On Saturday, April 13, 2019 at 6:35:07 PM UTC-4, wrote:
What do you guys use for chassis wiring on old tube gear?

In the old days, when I needed to replace some bad wires in an old tube
radio, I just salvaged some from old tube tv sets. But dont have them
anymore. Looking on places like ebay, I see suitable sized wire, but
most is rated at 300v or usually less. MUCH LESS.

My local hardware stores have "Automotive wire" which is generally
thicker than I need, but also rated at lower voltages than what is in a
lot of tube gear.

Personally, I cant see that thick insulation failing at 500v or so, but
it is a concern.

Alpha and Belden still appear to manufacture 600V hookup wire. Newark and other industrial suppliers still sell it.

Automotive wire is not designed for high voltage work, but if you like fires, go ahead and use it. The 'thicker insulation' is to prevent abrasion, not to provide insulation for high voltages.