On Wed, 30 Jan 2008 11:28:50 -0800 (PST), wrote:
K&T was designed for free air flow around conductors at all times.

Yup.

insulation prevents that and can cause overheating and ultimately a
fire

Well, K&T was designed not to get significantly hot during operation.
However if the fuses have been replaced with bigger units it might get
hot, and then as before, the insulation didn't cause the problem, but it
did lessen the margin for error.

since connections are soldered in walls, get solder hot enough
and it will fail

Not proper K&T solder connections. The solder is just on there to seal
the connection (so it won't corrode) and is not necessary for mechanical
strength (because it has none) or electrical conductivity (because lead
and tin are not that great of conductor). If you have ever tried to
take apart such a joint, you would know what I mean.

A well done joint will not even drip molten solder unless mechanically
disturbed while the solder is liquid, but no worry even if it does. For
a summary of K&T splicing, see this pdf:
http://www.markhellerelectric.com/wusplice.pdf I didn't create it, but
whoever wrote it did a good job.

sdb
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