Alternating Current in Electronics: Wires and Connectors
When working with line voltage (the power that comes from a wall outlet) in your electronic circuits, you must always use wire that's designed specifically to handle line-voltage currents. Depending on your needs, you may choose to use solid or stranded wire. Stranded wire is usually easier to work with because it's more flexible.
When choosing wire, make sure you get the right gauge for the current your circuit will be carrying. For circuits that are designed to carry 15 A or less (which is the maximum current limit for devices plugged into most household electrical outlets), you can use 14-gauge wire. If the circuit will carry no more than 13 A, 16-gauge wire is sufficient. For less than 10 A, 18-gauge wire is sufficient.
Lamp wire, also known as zip cord, is the wire that lamp cords and indoor extension cords are made of. It's usually two-conductor, nongrounded 16- or 18-guage stranded wire in which the two conductors are joined in a way that lets you easily peel them apart.
Lamp wire is the easiest wire to use for short connections within your project. You can buy lamp wire in bulk at most hardware stores, or you can buy an inexpensive indoor extension cord at a discount dollar store and cut the ends off.
Make sure all connections you make with wires carrying line voltage are secure. The easiest way to connect the wires is to use wire nuts. To use wire nuts, strip off 3/8″ or so of insulation from the two wires to be connected and loosely twist the two ends together. Then, slip the wire nut over the twisted end and tighten the nut onto the connection by pushing down and twisting.
When the wire nut is as tight as you can get it, check to make sure that none of the stripped wire extends below the base of the wire nut. For good measure, you can wrap a short strip of black electrical tape around the connection.
Another way to make connections is to use a barrier strip. Barrier strips come in various sizes and shapes. The small one pictured can make four connections; the larger one can make eight.
To use a barrier strip, simply strip away a short length of insulation from the end of the wires you want to connect and secure them under the terminal screws. If you’re using stranded wire, make sure that all of the strands are held by the screw. Loose strands can cause short circuits.