Just trying to help folks work through the thought process to use when they point their imager at an electrical component.
Shouldn’t you be off posting another “look at me” thread somewhere? :roll:
I think probably the simplest approach would be to compare the temperatures of the conductor sheathing closest to the connection and then farther away where it tapers off. The reason being is because I would know the conductor is under the same load along its entire length and the emissivity is most likely identical(Assuming heat hasn’t changed the surface of the sheathing near the connection). Even though the connection on the adjacent conductor is similar in materials, it is possible I might not be able to verify the load.
My answer is based on how you might approach it if you were definitely going to provide a Delta T. I would agree though, that a connection which tapers off is an automatic concern, so a Delta T isn’t really necessary. And the reason I agree with that is because Chuck and David taught me that about a year ago. 
No I really thought that was your Rodeo;-)
If you were going to do a Delta-T on it, that’s where I would shoot. However, given the condition of the insulation at both the connections, it’s clear that they have been significantly hotter than what we saw during the inspection and I would not be inclined to intentionally induce an increased load on those conductors to see just how hot it would get.
The IR in this case simply demonstrates that this is an immediate issue. I, frankly expected both phases to be hot.
In a similar situation do you ever intentionally put the conductors under a load because it may produce a useful image for your library?
I will put systems under load to find defects. I can’t recall ever having done nor would I ever expect to do so for the sake of collecting an image for my library.
If you do any real volume of thermography inspections, you will have more than an ample numbers of images to choose from you your library.