grounding water lines and gas lines

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Stevenfyeager

Senior Member
Location
United States, Indiana
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electrical contractor
Hi, when running grounds to water and gas lines in a house, if you have outside disconnects, you run wire from them and not from the inside house subpanels, correct? I have had inspectors have me do it either way.
Thank you
 
Question by Bob eludes saying details may change the answer, but basically all general "bonding" goes back to the main or system bonding jumper (or disconnect) location. Some gas and water line bonding can (or will) be done through connected utilization equipment EGC.
 
Smart $ said:
Question by Bob eludes saying details may change the answer, but basically all general "bonding" goes back to the main or system bonding jumper (or disconnect) location. Some gas and water line bonding can (or will) be done through connected utilization equipment EGC.
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I talked to an inspector today, he said to go from the disconnect to the water line like I thought. To my surprise, I have to run #2 Cu. Also, to my surprise, no wire is needed to the gas line. Thank you
 
Stevenfyeager said:
I talked to an inspector today, he said to go from the disconnect to the water line like I thought. To my surprise, I have to run #2 Cu. Also, to my surprise, no wire is needed to the gas line. Thank you
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That's likely because the waterline qualifies as a grounding electrode under 250.50/250.52, and the GEC is sized per 250.66.
 
Stevenfyeager said:
I talked to an inspector today, he said to go from the disconnect to the water line like I thought. To my surprise, I have to run #2 Cu. Also, to my surprise, no wire is needed to the gas line. Thank you
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What size service/service entrance conductors?
 
Stevenfyeager said:
Thank you, table 250.66, I see the #2 Cu. I am using parallel 4/0 AL entrance conductors. Does this mean I use #2 Cu for grounding electrode conductor to my two ground rods also? Residential 400 amp service.
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Ground rods only require a #6 Cu GEC or bonding jumper. Did you do the calculation to find the equivalent area of 2-#4/0 conductors and then go to T250.66?
 
Stevenfyeager said:
two parallel runs of 4/0 4/0 2/0 AL
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You need to go to chapter 9 table 8 (conductor properties).
There you will see that 4/0 has a cross sectional area of 211600 circular mils. Since you have two of them in parallel you have 2 x 211600 = 423200 circular mils of supply conductor to use when applying 250.66.

That puts you into the over 250 to 500 kcmil row in the chart which requires a 2 AWG copper or 1/0 AWG aluminum grounding electrode conductor.
 
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