Line loss, or the power drop in a wire, depends on the wire length, size or gauge of the wire, and the current running through the wire. Larger wire gauge sizes have less resistance and can transmit more power without large line losses. Losses in smaller gauge wire, like that being used for controllers, remain low if the amount of power transmitted is small, or if the length of the wire is not very long.
All electrical systems are based on a supply of power at a certain voltage and frequency. Line loss refers to reductions in voltage or current that can often be random, usually of relatively low amplitude, and always undesirable. Line loss is an abnormality in the power quality that is being delivered to a system.
If the voltage is too low, the amperage increases, which can result in electrical components melting down or causing the electrical device to malfunction or break down.
Electrical wires have resistance; the longer the wire, the greater the resistance. When electric current flows through the wire, the wire's resistance results in a voltage drop according to Ohm's law.
Ohm's law relates to the voltage difference between two points, the electric current flowing between them, and the resistance of the path of the current.
Mathematically, the law states that V (volts) = I (current) x R (resistance) -- Put simply, voltage equals current multiplied by the resistance.
To guard your controllers and hardware against line loss, ensure that your voltage is correct and use the proper gauge wire for the length of wire being run. In addition, it is recommended to utilize a UPS (with battery backup) as well as a surge protector to help guard against other such power annoyances.