Castable Refractory and Electricity

[Techtical]

Is castable refractory(mizzou) electically conductive? I ask this because i am wanting to make a muffle furnace and can only find alumina ceramic tubing in small diameters. Anything of reasonable size is crazy expensive. I was wondering if mizzou is basically the same composition and if so then i could cast a much larger tube for an electric muffle furnace, say 5 or 6 inches in diameter by 18 long.
I know mizzou is meant for high temps but is it strong enough and safe enough to wrap heating coils around to make an oven?

 

[Stacy E. Apelt - Bladesmith]

Once cured it is non-conductive.