1, measuring pen difference method.

　　According to the normal use of the measuring pen, usually can not distinguish between the electrical enclosure of the charged belongs to the nature of the charged, because usually measuring pen to measure the nature of the electrical enclosure of the charged, whether it is a leakage or normal charged, its neon bulb will be flashing. In order for the measuring pen to determine the charged nature of the electrical enclosure, the method of adding a ground wire to the pen is optional. Special Note: Assuming that the neon tube of the measuring pen is broken, regardless of whether the electrical enclosure is energized or not, it will not emit light, and the use of it to measure the electricity will be negligent heterogeneity. Therefore, the measuring pen must be used before the use of a power line to verify that the function is normal before use, in order to ensure personal safety and the accuracy of the difference.

　　2. Test lamp difference method.

　　The metal shell of the appliance and the usual incandescent bulb one pole connection, the other pole of the bulb and the earth or power supply zero line connection: if the bulb is not bright, usually belongs to the normal power supply; if the bulb is the same as the brightness of the 220V communication power supply, the appliance is an internal insulation breakthrough; if the bulb is darker than the connection to the 220V communication power supply, the appliance is poorly insulated. The latter two kinds of power belong to the abnormal power of the appliance.

　　3. Multimeter difference method: multimeter resistance (R × 10K file) to measure the resistance between the electrical shell and the power supply leads: if the resistance value is zero, the electrical internal insulation has been broken; if the resistance value is less than 2MΩ, the electrical internal insulation leakage, the smaller the resistance value, the more serious the leakage; if the resistance value is infinitely large or greater than 2M, then the electrical appliances are normally charged.

　　4. megohmmeter difference method: 500V megohmmeter to measure the insulation resistance of the shell of the charged parts. If the resistance is zero, it indicates that the leakage is caused by electrical internal insulation breakdown; if the resistance is greater than 2M, it indicates that the shell charged by the induced voltage. If the resistance is less than 2MΩ, but not zero, it indicates that the charged is caused by the leakage of electrical internal insulation.