Had to bore a breather hole for tankless water heater through 8” of solid concrete. Drilling horizontally about eye-level, this is a heavy boring tool, difficult to handle, so I built a wood fixture to help target and hold the weight. I think the bit can be used wet or dry, in my case dry cutting was my only option. Lot of DUST, so wear a breather mask and eye protection. I wore ear plugs too because it was an enclosed shed. The task took a week, about 20-25 hours of actual powering (slowly) through about an inch per day. If the drill angle is a tiny bit off, the whole thing BINDS UP and stalls the drill. I could stand and push the drill with my back leg braced agains the rear wall for maybe 10 minutes at a time before I succumbed to the fatigue. Rest for 5 - 10 minutes, and resume the attack. You’ll need patience and persistence because (in my case) it was literally a long, . . . hard, . . . grind.If your project is straight down into a concrete floor, your results will probably be more efficient.
Brian Thomsen 
