The best way to describe this device is to say it has a circuit board inside it which is constantly measuring the flow of electrons within the circuit. When one side of the circuit gets out of balance from the other the circuit board detects a fault and trips shutting off the flow of electricity. Think of it as a river flowing underground which resurfaces a short distance away. If the river has always had the same flow and all of a sudden only half the volume emerges from the ground you would know there was a problem. The GFI works the same way. If even a little of the current strays into your body for instance, the GFI will detect it and trip potentially saving your life. We know that as little as 1 amp of electrical current can kill a person. The breaker in most cases will not trip until it reaches a load of 15 Amps. The GFI will trip at 5 milliamps or 5% of one amp.

A lot of electrical appliances such as hair dryers have been ruined by trying to run them on a razor plug. The problem is the razor plug has a transformer in it which reduces the electricity down to around 20 watts. Your hair dryer needs a much higher wattage as does most modern appliances. Due to the size of the transformers in these razor plugs the box needed to be fairly large. If you plan to remove the razor plug you need to decide how to fill the double wide box. Some people install two duplex receptacles in the box but this is awkward and overkill as you never need more than two receptacles to plug into in the bathroom. The best approach is to buy a replacement receptacle specifically designed for this purpose. Most hardware stores have a replacement kit available. Remember electricity is dangerous so if you are not confident and knowledgeable on the subject you should hire an electrician for your electrical needs.