“ACM” is a plastic sheet with aluminum skins. It would be plain idiotic to cover your DC in that (and residences too, but I digress). You can see from picture

“ACM” is a plastic sheet with aluminum skins. It would be plain idiotic to cover your DC in that (and residences too, but I digress). You can see from pictures of the OVH fire aftermath that the outer plates have melted holes in them characteristic of metal.