Advice 1: How to measure earthing resistance

In our everyday life is part of an increasing number of electrical appliances be it a microwave or a washing machine, a computer or a kettle, for the safe operation of which requires grounding. To make the ground easy, only needed an effective way to check its settings. Consider the functional variant.
How to measure earthing resistance
You will need
  • A device for measuring resistance M416, 2 auxiliary electrode, 2 wires with cross-section of 3.5 square millimeters with a length of 40 m Diameter electrode 16 mm, length 0.6 m.
Instruction
1
Place the auxiliary electrodes connect and check the earthing to the device M416 according to the shown scheme.
2
Hammer auxiliary electrodes into the ground to a depth of not less than 0.5 m blows vertically, not swinging them and loosening the ground around them. To increase the precision of the measurements (to reduce the resistance between the auxiliary electrodes and the ground) wet with salt water the ground around the auxiliary electrodes or increase of their number. Extension rods hammer at a distance of not less than 2 metres between them. The rods, forming a single auxiliary circuit, connect with each other electrically.
3
During measurement, place the device horizontally as close as possible to the measured circuit ground to reduce the length of the wire connecting the circuit ground to the device. This will reduce the measurement error introduced by this wire.
4
To measure resistance, do the following steps:1. Switch B1 is put in the position of ×1.
2. Press the button and rotate the handle "slidewire", ensuring the maximum approximation of the arrow to zero position.
3. The result of the measurement read from the scale of the slidewire, not forgetting to multiply it by a multiplier set by the handle B1.
If the measurement result is greater than 10 Ohms, set the switch of the multiplier of B1 in the next higher position and repeat measurements according to items 2 and 3.
Useful advice
This method is called the "Principle of reduction potential 3-point scheme" and is the best option to achieve acceptable measurement accuracy using relatively inexpensive equipment.

Advice 2: How to measure resistance with a multimeter

Sometimes a situation arises when you need to measure the resistance of the power cord (possible breakage) or to test the fuse, bulb, faulty heating element, and the like. With the help of multimeter these tasks are easy.
How to measure resistance with a multimeter
You will need
  • multimeter, test leads with probes (supplied with the multimeter).
Instruction
1
Insert the test lead black to the COM terminal of the multimeter, then plug the test lead red to the VΩmA socket. Turning the switch of the measuring range, turn the unit on. For measurements of small resistance, turn the switch in the Ω sector and put in position opposite the numeral 200 (measurement Range 0.1 – 200 Ohms). Short between the probes (to check the measuring circuit on the circuit), the display should show the numeric value in the range 0.3 – 0.7. This resistance measuring wire. Each time the multimeter check the resistance value of the measuring wires. When it increases to 0.8 Ohms, replace the test leads. With open-loop wires, the display should show the digit 1 in the leftmost register (very high resistance infinity).
2
To measure touch both contacts in the test circuit. If the chain or the consumer current is OK, the multimeter readings will change: it will show some resistance. In the case of a test for an open in the power cord, fuse or "continuity" of the wires, the resistance should be very low (in the range of 0.7 – 1.5 Ohm). But when checking the electrical consumers (lights, heating elements, winding network transformers) may rise to 150 – 200 Ohms. Moreover, this dependence can be traced – the more powerful the consumer is current, the less resistance.
3
If multimeter readings do not change, switch the measuring range of resistance, put the switch in front of 2000 numbers (0 – 2000 Ohms). And then if the display does not change, switch to the next range and measure again. Note: when the lock opposite numbers 2000K sensitivity of a multimeter is very high and if at the same time take his left and right hands for the contact probe, the instrument will show the resistance of the body that will distort the readings on the multimeter.
Note
All check the circuit and the loads must be disconnected!
Useful advice
Before each measurement, check the measuring circuit for a short. Do not forget to check the battery status: when the device and put the battery the display will show the battery symbol.
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