As a top I get to spend a lot of time worrying about what happens when things go wrong. With enough play things will go wrong.
My rope instructor, Max, taught an entire class on what to do when things go wrong at a bondage convention in Portland. His constant safety evangelism means that people around Seattle have really thought about cutting people out of rope, nerve compression, fire, positional asphyxia, and other problems. In his class he teaches bondage tops to flag safety shears (also known as bondage shears or bandage shears). At play parties in Seattle people understand.
The same thing is not true everywhere. At Mid Atlantic Leather, I carried these red handled scissors in my back left pocket for the weekend. I had a lot of people ask me why I was carrying them. It was my first realization that this is not a universally understood symbol. (I decided to keep wearing them anyways.)
These are not the only safety equipment. The most important piece of safety equipment is calm. But I am going to focus on the things that are easy to photograph.
I devote the front two corners of my dungeon to safety equipment. I figure that the corners of the room are the only places that I will be able to find in a power outage.
One safety corner is devoted to cutting implements. I keep a set of bolt cutters and multiple sets of safety shears in this corner. The reason that there's more than one is so that I can grab one set for when I play elsewhere. I don't want to ever have a situation where these isn't at least one pair in the corner.
I have never used this particular set of bolt cutters. Sets of bolt cutters get dull pretty quickly, and I don't want to waste one of the few really good cuts that I will get from them.
Since I believe a power outage is a possibility, I keep a flashlight in the corner. I also keep a fire extinguisher.
The one almost fire that I had was overheating light bulbs melting plastic. The boy chained to the floor and ceiling was not amused, but not frightened. (the fact that this happened while a family member was asleep upstairs probably didn't help)