To date, the measurement of ground resistance must be performed in order to make sure that it fully complies with all the requirements of the PUE, as well as PTEEP. All measurements that will be carried out in an electrical installation with a solidly grounded neutral (voltage below 1000 volts) must necessarily comply with the following standards.

The value that you get after taking measurements should not exceed 8, 4 and 2 ohms at a voltage of 220, 380 and 660 volts. If an isolated neutral is used in electrical installations, then the resistance of the ground loop will comply with clause 1.7.104 of the PUE and it will be calculated according to the formula Rz * Iz< 50 В. В этой статье мы рассмотрим основные методики замеров контура, а также приборы, которые необходимо для этого использовать.

Overview of Methods

To carry out a variety of measuring work, you may need to artificially assemble an electrical circuit where the current will flow through the tested ground electrode, as well as the current electrode. Also, a potential electrode will be used in such a circuit. Its main purpose will be to measure the voltage drop during the flow of electric current through the ground electrode. The potential electrode must be placed equally far from the current electrode and the tested ground electrode, in the zone where the zero potential will be located.

To measure resistance using the ammeter-voltmeter method, you will need to use Ohm's law. In most cases, this method will need to be used for a private house. You can also use a welding transformer to obtain the required measuring current. You can also use other transformers where the secondary is not connected to the primary.

Use of special devices

Even if you have a functional multimeter at home, in this case you must remember that it is not suitable for measuring the resistance of the ground loop. To measure the resistance of the ground loop with your own hands, you will need to use the following analogues:

• MC-08.
• M-416.
• ISZ-2016.
• F4103-M1.

Now let's look at how to measure the resistance with the M-416 device. Before using the device, make sure that it has power. You will need to place the finished device on a flat horizontal surface. Now you need to calibrate this instrument. The device must be put in the “control” position and the red button must be held down, and the value must be switched to the “zero” mode. To carry out measurements, it is necessary to use a three-terminal circuit. The auxiliary rod must be driven at least half a meter into the ground. All wires, you need to connect according to the diagram below.

The switch, which is located on the device, will need to be moved to the “X1” position. After that, it will be possible to hold down the knob and turn the arrow until it is in the “zero” position. The result obtained, you need to multiply by the previously obtained multiplier. This will be your desired value. In the video below, you can see how to measure ground resistance with a device.

If necessary, you can also use modern devices that can greatly simplify all the work of taking measurements. For example, you can use MRU-MRU200, MRU120, MRU105 instruments to measure earth resistance.

Working with current clamps

Ground loop resistance can also be measured with a current clamp. Their advantage will be that there is no need to turn off the grounding device and use auxiliary electrodes. Thanks to this, you will have a wonderful opportunity to quickly conduct the measurement process. Now consider . An alternating current will flow through the grounding conductor under the influence of the primary winding of the transformer, which will be located in the measuring head of the clamp. To calculate the resistance value, it is necessary to divide the EMF value of the secondary winding by the current value measured by the clamps.

What should be the frequency of measurements?

It is necessary to carry out resistance measurements, as well as partial excavation of the soil, regularly. In most cases, you need to be guided by the schedule that is drawn up at the enterprise or that you have compiled yourself. Many people who live in a private home neglect protection, but this should not be done.

If you are planning to perform an inspection, then remember that it is best to perform such a task during the dry season. Thanks to this, you will have a wonderful opportunity to achieve accurate results. If the test is carried out in autumn or spring, then remember that due to wet ground, the current may spread and therefore the readings will be inaccurate.

In order for the earth resistance measurement to be carried out by specialists, you will need to contact the appropriate company. After the verification is completed, you will have the opportunity to receive a protocol that will contain all the necessary data on the conduct of such a verification. Many laboratories indicate in this document the place of work, the purpose of the ground electrode system, and the seasonal adjustment factor. Below you can see an example of such a protocol.

Below you can also see a video that will tell you how to measure the grounding resistance of an overhead line pole.

Now you know all the methods for measuring ground resistance at home. If you do not have certain skills, then in this case it is best to turn to real professionals.