Plan circuits by duty, not just by socket count
Separate continuous heaters, compressor loads, pumps and general tools so one fault or overload does not take the whole setup down.
Electrical calculator · temporary DB / distribution board / circuit planning
Temporary Distribution Board Planner
Lay out a temporary board for heaters, drying equipment, fans, portable AC and lighting, with circuit groups and notes.
For competent persons planning temporary distribution, not for DIY live work.
Field notes
Field notes for Temporary DB planner
Practical checks to run before this calculator result turns into a site decision.
Leave spare capacity where the job will change
Drying and event sites evolve. A small amount of planned headroom reduces unsafe last-minute additions.
Make the board understandable
A temporary DB should have a clear schedule, circuit labels and notes on what each outlet supplies.
FAQ
Temporary DB planner FAQ
Short answers written for UK temporary electrical and HVAC planning work.
What is the Temporary DB planner used for?
Lay out a temporary board for heaters, drying equipment, fans, portable AC and lighting, with circuit groups and notes. It is mainly for temporary HVAC, drying, cooling and site-power planning, especially where a quick pre-check is needed before selecting equipment or changing a temporary setup.
Can this replace BS 7671 design, inspection or testing?
No. It is a competent-person planning aid only. Final decisions still need current BS 7671 requirements, manufacturer data, inspection, testing, risk assessment and the actual site conditions.
What should I verify before acting on the result?
Check supply rating, protective device rating, cable length, voltage drop, start current, phase balance and the condition of temporary leads or distribution boards. If any assumption is uncertain, use the result as a prompt to investigate rather than as permission to energise.
What does an amber or red result usually mean?
It normally means the margin is weak, an assumption is missing, or the load should be split, staged, moved closer to the supply, reduced or reviewed by a competent electrician before use.
Next tools in this workflow
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Size a generator for portable AC, dehumidifiers, fans and heaters with a start-current allowance rather than only running watts.
Calculator · three-phase / phase balance
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