The load placed on each dimmer gang is based on the number of lamps on the connected circuit. The load is measured in Watts, and each lamp will have its own rating usually printed on the side. If customers have multiple bulbs on the same circuit, they need to add them together to work out the total load. Too little load means that the bulbs may not turn on or off properly. Too much load means that customers could damage or destroy the light fitting, so it is important to get this right.