Standards twist connectors are used to join two or more wires. Also known as wire nuts.
Gray - Max 2 x 16AWG, Min 1 x 20AWG + 1 22AWG
Blue - Max 3 x 16AWG, Min 2 x 22AWG
Orange - Max 3 x 16AWG + 1 x 18AWG, Min 3 x 22AWG
Yellow - Max 2 x 14AWG + 3 x 16 AWG, Min 1 x 14AWG + 1 x 18AWG
Red - 3 x 10AWG, Min 1 x 12AWG + 2 x 18AWG