How to check the zero line leakage with a multimeter
What is leakage?
We know that the circuit through which current flows is called a loop. If the current is lost in the circuit, it is leakage.
The main cause of line leakage is the aging or damage of the insulation layer, or the breakdown of the insulation layer by high current.
The symptom of leakage is usually that the leakage switch trips, but it can be closed and soon trips again, that is, it trips continuously and irregularly. Once the leakage current is too large, it will form a short circuit to ground and cannot be closed.
The main purpose of measuring leakage is to measure the insulation resistance of wires and equipment to ground. Ordinary multimeters may not provide accurate values due to low voltage. The first way to measure the insulation resistance of wires is to use a megohmmeter. The insulation resistance of electrical equipment is usually required to be no less than 0.5 megohms.
If you must use a multimeter to measure leakage, a clamp multimeter is the best choice and the most accurate. The premise is to replace the leakage protector with an air switch and measure the current with electricity.
A circuit requires at least two lines to form a loop, and the sum of the currents in the two lines of the loop is zero. Using this principle, we can clamp two wires of a clamp multimeter at the same time. If the current is 0, the circuit is normal. If the current reading is displayed, there is a leakage phenomenon in both wires.
This method can also determine the approximate range of the leakage point. If the distance of the line is relatively far and long, we can choose to start measuring from the middle, which can save half of the time. After determining whether it is a front-end or back-end leakage, we use the same method to divide the circuit into two and gradually narrow the inspection range until the leakage point is locked.
Distinguishing between neutral and live wires with a multimeter should be a common practice for electricians.
We just need to set the multimeter to the highest voltage level. Then test the voltage between the two wires separately. The two wires with a voltage of 380 volts are both live wires, the one with a voltage of 220 volts is live wire, and the other is ground or neutral wire.
If the colors of the wires are all the same, it is difficult to distinguish between the neutral wire and the ground wire.
The voltage between the neutral and ground wires to the live wire is 220 volts, and the voltage between the neutral and ground wires is 0 or very low.
