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 electricians 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 for UK temporary electrical and HVAC planning.
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. Treat it as a pre-check for the conversation or job file. 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 clearance to switch on.
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 checked by a qualified electrician before use.
Next tools in this workflow
See job flows
Calculator · 110V / site transformer
110V transformer heater check
Check whether a 110V site transformer can realistically power temporary heaters, dehumidifiers, fans or drying kit without overload or unacceptable voltage drop.
Calculator · RCD / earth leakage
RCD leakage budget
Estimate cumulative leakage from compressors, dehumidifiers, portable AC, heaters, pumps and long wet leads before stacking everything behind one RCD.
Calculator · generator / kVA
Generator kVA + start current
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
Three-phase load balancer
Allocate single-phase heaters, dehumidifiers, fans and portable AC units across L1/L2/L3 to reduce imbalance and nuisance trips.