Dry-chemical extinguishers are quite messy and the powder is quite difficult to clean up. It can also be corrosive to some metals if moisture is present. Moisture can combine with this powder and form cement-like slurry that is even more difficult to clean up once it dries. The powder is quite fine, comes out at a considerable velocity and floats on air. This later point can be used to advantage by using a short burst into the air to form a heat shield so you can advance and get a better shot. Unfortunately it means if you discharge a fire extinguisher the powder travels considerable distances. A small powder extinguisher was used on a minuscule trash fire in a kitchen. Surfaces over 100' away had to be cleaned.

I have started shifting away from the universal ABC rated extinguishers to AB rated foam extinguishers. It is easier to use, way easier to clean up, noncorrosive, more intuitive to apply effectively because it aims like a low-velocity hose, foam is more effective against class-A fires than powder because it cools the material, and it is at least, if not more, effective against oil based fires because it fills voids and forms a self-sealing blanket over the fuel. It can be used as a prophylactic on fuel spills. The foam is, reading the fine print, rated as safe around electrical gear as long as the voltage is 150v or less to ground. Normal household power is 120v to ground, even the 240v circuits are 120v to ground.

It may not be an appropriate solution for everyone but it made sense for me. Something to consider.