Replies

1. 
   RobinBallew | Aug 17, 2004 03:58pm | #1

   Sounds funny. No reason to attach the grounding line to the natural gas line. Sure this is correct?

1. 
   e2canoe | Aug 17, 2004 08:04pm | #4

   I am sure about what he asked for.  It was the only thing he wrote up at the final electrical inspection.  I got a left over piece of grounding wire (I redid my panel) and clamped the gas pipe to cold water pipe where they came closest to each other.

   Inspector came back.  Said OK and signed off.

   The other post about the plastic gas mains makes the whole thing make sense I guess.

1. 
   RobinBallew | Aug 17, 2004 08:48pm | #6

   I guess I'm missing something. What is the purpos of grounding the to the gas line if you are also grounding to the water line? Don't you also have a grounding rod outside too? Does that make 3 places to ground?

1. 
   BillHartmann | Aug 17, 2004 08:54pm | #7

   Actually what he is doing is BONDING the gas line to the electrical grounding electrode system.

   It is against code to use the gas line as a grounding electrode.

   The water line might or might not used as part of the grounding electrode system.

   But if the water line is not part of the grounding electrode system and if it is metal then it also gets bonded to the grounding electrode system.

   The idea is that all metal in the house is at the same potential.

1. 
   RobinBallew | Aug 17, 2004 10:52pm | #10

   Very interesting. So to restate, we are bonding the metal to the grounded electrical system. I guess I see your point. Would all this bonding of the HVAC also reduce static shock?

2. 
   DanH | Aug 17, 2004 11:58pm | #11

   Not likely to significantly reduce static shock, since that's due mostly to the insulating properties of floor coverings. Won't make it any worse either, though.

3. 
   e2canoe | Aug 18, 2004 01:01am | #12

   Thanks.  Makes sense.  Same potential level.

   And I just pulled out the inspection report - you're right, he used the word "bonding".  Sorry for the confusion.

2. 
   CorvairDuVal | Aug 17, 2004 05:11pm | #2

   Here in Stafford County, VA the inspector requires us to ground the gas line (natural or propane) to the electric ground. They do allow this ground to be at the appliance (furnace), a bare 12 ga wire from a ground clamp on the gas pipe to the junction box for the furnace.

   Frank DuVal

3. 
   DanH | Aug 17, 2004 06:58pm | #3

   I think that common practice now is to make sure all major metal components of a building (including metal siding) are bonded together somehow. This just helps assure that an accidental contact between wiring and some metal component doesn't cause injury. It also slightly reduces (on average) the potential for lightning damage, though I doubt that this is a significant consideration.

   Re gas, many gas service lines now used are plastic, and there is apt to be a plastic fitting or gasket in the gas meter, so relying on grounding through the meter isn't a good idea.

   Also, while you're at it, put a grounding jumper around your water heater and (if it's inside the house) your water meter. Cheap insurance.

1. 
   e2canoe | Aug 17, 2004 08:07pm | #5

   Oh oh.  I guess I should I have grounded all the metal resillient channels I put in the ceiling and walls! ;)

1. 
   DANL | Aug 17, 2004 10:25pm | #8

   And what about grounding all those nails in your house? And the heating ducts? :-)

1. 
   DanH | Aug 17, 2004 10:33pm | #9

   The heating ducts should be grounded, since there is a fair chance that a loose wire might contact one. Normally this will occur where they contact the furnace, but there may be a vibration damper between that should be jumpered.

   Ceiling grids wouldn't be considered a "major" piece of metal, I suspect, but grounding them wouldn't be a dumb idea, given the possibility of a fault in a lighting fixture.

   This stuff only takes a few minutes to accomplish, uses very little material, adds significantly to occupant safety (compared, at least, to many other code items), and produces a more professional looking installation. So why not?

1. 
   DANL | Aug 18, 2004 03:05am | #13

   I was trying, apparently unsucessfully to be funny, but I learned something--didn't know about heating ducts (or ceiling tile grids). Thanks for the info.

4. 
   WayneL5 | Aug 18, 2004 03:22am | #14

   When I built my house in upstate New York, I and the gas company had a discussion about this.  He said in some jurisdictions it's required to bond the gas pipe to the building's electrical grounding system.  In other jurisdictions, it's forbidden.

   The people who favor bonding do so to reduce the chance of a potential difference, such as a static charge, jumping to the gas line where there may be a leak, or within an appliance, possibly causing ignition.  The people who oppose an electrical connection do so because such a connection can cause corrosion of the gas line in the soil outside the building, depending on soil conditions.

1. 
   DanH | Aug 18, 2004 05:09am | #15

   The possibility of causing corrosion would probably depend on the nature of the main grounding connection. In theory, copper water pipe or a copper ground rod would tend to cause corrosion of a galvanized gas pipe. A galvanized water pipe or a concrete grounding electrode probably wouldn't.

   But since the gas pipe is likely to be grounded through the furnace anyway, and, if not there, then through the furnace of the house next door, this doesn't make a lot of difference -- the bonding strap is just "insurance" to assure it's all grounded.

5. 
   davidmeiland | Aug 18, 2004 05:29am | #16

   I've always seen the piping bonded... hot, cold, and gas. Done with a #4 braided copper wire and the cable clamps that wrap around the pipe and bite into it. The #4 heads back to the panel to the grounding buss, and from there it's #4 out to a pair of ground rods at least 6 feet apart (or is it 8 feet...)

   In our case the buried gas pipe is poly so there's no corrosion issue, but that's an interesting point.