Hot electrical connection

In an infrared image, a hot electrical connection is a junction box, connector or joint that runs warmer than similar parts nearby. The heat comes from contact resistance: a bad or loose contact raises resistance and dissipates power at one spot. A junction box that is hotter than the other boxes can point to a cold solder joint or a loose connection inside it. Junction box interconnection failure and connector defects cause this pattern, and so do poor cell interconnections. Cables that loosen from thermal expansion can also arc at the connection point. Scan connectors while the circuit is carrying load. Take the images at high irradiance in steady, clear, low-wind conditions so that artefacts such as shading or dirt can be ruled out. Some faulty joints, such as an open bypass diode connection, heat up only when the module is shaded or during a night string reverse-bias test. A normal daytime scan can miss them. A hot connection can leave discolouration and burn marks around the junction box. It can also lead to arcing and fire, so act on it quickly.

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• sentence 1: support check: partial - Passages show hot junction boxes/hotspot Jbox in IR and that a box hotter than other boxes indicates a problem, but do not define a hot connection as a part running warmer than similar nearby parts including connectors/joints generally.
• sentence 5: support check: partial - Passages support IR under load, high irradiance (>600 W/m²), no clouds, low wind, and excluding shading/dirt, but only generally for modules and not scanning connectors specifically (connector evidence only says IR under load).
• sentence 7: support check: partial - Discolouration, burn marks, arcing and fire risk are stated, but the advice to act quickly is not explicitly stated, though u3 urges testing all modules due to high fire risk. -->