I wonder whether stranded copper instead of solid copper would resolve
your issues. Perhaps also a heavier gauge of copper with sturdy
insulation (#14 THHN, e.g.) would do the trick.

wrote:
Greetings,

I have previously used small wire for doorbells, intercoms, security
systems, etc. and have experienced some degree of wire damage at
tenants' hands simply due to the physical strength of the wire. I
could switch to romex but I don't really want to pay for it and fear it
might confuse someone into combining a high and low voltage system.
Where can I get solid ~12 AWG insulated steel wire? I remember being
able to purchase a 1 mile spool of 12.5 AWG galvanized steel wire for
electrical fences for under $50. What I want probably weighs too much
to economically ship off the Internet. Where can I find it locally at
a reasonable price and if nowhere then perhaps if someone could refer
me to a cheap Internet sight?

Thank you for your time,
William

PS: Is there some reason why this is a bad idea?