Doug Miller wrote:
I always thought the reason for not soldering was after-the-fact heat.
Depending on the lead/tin ratio of the solder, it can have different
melting points.

Well, yes, but the melting point of tin/lead solder is at *minimum* 361
degrees F
http://store.whittemoredurgin.com/7800solderq.html

If a soldered wire heats due to a heavy load, it may
be hot enough to break the solder joint if the solder used had a low
melting point. Just what I was taught.

If your wires get within a hundred degrees of melting the solder, you have far
bigger problems than the solder...

I've seen many times in older wiring where the insulation was charred
6-8 inches back from a joint. Must have been a good amount of heat to
do that. If not enough to melt solder, repeated heating/cooling would
probably affect the solder enough to form a cold joint.