MC4 connector

In the past, this was accomplished by opening a small electrical box on the back of the panel and connecting user-supplied wires to screw terminals within.

Additionally, these sorts of connections were subject to problems caused by water leakage, electrical corrosion and mechanical stress on the wires.

A US-based and a Swiss company, Tyco Electronics and Multi-Contact (purchased by Staubli in 2002), responded by introducing new connectors to meet this requirement.

Later, the MC4 PV connector, launched in 2004, provided these positive locking mechanisms, leading to widespread market acceptance.

Among these was the fact that the system had two sets of cables and wires, which led to considerable annoyance in the field when equipment from different vendors could not be plugged together.

The socket has two plastic locking tabs that have to be pressed toward the central probe slightly to insert into holes in the front of the plug connector.

When the two are pushed together, the fingers slide down the holes until they reach a notch in the side of the plug connector, where they pop outward to lock the two together.

Staubli's (formerly Multi-Contact) MULTILAM Technology claims that constant spring pressure provides reliable low contact resistance.

An electric arc may form which can melt and seriously damage contact materials, resulting in high resistance and subsequent overheating.