

The maximum rating is there because anything larger and the metal inside the wire nut will not be able to properly twist the big group of wires to cause a solid connection.

The minimum rating is there because any combination of wires smaller than 2 #14 AWG wires will simply fall out of the wire nut. Size of wire Nut – The most common RED wire nut by ideal can hold a MINIMUM of 2 #14 AWG wires and a MAXIMUM of 4 #12 AWG wires.In the worst case scenario it will cause a fire.

This can at the very least cause nuisance tripping of breakers. Under twisted wires will not form a solid connection and arc in the wire nut.
