Grounding System in Class 1, Div 1 Room

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Anonymous Poster	Grounding System in Class 1, Div 1 Room 06/06/2008 12:23 PM
	At our plant we make products with methanol and ethanol. We have had an explosion and fire and the fire inspector has blamed the cause on a bad hose line that lost its ground. I have since found out that the grounding that we have had in place, obviously is not up to specs. I have read that we should have a resistance reading of 1 or less ohms. I have since installed a #6 wire to structural steel and water pipe and have looped the grounding cable around the mixing tanks and individualy grounded them I am getting a reading of 1, however when I attach the hose (that is wound with ss the reading goes back up to 3. I am in the process of using all ss lines thus helping the grounding issue. I will still have to use a hose for part of the process. So... is using a multimeter to test grounding ok or should I get a megger. Also what are acceptable readings. Thank you.
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bhankiii Guru Join Date: Sep 2006 Location: El Lago, Texas, USA Posts: 2639 Good Answers: 65	#1 Re: Grounding system in class 1 div 1 room 06/06/2008 4:20 PM
	I would use a four wire Ohm-meter. Make sure that you have calibrated out the resistance of your probes.
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bob c Guru Join Date: Jul 2007 Location: Fort Lauderdale Florida Posts: 5708 Good Answers: 123	#2 Re: Grounding System in Class 1, Div 1 Room 06/06/2008 9:21 PM
	Mobile fueling trucks at US airports are required to be equipped with bonding-grounding cables. Try checking with an airport refueler at your nearest airport. If you have trouble getting the requirements, reply to me on Monday, I can find them when I go back to work. Good luck. __________________ Bob
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garth Guru Join Date: Sep 2006 Location: NSW Australia Posts: 1101 Good Answers: 23	#3 Re: Grounding System in Class 1, Div 1 Room 06/07/2008 7:55 AM
	Using a multimeter for low ohm readings is not the best instrument. You should use an accurate constant current supply which can be adjusted up to say 10 amp wire this to the circuit that you wish to test and measure the voltage drop across it. This confirms good connections and the volt drop measured using a reasonable quality DDM will be quite accurate. I am not sure where you are measuring with regards to the SS hoses but SS has a high resistance relative to copper. __________________ Dont get on to the roundabout if you dont know how to get off
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dg1258 Associate Join Date: Mar 2008 Location: north east Posts: 29	#4 In reply to #3 Re: Grounding System in Class 1, Div 1 Room 06/07/2008 9:17 AM
	Don't over look any sealing compounds,if used in your piping systems
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bhankiii (1); bob c (1); dg1258 (1); garth (1)

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