Electrical Ground Testing Procedure

However there are key differences between these two tests.

Electrical ground testing procedure.

The 3 point test requires complete isolation from the power utility. The ground probes need to be inserted into the ground at specific distances away from the ground rod. An illustration from the us nbs 1918 procedure for electrical ground testing. Department of agriculture usda rea bulletin 1751f 802.

The furthest ground probe needs to be at a distance that is 10 times the length of the ground rod. Testing procedures have been also developed. On modern electrical systems rcd s and rcbo s are regularly fitted these devices react to electricity missing from the circuit or installation such as when a person is receiving an electric shock as the electricity passes through his body to the ground earth. The first is the 3 point or fall of potential method and the second is the induced frequency test or clamp on method.

Not just power isolation but also removal of any neutral or other such ground. For instance if the ground rod is 8 feet 2 4 m long the furthest probe should be 80 feet 24 m away. Four of the most common methods of ground resistance testing used by test technicians are discussed below. Ansi ieee std 81 1983 ieee guide for measuring earth resistivity ground impedance and earth surface potentials of a ground system.

Prior to about 15 years ago the basic methodology for ground testing remained fundamentally unchanged since it was originally devised in the early 20th century. In areas where driving ground rods may be impractical the two point method can be used. Beyer wally electrical protetion grounding fundamentals pdf 1994 u s. Ground continuity testing ground continuity testing is the same concept as ground bond testing.

Electrical circuits have a separate ground or earth circuit that provides an alternate low impedance path for electricity to safely reach the ground in case of accidental physical contact. The procedures for earth resistance testing are referenced in ieee standard no. 2 point dead earth method. Neta world techtips ground testing in difficult installations by jeffrey r.

Inadequate electrical grounding or wiring on the customer s premises or. The end user would use a test instrument and probes to first inject a current into the earth between a test electrode and a remote probe measure the voltage drop caused by the soil to a designated point and then use ohm s law to. There are two 2 methods for testing an electrical grounding system. Standards procedures for testing the electrical ground system.

Download paper c the four potential method wenner method this technique helps overcome some of the problems associated with the requirement for knowing the electrical centre of the earthing systems being tested. Similar concept to the ground bond testing. Insert 2 ground probes into the ground.