Temporary electrical load calculator

Check temporary kit loads before anyone plugs in.

For temporary heaters, dehumidifiers, fans and portable AC on UK supplies. Start with the job, check visible stop flags, then keep the load maths and handoff note with the site team.

Planning tool only. Not an electrical inspection, certificate or permission to run equipment. If labels, circuits, plugs or leads are unclear, stop and ask a competent person.

Stop firstWarm plugs, daisy chains, wet routes and coiled reels stay visible.
Maths nextWatts, amps and warning margins remain the source of truth.
HandoffKeep a route note, evidence pack and schedule with the job.
EXAMPLE ROUTEFRZ-JOB-01
front deskSTARTroute the job
schedule10.4A80% warning point
handoffAMBERstagger one load
Comms cabinet700 W = 3.04 A
Reception heater2000 W = 8.70 A
Same circuit11.74 A / 13 A
ROUTE

Above the planning warning point. Keep must-run load on, stagger the heater, capture lead/socket evidence and ask a competent person if the circuit is not confirmed.

Quick load check

If you only need the numbers, run the calculator here.

Enter the kit, socket or circuit rating and any extension-lead issues. The result gives total amps, warning margin and cable flags. For a messy job, start with the router and build the full handoff pack.

1. Route the job.

Heating, drying, cooling, extension lead concern or post-trip review.

2. Confirm facts.

Use equipment labels, socket groups, lead ratings and visible cable-route evidence.

3. Schedule the load.

Separate must-run equipment from loads that can cycle or wait.

Quick load check

Enter the socket or circuit rating and the kit that might run at the same time. Use this as a load check only — not as an electrical inspection.

Use the watts or amps printed on the equipment label. For portable AC, use input power — not BTU cooling output.

Photo note: if you have a photo of the consumer unit or equipment label, use it to read the visible circuit rating or watts/amps. Nothing is uploaded here; if you are unsure, send the photo to a competent person.
Readiness desk

Use the right check for the job in front of you.

See all checks
Core calculator

Temporary kit load check

Add heaters, dehumidifiers, fans and portable AC together, then see total amps, spare margin, daily kWh and cable red flags.

amps + cable risk
Step-by-step plan

Guided setup assistant

Answer a few questions about the job, supply and kit, then get a staged load plan with stop points and a copyable handoff summary.

staged handoff
Agentic front desk

Start job router

Route a temporary heating, drying, cooling or trip job to the right evidence, circuit, schedule and supplier handoff step without hiding the load maths.

router + handoff
Trip assistant

Breaker trip triage assistant

Add same-time loads, trip symptoms and cable red flags to see whether the setup looks like overload, RCD trouble or a stop-and-ask condition.

trip + red flags
Socket groups

Circuit mapping helper

Record a breaker/lamp test so unknown sockets stay out of the split plan until the circuit is actually confirmed.

confirmed circuits
Mobile evidence

Guided evidence capture

Use phone-camera evidence slots for labels, plugs, leads, cable routes and breaker labels, then build a cautious handoff pack without inspection claims.

5 photo slots
Run-time planner

Load schedule / stagger planner

Separate must-run load from cycling or waiting loads so temporary heaters, drying kit, fans and AC do not all run together on one confirmed circuit.

stagger plan
UK plug load

3 kW / 13 A plug checker

Check how close a 3 kW heater is to a 13 amp plug/socket once voltage, other load, run time and extension-lead risk are counted.

13 A edge case
Separate supplies

Circuit split planner

Place heaters, dryers and fans across known separate supplies so one socket or circuit is not carrying the whole temporary load.

separate circuits
Leaks and damp rooms

Drying kit load checker

Add dehumidifiers, air movers and background heaters before they run all day, then check amps, kWh and warning margin.

dehumidifiers + fans
AC and fans

Portable cooling load checker

Check portable AC input watts, cooling fans and existing same-socket equipment before adding more load to a hot room.

AC input watts
Heater count

Electric heater count planner

Work out how many equal-sized electric heaters fit on one or more selected supplies before the delivery turns up.

13 A / 16 A / 32 A
Cable red flags

Extension lead risk checker

Check lead rating, coiled reels, adaptor chains, wet routes and traffic routes before high-load temporary equipment runs for hours.

reels + adaptors
Supplier message

Temporary hire brief builder

Build a copyable hire-supplier note with site type, supply rating, equipment watts and the checks needed before delivery.

copyable brief
kWh and tariff

Running cost estimator

Estimate amps while running, daily kWh and rough electricity cost from the equipment input watts, quantity, run time and tariff.

kWh/day + £
Label reader

Equipment label reader

Upload a rating-label photo, extract visible volts, watts and amps, then confirm the numbers manually.

optional label read

When temporary kit can overload the electrics

Use this when heaters, dryers or portable AC are needed today, but nobody is sure what the sockets can take or which items can run together.

Boiler down / clinic too cold.

Route the job, check the 3 kW edge case, then schedule heaters rather than overlapping everything.

Leak or damp room.

Add dehumidifiers, air movers and background heat, then capture lead and route evidence.

Hot office or server room.

Check portable AC, fans and existing must-run equipment before plugging in more cooling.