Ive been hit by 110 and 220. Electric fences with and without weed cutters (weed cutters will throw a prolonged shock in an effort to "burn" through the offending weed), electrical sockets, light sockets, and cutting through live wires that were supposed to be off.
Ive also been hit by a tazer (my brother is a cop). The tazer is debilitating for a few minutes ... then you just get upset.
Heres how to build a cheap Co2 chamber. Initial cost is about $1 and then about $0.50 for everytime you need to kill.
Find an old "tupperware" type container around the house. Make sure it has a matching lid. Drill a bunch of 1/4" holes in the lid. (This container is to keep the prey away from the dry ice. Direct contact with dry ice can cause frostburn or cause limbs to break off).
Find a 4 or 5 gallon bucket that has a lid. (Make sure its been cleaned out).
Put about 2" of water in the "tupperware" container. Get a half pound of dry ice and break it into small pieces (I use a hammer). Pour the dry ice into the "tupperware" container with the water. It will immediately start sublimating (changing from solid to gas). Snap the lid on the "tupperware" container. Put the "tupperware" container with the lid into the 5 gallon bucket.
Place the lid to the 5 gallon bucket on LOOSELY (as dry ice is constantly sublimating if you make it airtight it can blow off the top). Start dropping the critters into the bucket. They will be unconscious in 10-15 seconds and will expire in under 2 minutes.
I by dry ice at my local grocery store. It is $0.62 per lb.
If anything is hard to understand please post back and ill gladly go into more detail.
Bryan