A screwdriver is arguably the single most common tool used for electrical work. Standard screwdrivers work just fine in many cases, but they have one big drawback in this application: at least half of the tool is a bare metal shaft that's a very good conductor of electricity. If any bare metal of the tool contacts a live electrical current, the whole shaft become live. And if the shaft is touching a metal box or other part, or your finger, bad stuff can happen. That's why electricians use insulated screwdrivers for certain jobs, and it's not a bad idea for homeowners, too.
What Is an Insulated Screwdriver?
This is a specially designed screwdriver that has a tough, non-conductive plastic cover over the shaft and handles. Only the tip of an insulated screwdriver is exposed. The insulation protects the user from the possibility of touching live parts of a circuit and the grounded walls of the box or other equipment. By having the shaft of the screwdriver protectively coated, it is safe to hold the screwdriver here to balance the screwdriver. In addition to the personal safety benefit, insulated screwdrivers also can prevent damage to delicate electronic parts that might be destroyed by an electrical short.
More Than a Plastic Coating
Many standard screwdrivers have handles made of the non-conductive material, but this is not a reliable guarantee that the handle is properly insulated. Insulated screwdrivers are not only designed inside-out for electrical safety, but they also carry voltage ratings specifying the amount of electricity they can resist. A professional-grade insulated screwdriver typically is rated for 1,000 volts. That's plenty for household electrical systems. Of course, these tools are made of steel, so the non-conductive coating must be intact to do its job.
Therefore, it's important to inspect your screwdrivers for damage before each use. Needless to say, this is not the screwdriver to reach for when you need a makeshift pry bar, floor scraper, hammer, etc. Save your cheap import tools for those ugly jobs.
Why Not Use Electrical Tape?
Wrapping a metal tool shaft with electrical tape may offer a small degree of safety, but it does not make an insulated tool. For one thing, the insulating material must be of a consistent thickness to provide real protection. Wrapping something with tape is anything but consistent.
Second, there's no way to know how much protection tape will give you. How much voltage your wrapping can handle is anybody's guess. And third, electrical tape does not have a strong bond and is easily damaged. If you're cranking on a tool and it slips and runs into a nice, sharp metal box edge, you could easily breach the homemade insulation and get right down to the bare metal.
The bottom line is, if you need an insulated tool, you need an insulated tool.