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.

MTW is a good choice. Some other options include: TEW (often synonymous with MTW), but also THHN and THWN. Back in the day when I was involved in designing control panels for industrial process control, these were the defaults. You can google the meanings and differences. We used different wire types based on if the panels needed to be UL approved and environmental constraints, etc. For most tube gear, (unless it is going on a sea vehicle) these wire types should be OK. The standard for us was 600V insulation.

Beware of buying wire on ebay (and other places such as home depot, etc)...most of the wire is copper clad aluminum which, IMHO, should be avoided. Pain to solder, does not make a good crimp connection.
(given this group, I am sure someone will wanna go to the mat on this point....lol. To each their own)
John