 OK OK OK
C2 FOH Mix Position C63 16 45.0 2.14% 0.3540 650 OK OK OK
C3 Catering Village C32 6 34.2 4.12% 0.6800 338 FAIL FAIL FAIL
C4 Lighting Rig C63 16 58.0 2.76% 0.3280 701 OK OK OK
What you get

Everything a temporary
power engineer needs

Built from the ground up for event power — not adapted from software designed for house rewires.

⚡
Single Circuit Calculator
Full BS7671 calculation: CCC, voltage drop, Zs, PSCC, disconnection check. Supports 1Ø and 3Ø, ring finals, thermal insulation, grouping and temperature correction.
Instant results
🗂
Distribution Board Schedules
Design complete multi-board installations. Inline editing, live recalc on every change, phase load bars, and automatic fail highlighting across your entire project.
Multi-board support
🔍
Auto Cable Sizer
Enter your load and constraints — TempPower Pro tests every cable size from 1.5mm² upward and recommends the minimum compliant cable with full comparison table.
Saves hours on site
⚖
Phase Balance Analyser
Visualise L1/L2/L3 loading across all boards. Flags imbalance over 10% per BS7909. One-click auto-balance redistributes single-phase circuits for optimal load sharing.
BS7909 Cl. guidance
✅
Full Compliance Report
One-click scan of every circuit against BS7671 and BS7909. Pass/fail on CCC, volt drop (3% limit), earth fault disconnection, and breaking capacity — with plain English explanations.
Client-ready output
📄
Branded PDF Export
Generate professional calculation documents with your company logo, engineer name, project reference and date. Ready to hand to a client, venue, or local authority.
Your brand, your docs
📊
Max Zs Reference Tables
Full BS7671 Tables 41.3 and 41.4 — Type B, C, and D MCBs for both 0.4s and 5s disconnection times. Plus a live Zs checker so you can instantly validate any circuit.
No more flipping through regs
💾
Save, Load & Cloud Sync
Projects saved to your account and accessible anywhere — desktop, tablet, or phone on site. Export as JSON to share with colleagues or archive for handover documentation.
Pro & Team plans
📱
Works Offline On Site
No signal on the festival field? No problem. TempPower Pro runs entirely in your browser — no app to install, no internet required once loaded. Your calculations stay with you.
Field ready
Simple process

Up and running
in 10 minutes

01
Create your project
Enter your project name, client, engineer and doc reference. Everything appears on your exported PDFs automatically.
Takes 30 seconds
02
Set up your boards
Add your distribution boards with Ze values. Import from a previous project or start fresh — add as many boards as your installation requires.
Unlimited boards on Pro
03
Enter your circuits
Fill in circuit descriptions, loads, cable sizes and lengths. Results calculate instantly as you type — failures turn red immediately.
Live calculation
04
Export & sign off
Run the compliance check, fix any issues flagged, then export your branded PDF calculation pack — ready for client, venue, or LA submission.
Client-ready in minutes
Launch Offer
14-day free trial
on Pro & Team
For the first 100 engineers who sign up. No card required during the trial.
Start 14-Day Free Trial →
What engineers are saying

"Finally something built for how we actually work on events — not a tool designed for domestic installs that we're trying to force into a festival context."

Beta Tester
Event Power Engineer · UK
Why TempPower Pro

The only tool built
for your work

Other tools are adapted from permanent installation software. TempPower Pro was designed from day one for BS7909 temporary power.

Feature TempPower Pro CableCalc BS7671 Excel Spreadsheet
BS7909 specific compliance checks ✓ Built in ✗ None ✗ Manual
Works in browser, no install ✓ Always ✗ Desktop app ~ Depends
Auto cable sizer ✓ Included ✓ Included ✗ Manual
Phase balance analyser ✓ With auto-balance ✗ None ✗ Manual
Branded PDF export ✓ Pro plan ✓ Paid tier ✗ None
Works offline on site ✓ Always ~ Sometimes ✓ Always
Price From £0 — £15/mo £295–£2,250 one-off Free (your time isn't)
Simple pricing

Start free.
Upgrade when ready.

Free tool, always. Upgrade to Pro for branded PDFs, unlimited boards and BS7909 compliance reports. 14-day trial, no card needed.

Free Forever
£0
Try it on your next job. No account needed.
  • Single circuit calculator
  • 1 distribution board
  • BS7671 compliance checks
  • Reference tables
  • Auto cable sizer
  • PDF export (watermarked)
  • Project save / cloud sync
  • Company branding
  • BS7909 compliance report
Use Free Tool →
Pro
£15/mo
Everything you need for professional event power design.
  • Everything in Free
  • Unlimited distribution boards
  • Full BS7909 compliance report
  • Phase balance analyser
  • Branded PDF export (your logo)
  • Project save & cloud sync
  • Max Zs checker
  • Priority email support
  • Team sharing
Start 14-Day Free Trial →
Team
£45/mo
For companies running multiple projects and engineers.
  • Everything in Pro
  • Up to 5 users
  • Shared project library
  • Admin dashboard
  • Custom cable databases
  • Client-facing report branding
  • Phone & email support
  • Early access to new features
Start 14-Day Free Trial →
Enterprise / white-label? [email protected] →
Early Access

Get early access.
Free trial included.

Enter your email and be first to get access when accounts go live. We'll include a 14-day free Pro trial — no card, no commitment.

🔒 No spam. No card. Just early access.
Questions

FAQ

Is TempPower Pro a substitute for a qualified engineer?
No — and it doesn't claim to be. TempPower Pro is a design and calculation aid, not a sign-off document. All temporary electrical installations under BS7909 must be designed, installed, tested and signed off by a competent person as defined under the Electricity at Work Regulations 1989. TempPower Pro helps that competent person do the calculations faster and with fewer errors.
Which standards does it comply with?
TempPower Pro calculations are based on BS7671:2018+A2:2022 (IET 18th Edition Wiring Regulations) and BS7909:2023+A1:2024 (Code of Practice for Temporary Electrical Systems). Cable data is sourced from BS7671 Appendix 4 tables.
Does it work on site without internet?
Yes. Once loaded in your browser, TempPower Pro works entirely offline. Your projects are saved locally in your browser. With a Pro or Team account, you can also sync projects to the cloud for access across devices.
How is this different from CableCalc or similar tools?
CableCalc and similar tools are built for permanent BS7671 installations — domestic, commercial and industrial wiring. TempPower Pro is built specifically for BS7909 temporary installations: it includes BS7909-specific voltage drop limits (3%), phase balance analysis, event-specific circuit types, and is priced for individual engineers rather than large firms.
Can I export a PDF to give to clients or venues?
Yes, on the Pro plan and above. PDFs include your company logo, engineer name, project reference, date, and full circuit schedules with pass/fail results. They're designed to be handed to a client, venue, or local authority as part of a design submission.
Can I cancel at any time?
Yes, absolutely. No minimum term, no cancellation fees. Cancel from your account settings and you'll retain access until the end of your billing period.
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