Pointer multimeter use precautions

① When using a multimeter, you should develop a good habit of checking the position of the multimeter before each measurement. If you develop this habit, the chance of burning the meter will be greatly reduced.

② The range should be selected so that the pointer indicates near two-thirds of the full scale, and the reading is more accurate. If the magnitude of the measured voltage and current is unknown, a large range should be selected, and then the range should be readjusted according to the magnitude of the reading to make the reading accurate.

③ When measuring resistance, you must re-adjust the zero position after changing the range to ensure accurate readings. If the zero position cannot be adjusted, it means that the battery voltage in the meter is insufficient and the battery should be replaced.

④ When measuring resistance online, the power supply should be cut off for operation. Also, pay attention to whether there are other components forming a parallel circuit with the measured resistance. If necessary, weld one end of the resistance from the circuit before measuring. For circuits with electrolytic capacitors, the capacitors should be fully discharged before measurement.

⑤ When using a multimeter, develop the habit of not touching the metal part of the test lead to prevent electric shock accidents. At the same time, when measuring resistance, if you touch the metal part of the test lead, it will affect the reading.

⑥ When measuring DC voltage, connect the red pen to "+" and the black pen to "-" to prevent the reverse polarity from causing the needle to deflect in the opposite direction and damage the needle. If you don't know the positive and negative polarity, you can first turn to the large range, quickly touch the measured point with the test pen, and observe the direction of the pointer swing to determine the correct polarity. In particular, do not use the mA range or resistance range to measure voltage, otherwise the instrument will burn out.

⑦ When measuring current, never connect the two test leads across the power supply to avoid burning the meter head. Generally, a multimeter can only measure direct current, not alternating current.

⑧ After using the meter, the range switch should be placed at the highest voltage position. For multimeters with short circuit or disconnect positions, it should be placed in the corresponding position to prevent others from damaging the instrument when using it without paying attention.

So in daily work, many people have some wrong methods when using multimeters. Let’s take stock of them below. Have you done this too?

1. Replace the original multimeter fuse with a cheap fuse. If your digital multimeter (DMM) meets the electrical safety standards marked on it, then the fuse should be a special safety fuse that can be quickly disconnected before a serious overload occurs to ensure the safety of the instrument and personnel. When you need to replace the fuse of a digital multimeter, be sure to use a fuse that complies with safety regulations and is allowed to be used.

2. Use a piece of wire or metal sheet to replace the multimeter fuse. This seems to be a quick solution when there is no extra fuse on hand, but such a fuse may cause serious safety problems.

3. Using the wrong tool for the job. It is important to use the right DMM for the job. First, make sure the DMM (or other test tool) has the correct CAT (electrical safety) rating for each test you are performing, even if you have to switch between DMMs throughout the day. Second, make sure the DMM's maximum continuous operating voltage meets the actual test needs.

4. When using a multimeter to measure live circuits, disconnect the circuits as much as possible. If you must measure live circuits, be sure to use the correct insulating tools, wear ear protection, safety glasses, arc protection masks and insulating gloves, take off your watch or other jewelry, stand on an insulating mat, and wear flame-retardant work clothes (not ordinary work clothes).

5. Ignore the test leads. Test leads are an important aspect of digital multimeter safety. Make sure the test leads also have the appropriate CAT electrical safety rating for the job; and use test leads with double insulation (silicone material), guarded input connectors, finger guards, and non-slip surfaces.

6. Perform the test with both hands at the same time. Never do this! When measuring live circuits, remember a trick: put one hand in your pocket. This makes it difficult to form a closed loop through the chest and heart. Hang or put the multimeter down as much as possible, and avoid holding the multimeter in your hands, which will minimize the risk of exposure to transient voltages. Of course, in more dangerous measurements, additional measures should be taken to reduce hazards and arc flash risks. These additional measures include using protective equipment (such as protective gloves, protective clothing and goggles) specified in the National Electrical Code to provide arc protection.