Why Use Low Voltage for Outdoor Lighting?
Don’t let the fear of electricity affect your lighting aspirations. Low voltage can power lights but it cannot shock you. Understanding basic electricity is doable.
Passing a magnet over, say, a six inch piece of copper wire would (momentarily) force some copper electrons to one end of the wire. Like compressing a spring, potential energy is stored then released as electrons return. The force or pressure caused by the dislodged electrons is measured in VOLTS. So momentarily, a voltage appeared across across the two ends of the wire.
Voltage is to electricity what PSI (Pounds-per-Square-Inch) is to a tire where the more air pumped in, the harder it pushes against the inside wall trying to escape.
One indicator of PSI is the noise air makes while being released from, say, a tire through its valve. The noise is actually feedback to the presence of pressure. As air escapes, the pressure (PSI) goes down along with flow of air and indicated by the noise it makes.
Well, voltage is electromotive pressure . It’s measured between any two points in a circuit (like the two contacts on a battery) where electrons, not air, are trying to get from one post to the other. A light [filament], connected between the posts provides a path (like a tire valve). Feedback, in this case, to the existence of pressure (voltage) would be light. As electrons flow from one post to the other, the electromotive pressure, the voltage, would gradually wane and the light would grow dimmer.
With electrical pressure, anything that conducts electricity can serve as a path, like the human body. If the body touches both posts of a battery, electrons flow. The feedback, if the voltage were high enough, would be a shock! However, the current flow from 20 volts or less is not enough to be felt. 24 volts might produce a tingle depending on the moister of the skin.
The typical electrical outlet supplies about 120 volts. If the body were to come between 120 volts, a painful shock would result. Under certain conditions involving, say, water – 120 volts can even deliver a fatal shock.
So, 12 volt lighting is all about safety, not efficiency. The light from a 20-watt low voltage bulb is identical to a 120 volt counterpart. However, electrical energy is much more easily transported using higher voltage. That’s the reason we tolerate its danger.