I have a Sigeli 150tc and it allows me to use my kanthal builds in tc mode but I can't find whether or not that is bad for my
device or why I was told not to use it with kanthal
Can anyone help
Only the iJoy Asolo does something akin to TC with Kanthal, and they rightly refer to it as "Taste Control" instead. it's an odd duck, not sure just what, or how, it's doing what it does.
Not full TC though.
At the other end... like your Sig, the IPV D2 will allow Kanthal in TC mode (it's unusual).
This is handy for low power/high resistance vapers as the D2 does not step down or "buck" below the battery's voltage in Power mode, but it does in TC mode. It's a workaround.
But it doesn't/can't hurt the mod. It just doesn't provide the temp limiting function you would have with a TC-able wire (Ni, Ti, SS etc.).
If you don't need to do it as a D2 like "workaround"... there's no reason to. And no benefit.