A gallery, a stage and a streaming rack all arrive with a list of kit and a vague idea of the supply. This calculator turns the list into a current, shows how much of the supply it uses and, on three phase, suggests how to spread the load across L1, L2 and L3.
How to use it
Pick the supply the venue or power company has offered. Edit the kit list: item, quantity and watts each. The example rows are typical of an event gallery and are only there to show the layout, so replace them with the figures from the equipment labels or data sheets. Leave the power factor at 0.9 unless you have better figures for your kit.
On a single-phase supply you get the total current and the percentage of the rating. On three phase you also get a suggested split, which puts the biggest items on the least loaded phase first. The warning appears above 80% of the rating, because a gallery runs for hours and a supply near its limit leaves nothing for the things you forgot.
What it does not do
It is planning maths. Temporary power at events must be designed, installed and checked by a competent person working to BS 7909. Cable size and length, protection, shared outlets and the venue's real supply all sit outside this tool.
How it works
Total load is the sum of quantity x watts for every row. Current = watts / (230 x power factor). The default power factor is 0.9, a planning figure for mixed switch-mode equipment. If your figures are in VA rather than watts, set it to 1.
The percentage of rating is the current divided by the supply rating. For single-phase supplies of 13 A, 16 A and 32 A, the whole load sits on one phase. For three-phase supplies of 32 A, 63 A and 125 A, the rating is per phase, and the load is split across L1, L2 and L3.
The split is a greedy allocation: every unit of equipment is sorted from largest to smallest, and each is placed on the phase with the lowest load so far. It balances watts, not a real distribution plan, and it does not group items by where they sit in the room. Equipment with several outlets from one source may need to stay on one phase.
The 80% warning is this tool's own planning margin for loads that run for hours. It is not a figure from a standard. Connector ratings follow BS 1363 for the 13 A plug and IEC 60309 for the industrial connectors. The code of practice for temporary systems is BS 7909. Follow it and your competent person's assessment, not this page.
Rather we did the paperwork?
Send the client brief and floorplan to Production Office and get back the kit list, signal flow, crew plan and schedule, checked by a broadcast engineer, with nothing of ours on it.