Nice, I hit mine with a temperature gun while charging the car, pulling around 60 amps a while back. Slightly warmer than ambient, this was of concern to me. To that end I also mounted the DIN rail in a fully covered 12x12 steel box for the primary feed relay, and the 50A feed out to my EV pedestal (Feed wire to the pedestal is actually #4).
Also interesting as the higher amp units I have are switch left, controls right. The one I have that failed (mechanically not catastrophically) is like the one above, controls left, switch right.
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So I went back out just to verify a little bit ago... Fuzzy red dot on case is a reflection from the white side board @89.4
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Upper inputs are from the panel on the left. Lower inputs (top) are from the main panel, load wires are underneath. Load was around 8KW, HVAC && HWH running. Highest reading in the box right here at this spot 89.9 about 0.5F differential. Left relay feeds the EV pedestal, and yes I know you are not supposed to band red wire, at the time it was all I had. Right relay is the 100A primary to the panel on the left. I'll take another when the car is charging: I'll run some hot water, when the AC kicks on, but I did this before and didn't see much of anything that was of concern. BTW it's a good idea to hit the breakers in your panel from time to time. I had a brand new SquareD 50A breaker going to the HVAC that was heating up and tripping. Connections were all tight.
I will say that the connections on these things are difficult. You will note the lugs i installed on the top wires, this was to reduce stress on the box. I twisted and fought the crimp connectors on the lower panel feed, to minimize stress from the wire, it can distort the case, and pop it off the DIN rail.
Temperature checks are something I've gotten into a habit of doing since I started messing with panels and UPS's in my computer rooms. Just hit the gun on your twist-loc boxes, breakers and tie points around your ups. Caught more than one failure before it happened. Nailed a bad clothes dryer outlet right here in my house that had a weak contact as well. Doesn't take long.