• Electricity flow is called a current.

• The size of the current is determined by the wattage of the lamp.

• Electrical appliances are measured in watts (the higher wattage = more current).

• Pressure in electrical circuits is called voltage or volts.

• 240 volts = common AUS/UK voltage in electrical appliances.

• The measurement of the current-carrying capacity is ampere or amp.

• Electricity resistance is the opposition to the current flow in a circuit.

Electrical problems may come from two areas: supply of electricity; and interference with signals.

Lighting consoles, dimmers, intelligent lights, and LED fixtures are all involved with both 240 volt supply and digital control signals. Lighting technicians more than others need to be aware of these two functional requirements. Lighting frequently runs numerous electric circuits operating at mains voltages, with amperages capable of causing blackouts from overloads, electric shocks, and even fires

Supply of Electricity

Lighting consoles, dimmers, intelligent lights, LED luminaires are usually 240 volt systems. Some equipment may use separate plug in power supplies. If so, be careful that the correct power supply is being used. Too high a voltage will fry the electronics, insufficient power (volts × amps) may end up in an un-scheduled blackout when the supply fails. Occasionally lights operating at 120 volts (for example, USA 1000 watt Par Cans) may be found. Some modern dimmers can control these, or special connector units may be required.

Supply of Electricity

Whether we like it or not (or know it or not) a lot of math goes into lighting design. While it is not necessary to think about it all the time, it is important to have a basic understanding of it.

Note that some lighting instruments are long-throw instruments and others are short-throw instruments. That just means the beams of long-throw instruments tend to reach farther than the beams of short-throw instruments. The beam is the directional projection of light: the actual light coming from the lighting instrument.

The diagram (left) shows a conic beam. One of the most important things on this diagram is the capital ‘B’. The capital ‘B’ is the beam angle. Lighting instruments are identified by their beam angles. The beam angle is the degree of the light that you see on the light’s body. For instance, most ERS Source Fours have a beam angle of 26͒, though some have 36 degrees, 19 degrees, etc. Fresnels and other short throw instruments of beam angles of about 25 degrees to 45 degrees. Long throw instruments have smaller beam angles than short-throw instruments. On the diagram, the line ‘d’ is the distance from the lighting instrument to the surface it is hitting, and the line ‘r’ is half of the beam spread. The angle B is coming from the inside of the lighting instrument, and the circle face of the cone is what is hitting the stage.

Colour is used to create mood and to highlight objects in a production. The positioning of the lights and choice of colour have a strong impact on achieving the required effect and mood.

Watch the video 'Colour mixing' with Lincoln Gidney as he discusses additive and subtractive colour mixing.

TASK:

• Explain why colour is one of the most powerful tools in lighting design and how it is used to convey meaning to the audience.

• Define additive and subtractive colour mixing and identify different production situations when you would use each effect.

• Discuss the different colours being used in the 2 images below and the effect they have