units = Volts (DC) or Volts RMS (AC). Sometimes referred to as Saturation Voltage. In any solid state control that switches a load, there will be some voltage dropped across the output. This voltage drop or saturation voltage will often vary with the amount of current going through the output section and the load. It should be specified with current conditions.
Loss of voltage (electrical pressure) caused by the resistance in wire and electrical devices. Proper wire sizing will minimize voltage drop, particularly over long distances. Voltage drop is determined by 4 factors: wire size, current (amps), voltage, and length of wire. It is determined by a consulting wire sizing chart or formula available in various reference tests. It is expressed as a percentage. Water analogy: Friction Loss in pipe.
This is the difference in current along a circuit caused by the resistance of the lights and the wire. When using low voltage wiring it can cause lights at the far end from the transformer to be noticeably dimmer than the ones nearer.
When using 12 volts, the cable needs to be matched to the load and distance, otherwise there may be less than 12 volts at the end of the cable run. This does not cause damage to the luminaire, but if the voltage drop is considerable, then the light produced will have a yellowing effect and may also be dim.
Voltage drop is the reduction in voltage in an electrical circuit between the source and utilitization device. Voltage drop, which is present in all electrical circuits powering any device, must be considered to varying degrees in circuit design. In electrical wiring national and local electrical codes may set guidelines for maximum voltage drop allowed in a circuit, to ensure reasonable efficiency of distribution and proper operation of electrical equipment.