Thanks! Kinda simple in the end but did the trick nicely.Very clean....
...As I understand it, the temperature is not the temp of the actual heat sink or even relay. It's the temperature inside the box. So, for example, I was told to put a thermometer probe found in a kitchen inside the box. If it's under the ambient temp rating all is well.
Wiring up a box is one thing. Understanding it all is another. :rubeyes:
As to the temp; what paulcet said. The junction. Without any heatsink it would be the back of the relay.