Event Power for Crew

01Volts, amps and watts

Three numbers describe every supply and every piece of kit. If you can turn one into the others you can plan the power for any event with a calculator. Think of electricity as water in a pipe.

• Volts: the push. 230 V between a live and neutral in South Africa (the old "220 V" figure was changed to 230 V in the national standard in the 2000s; your kit does not care). 400 V between any two lives on a three-phase supply.
• Amps: the flow. A 16 A breaker lets 16 A through, then trips. Everything on that circuit shares those 16 A.
• Watts: the work. A 1 000 W light at 230 V pulls 4.3 A. A 2 000 W tea urn pulls 8.7 A. Two urns on one 16 A circuit is already 17.4 A: trip.
• kW and kVA: 1 kW = 1 000 W. Generators are rated in kVA; multiply by 0.8 to get the real kW you can use (Lesson 7).

02Single-phase and three-phase

Mains power is alternating current (AC): it swings positive and negative 50 times a second (50 Hz). A single-phase supply is one of those swings on one live wire. A three-phase supply is three swings on three live wires, each a third of a cycle behind the last. Big kit and big sites use three-phase because it carries three times the power on cables that are not three times the size.

What this means on site

• The generator and the venue's big outlet are three-phase (red plug, 5 pins).
• Almost everything you plug in is single-phase (blue Commando or ordinary 3-pin).
• Between the two sits a distro, which splits three-phase into single-phase outlets. That is Lesson 4.
• You never touch what is inside a plug, a distro or a board. If a lead has bare wire or a loose pin, it is out of service, tagged, and goes to an electrician.

03Plugs and sockets you will meet

South African event power uses two families: the ordinary 3-pin round plug for the last metre, and the industrial CEE "Commando" plugs for everything upstream. Colour tells you the voltage. Size tells you the current. Pin count tells you single or three-phase. You can only plug a connector into its own matching socket, which is the point: the system protects you from the common mistakes.

In the B&W kit: 63 A and 32 A five-core trailing leads, 16 A blue Commando extensions, and standard 3-pin extension leads for the last metre.

04The distro chain

A distro (distribution box) takes one big supply in and gives you several smaller, protected supplies out. Every outlet has its own breaker, so one overloaded speaker trips one outlet, not the whole event. On site, the chain always runs big to small.

In the B&W kit: 63 A three-phase distros with four 32 A outputs, and 32 A distros with an in and a link-out that chain to the next distro.

Setting up the chain

1. Every breaker on every distro off. Earth leakage units reset.
2. Run the 63 A lead from the generator (or venue outlet) to the 63 A distro. Lay it where nobody walks or drives; ramp it where they must.
3. Run 32 A leads from the 63 A distro to each 32 A distro. One per area: stage, lighting, bar, catering. Keep the leads short; long runs lose voltage.
4. Run 16 A Commando or 3-pin extensions from the 32 A distros to the kit. One lead per speaker stack where you can. No daisy-chained extension leads on sound.
5. Walk the whole chain once with nothing on. Check every plug is fully home and every lead is off the ground where it crosses water.
6. Power up from the source outwards: generator → 63 A main → 63 A outputs → each 32 A distro main → its outlets → kit, one area at a time. Listen for the earth leakage. If it trips, the fault is on whatever you just switched on.

05Load and phase balance

Two sums before every event: does each cable stay under 80% of its breaker, and are the three phases carrying roughly the same load? An unbalanced three-phase supply trips one phase early while the other two sit idle, and it makes a generator run badly.

How to balance

• A 32 A distro's 16 A outlets are already split across L1, L2 and L3 (the label on each outlet, or the layout, tells you which). Spread your heavy items across all three.
• Put the heaters (urns, slush machines, heat lamps) on their own outlets and their own phase. They are the biggest single loads at a corporate event.
• Sound on one phase, lighting on another, catering on the third is a good default for a small event with one 32 A distro.
• Write it down. A taped label on each outlet ("L2 · subs") saves the next person guessing.

06Breakers, earth leakage and leads

Everything between the source and the kit exists to break the circuit before a person or a cable gets hurt. Learn what each device does so you know what it means when one trips.

Extension leads: the three rules

1. Unroll cable drums fully. A coiled drum carrying load is a heater. The rating on the drum halves when it is wound.
2. One lead, one job. No lead into a lead into a multiplug. Every join is a weak point, a trip hazard and a place water gets in.
3. Short runs for big loads. Voltage drops along a cable. 50 m of 2.5 mm² lead feeding a 3 kW load loses enough voltage that amplifiers clip early and heaters run cold. Move the distro closer instead of running the lead longer.

07Generators

When there is no mains, or the venue's supply is too small, the generator is your power station. Treat it as the most important piece of kit on site: if it stops, everything stops.

In the B&W kit: a 32 kVA three-phase diesel generator with a 63 A five-pin outlet.

kVA, kW and headroom

• Generators are rated in kVA. Multiply by 0.8 to get usable kW: a 32 kVA set gives about 25 kW. A 20 kVA set gives 16 kW.
• Never run a generator flat out. Plan for 70% load: 32 kVA → about 18 kW of kit. 20 kVA → about 11 kW.
• Motors and amplifiers pull a surge when they start. Switch kit on in stages, biggest first, with a few seconds between.
• Too little load is also bad for a diesel. Under 30% load for hours glazes the engine. If the event is tiny, hire a smaller set.

Fuel figures are planning estimates. Check the set's own plate and fill before every event; an 8-hour corporate day on a 32 kVA set is roughly 40 to 50 litres.

Placing the generator

Start-up and shutdown

1. Fuel, oil and coolant checked. Earth spike connected (the hire company or electrician does this; you confirm it is there).
2. Main output breaker off. Start the engine. Let it run 3 to 5 minutes with no load.
3. Main breaker on. Then the 63 A distro, then each 32 A distro, then kit, one area at a time.
4. Shutdown in reverse: kit off, distros off, main breaker off, let the engine run 2 to 3 minutes unloaded, then stop it. Never stop a diesel under load.
5. Refuel only with the engine off and cool. Log the hours.

0863 A vs 32 A vs 16 A: what goes where

The number on the plug is the most current that cable and socket may carry. Here is the same rule from the other direction: how much kit each supply can feed, and which supply each job needs.

09Safety, and where crew stop

Event power kills people every year, almost always through water, damaged leads or someone opening something they should not. The rules are short because they have to be followed every time.

Every event

• Visual check of every lead as you run it: cuts, crushed sections, bent pins, loose cable glands. Damaged means tagged and out.
• All plugs fully home. A half-inserted Commando plug arcs and melts.
• Leads off wet ground. Crossings ramped or flown. Nothing under a vehicle route.
• Distros off the floor on a stand or case, lids closed, out of the rain, never inside a tent wall where a guest leans.
• Water and power do not meet: no distro near the bar sink, the ice bath or the sprinkler. Outdoor gear is rated IP44 or better, or it is under cover.
• Know where the main breaker and the generator stop button are. Everyone on crew knows. Tell the venue manager.
• Earplugs, gloves for hot lamps, no jewellery on hands when handling leads.

Fast fault-finding

Before you leave the warehouse

• Count: 63 A leads, 32 A leads, 16 A extensions, 3-pin extensions, distros, ramps, gaffer, earth spike and hammer (generator jobs), tags and marker
• Test every distro: main on, earth leakage test button, every outlet live
• Generator: fuel full, hours logged, extinguisher and drip tray on the truck
• Spares: one of every lead type