A 240-volt electrical socket is a common feature of houses and homes. These outlets power such appliances like ovens and clothes dryers, and are double the voltage of the standard 120-volt outlet. Because of the high voltage, and possible electrical hazard, they need to be tested safely. Most voltage testers like multimeters and neon light voltage testers need to be plugged directly into the outlet to register the correct voltage. But a digital voltage pen works completely differently.
Pull the appliance plug from the 240-volt socket.
Insert a digital voltage pen in only one side of the electrical socket. Since only one side of the outlet needs to be tested, a closed and dangerous electrical connection has been avoided.
Read the voltage on the digital pen. Some pens will read voltage automatically, and some must have a button pushed to read voltage. Either way, once the pen has been inserted and the voltage read, you will have the correct information whether or not the outlet is supplying 240 volts.
There are some voltage pens that only need to touch the actual wire insulation which supply a 240-volt outlet. No insertion of any kind is required, and these are the safest voltage testers made.
Safety first. Although these voltage pens are very safe when used correctly, always be extra careful around high voltage testing using any type of voltage tester.