Ground Resistance Tester Calibration

What is Electrical Grounding?

Electrical grounding is an electrical pathway that allows an alternating path for the current to flow back to the ground if there is a fault in the wiring system. It provides a physical connection between the ground and the electrical equipment.

 

The electricity in any wiring system consists of movement of electrons flowing through the metal wires and they take the shortest path of least resistance to go through the ground. If there is some issue and the neutral wire and it has high resistance the grounding path will ensure that electrical system has a direct pathway to the ground. This will inhibit power surges and protect the electrical equipment from damage.

 

Electrical Grounding

In every electrical circuit, there is a live wire which provides  the power, a neutral wire which carries back the current to complete the circuit and a ground wire which provides an additional path for electrical current to return to the ground to complete the circuit in case the neutral wire breaks down. This avoids any danger to anyone if there is a short circuit. A ground wire is a copper wire is connected with a metal rod in the ground.

 

If the wiring systems use electrical cables that have metallic sheath, then this metal usually used as the ground conductor between the wall outlets and the service panel. However, if there is no metallic sheath then an extra wire is required to provide grounding. Electricity always takes the path of least resistance, therefore if the neutral wire is damaged the ground wire  provides a low resistance path to the ground. This alternate connection allows the earth to act as a path of least resistance and prevents an equipment or a person from becoming the low resistance path and thereby get an electrical shock.

 

Ground Resistance Testers

Ground resistance meters test the resistance of soil to the passage of electric current to determine the adequacy of the grounding of an electrical system by ensuring an adequately large path for fault currents, an indispensable component of a safe, properly functioning electrical system.

 

Design of a Ground Tester

The ground tester uses the dc generator, rotational current reverser, rectifier, and potential coil. The main parts of this tester are current reverser and rectifier, these two parts are mounted on the dc generator shaft. This tester consists of two pressures coils like p1 and p2 and two current coils like C1 and C2. These two coils are placed across the permanent magnet. Both the pressure and current coils have two terminals, the one end of both coils connected to a rectifier and other ends are connected to earth electrodes.

 

The potential coil is connected to the dc generator directly and it is placed between permanent magnets ‘N’ and ‘S’. The pointer coil position is fixed on the calibrated scale. The magnitude of the resistance is indicated by the pointer. The resistance of the earth is defined as the ratio of potential to earth electrode and current, or the ratio of voltage and current.

 

Importance of Electrical Grounding

 

Protects Against Electrical Overloads

You may experience power surges at times or you may be exposed to lightning during extreme weather conditions. These events may produce dangerously high electricity which can completely damage your electrical appliances. By grounding the electrical system, all the excess electricity will go into the earth instead of frying the appliances connected to the system. The appliances will be safe and protected from large electrical surges.

 

Stabilizes the Voltage Levels

When you ground the electrical system, it makes it easier for you to distribute the right amount of power at the right places. This ensures that the circuits are not overloaded at any point and get blown as a result of it. The earth can be considered as a common reference point for the voltage sources in any electrical system. This helps in providing stabilized voltage levels throughout the electric system.

 

Earth Conducts with Least Resistance

One of the main reasons why you should ground your electrical appliances is that the earth is a great conductor and it can conduct all the excess electricity with least resistance. When you ground the electrical system and connect it to the earth, it means that you are giving the excess electricity to go somewhere without resistance rather than going through you or your appliances.

 

Prevents Serious Damage and Death

When you do not ground the electrical system, you will put your appliances and even your life at high risk. When high electricity passes through any device, it will be fried and get damaged beyond repair. An excessive amount of electricity may even start a fire, putting your property and the life of your loved ones at risk.

 

Determining if Current is Grounded or Not

You can check if an electrical appliance is designed to be grounded or not. If the appliance is equipped with a three-wire cord and a three-pronged plug, then the third wire and prong will provide the ground link between the metal frame of the appliance and the grounding of the wiring system.

 

To check if the electrical system is grounded or not by checking your power outlets. If there are three prongs in the outlet, then your system should have three wires, one of which will be a grounding wire. To get assured if the current is getting grounded or not you can do the electrical grounding test as mentioned below.

 

Electrical Grounding Test

You can follow this 5-step checklist using a receptacle testing device with complete caution for electrical grounding test:

 

Step 1 – The first sign of proper electric grounding is your outlet. If it is a three-prong outlet with a U-shaped slot, then you can safely conclude that it is a grounding component.

Step 2 – Insert the red probe of your circuit tester into the smaller slot of the outlet. This outlet is the hot wire that supplies power to your appliances.

 

Step 3 – Insert the black probe into the bigger slot of the outlet which is the neutral slot. This will complete your circuit.

 

Step 4 – Check for the indicator light. It will light up if your outlet is grounded and if it does not light up, reverse the black and red probes. If the indicator does not show up in either the electrical grounding test, then the outlet is not grounded and is not safe for use.

 

Step 5 – Repeat all the 4 steps in all the outlets of your home to ensure each and every outlet is safely grounded. Most old properties have undergone a lot of work and renovation and so, not every outlet may have been redone.

 

Electric grounding test is very important to raise the electrical safety levels in your existing accommodation and ensures that all your electrical installations are safe and stay safe over their entire service life.

 

Ground Tester Calibration.

The Ground Meter will ordinarily remain calibrated. It is, however, important to check calibration regularly. This may be done at the factory or you may do it yourself. The Tester is factory set to “Fail High” at 10 Megohms and “Fail Low” at 750K ohms. The “Pass” LED is a default setting based on the “Fail” parameters.

 

When checking calibration, use resistors of these exact values unless you have adjusted the Tester to different parameters. However, since grounding is a safety issue you should get your grounding meters calibrated at a certified laboratory.

 

e2b calibration is an ISO 17025: 2017 accredited facility. . We are NIST Traceable Wide scope of ISO/IEC 17025 accreditation. We can calibrate your Ground Resistance Testers to the highest industry standards. Please Contact e2b calibration for more information about our on-site services.

 

THE TRUE COST OF POOR QUALITY CALIBRATION

Poor calibration services could be more than just an inconvenience.