cinder blocks?

[macmikeman]

Good morning all,

I was looking at the recent post concerning fishing nm cable into voids in block walls and have a question concerninng cinder blocks. Are these the red colored bricks? And if so does anybody know why they are considered to be different than cement blocks for use with nm-b cable? Thank you in advance.

[tonyi]

A real old style cinder block is hard to find these days. If you do they'll be noticibly lighter weight than a concrete block. The aggregate was actual burnt cinders in mortar/concrete slurry.

[richwaskowitz]

Could be the red units you decribed are terracotta (clay) tile blocks. Do they have a glazed face? Regardless, all these types of blocks are fairly porous and should be treated the same, I would think.