Ascertain the Continuity of Earth Grid and Lightning Grid

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pinku gupta Member Join Date: Oct 2011 Posts: 5	Ascertain the Continuity of Earth Grid and Lightning Grid 09/11/2014 11:56 PM
	dear all we have a cable riser from earth grid and another cable riser from dedicated earth rod FOR LIGHTNING PIT both are burried underground when we check the continuity with multimeter we found it to be continious but when we change the lead of meter we find resistance value on checking the same with meggar we find it to be dead short continious pls explain this phenomenon as we doubt that both grids HAS BEEN conECTED is there any other method to ascertain whether both the grids are connected or discontinious underground regards
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RAMConsult Guru Join Date: May 2007 Location: NYC metropolitan area. Posts: 3230 Good Answers: 444	#1 Re: ascertain the continuity of earth grid and lightning grid 09/12/2014 12:25 AM
	A dead short reading from the Megger is to be expected, after all it is used to check insulation integrity not continuity. More than likely you're using a digital multimeter, they're notoriously bad when there's any chance that some form of stray current/voltage is in/on the circuit your testing. Either get a low ohm continuity tester or an old analog meter for your test kit. __________________ “Tell me and I forget. Teach me and I remember. Involve me and I learn.” Ben Franklin.
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prashanthng Associate Join Date: Sep 2008 Posts: 39 Good Answers: 1	#2 Re: Ascertain the Continuity of Earth Grid and Lightning Grid 09/12/2014 2:18 PM
	Use of Meggar to measure continuity or resistance is a wrong application of right device. The word "meggar" has become common place and even non-electrical engineers use it very frequently. A meggar can measure only insulation resistance (healthiness of insulation). It has nothing to do with grid resistance. Use 3 electrode method or 4 electrode method. Refer IS-3043
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SHOCKHISCAN Guru Join Date: Nov 2007 Location: Eastern Arizona mountains on Route 666 about a mile from God's country Posts: 1676 Good Answers: 122	#3 Re: Ascertain the Continuity of Earth Grid and Lightning Grid 09/12/2014 3:59 PM
	You really should consider purchasing a ground grid test system that is capable of utilizing a time domain controller to identify grid conductor length, continuity, and condition. There are several available and an internet search on ground grid testingwill yield a wealth of information. __________________ They said; "Brain size?" I heard; "Train size?" so I said: "I'll take a small one, thank you."
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HiTekRedNek Guru Join Date: Oct 2006 Location: 44.56024"N 15.307971E Posts: 8277 Good Answers: 270	#4 Re: Ascertain the Continuity of Earth Grid and Lightning Grid 09/13/2014 4:48 AM
	Modern digital meters are designed to have a very high input impedance,and a very low sensing voltage when measuring resistance. The high input impedance also makes them susceptible to very minute voltages interfering with an ohm reading. What do you mean "change the lead on the meter?" Are you changing the range of the reading? What value resistance are you reading on the meter? Some meters can read a very low resistance,so check the range setting on the meter. __________________ "A man never stands so tall as when he stoops to help a child." "Never argue with a stupid person.They will drag you down to their level and beat you with experience" "To create an apple pie from scratch, first you must create a universe"
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