Which gland size is correct to ensure IP rating is maintained? The Staübli Group in Germany manufactures the renowned MC4 connector. More often than not, it is the connector of choice of module manufacturers. For the installer, this means that to ensure safety (and compliance with AS5033) the exact same model of connector should be used at site when wiring in the strings.
However, in our field trails, we have found that often the gland will twist out, or cross thread. When this happens, it is not uncommon for the installer to back off the gland so it stays ‘square’. However this leaves the IP rating compromised. The consequence of moisture penetration in the connector are grave. Moisture can lead to corrosion, which in turn leads to high resistance, and heat; the heat leads to a still higher resistance and then what is known in the industry as a ‘runaway thermal reaction’. A failure of a connector has been known to lead to arcing and fire burning out an entire module and even melting portions of the aluminium framing.
So, what is the correct gland size to use?
Our tests have left us a little more sure but we are still conducting further trials to establish consistency and indeed whether or not we should even be using the MC4.