Paul,
I have quite a bit of experience in using wirenuts, we use them all the time for performing "tap-offs", from Overhead Lines to Transformers and DropOut fuses.
Most of the wires we use for these purposes,
come pre-twisted, if you get my drift,ie: they are twisted up more than a standard stranded wire.
Wirenuts in this respect are the only thing, we can use to effect a decent connection,
especially, where High Voltage is concerned,
as with any loss at these voltages, can have very damaging effects. [Linked Image]