1. Test method for lightning protection and grounding

Detect the grounding resistance of lightning rods, high-rise buildings and other facilities, and whether it can be smoothly led into the ground after lightning.

1. You first find the ground lead of the lightning protection grounding grid or the equipotential bonding box;

2. Use a grounding resistance tester to measure the grounding resistance;

(There are two 0.4M test piles to be inserted into the soil, one is 20 meters away from the test point, and the other is 40 meters away. Therefore, there must be soil within 42 meters of the test point. Use the FC-2G lightning protection grounding resistance tester to test the grounding. Resistance, if there are two test piles, insert the soil, one is 20 meters away from the test point and the other 40 meters, so there must be soil within 42 meters around the test point, or use FC-2G lightning protection grounding resistance tester, directly Stuck the ground wire test).

3. The smaller the grounding resistance value, the better. The specific qualified value must be specified in accordance with the design requirements when the design requires it, and it cannot be greater than 4 ohms when the design does not require it.

2. How to test the grounding resistance of lightning protection

1. Regulations on the wiring method when measuring the grounding resistance value

The E-terminal button on the instrument is connected to a 5m wire, the P-terminal button is connected to a 20m wire, and the C-terminal button is connected to a 40m wire. , C should maintain a straight line with a distance of 20m.

Wiring diagram when measuring grounding resistance greater than or equal to 1Q.

Connect the two E-end buttons on the meter together.

Connect the two E-terminal button wires on the meter to the grounding body to be tested to eliminate the additional error caused by the resistance of the connecting wire during the measurement.

2. Operation steps

All wiring at the instrument end should be correct.

The connection of the meter should be firmly in contact with the ground electrode E, the potential probe P and the current probe C.

After the meter is placed horizontally, adjust the mechanical zero position of the galvanometer to zero.

Set the "magnification switch" to the maximum magnification and gradually increase the cranking speed to 150r/min. When the pointer of the galvanometer deflects in a certain direction, rotate the dial to restore the pointer of the galvanometer to "0 point". At this time, the reading on the dial is multiplied by the magnification gear to obtain the measured resistance value.

If the dial reading is less than 1, the galvanometer pointer is still not balanced, you can set the magnification switch to a lower magnification level until it is fully balanced.

If you find that the pointer of the meter galvanometer is jittering, you can change the rotation speed of the crank to eliminate the jitter.

Three, lightning protection grounding test matters needing attention

1. It is forbidden to measure when there is lightning or the object under test is electrified.

2. The meter must be handled with care when carrying and using it to avoid severe vibration.