Not knowing what your using, you should be
able to use most spark testers.
Not knowing what ignition your working on,
or the size of your battery, I would say that
just testing for spark shouldn’t produce any
heat in the wires unless you using a high
amperage battery with an under sized wire.
I would suspect you have a short which may
be from the points being closed all the time.
Need much more information than you have
provided.
Tubs
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.