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I recently noticed that I have ground wires attached to metal water pipes in my home, as shown in the following image.

The area marked A is where the water service enters the home with that blue handled valve being the main shut off.

The area marked B shows two exposed wires (assumed grounds) that are secured to the pipe which is the water heater's outgoing pipe.

Am I incorrect in thinking that the grounds should be secured to the other pipe, the one that brings water service into the home?

enter image description here

ctorx
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  • Do you have a ground rod(s) installed outside the foundation? – mmathis Aug 24 '18 at 20:13
  • Is the hot water pipe not the supply under ground as it exits? If it is in contact with earth for 10' it would have met code when installed. Normally the supply is bonded and the meters and valves were jumpered with copper wire, if this was an early plastic pipe feed but galvanized in the home this may have been the reason it was bonded that way code only required 10' of pipe in contact with earth. – Ed Beal Aug 24 '18 at 23:18
  • I originally posted an answer but have deleted due to confusion (and downvotes). Basically, my opinion (debatable...) is that there appear to be non-metal parts in between "A" and "B" and that "A" would (or likely was at one time) a compliant grounding location but that "B" likely is not and that checking for a low resistance between "A" and "B" would show if that is the case. I'll leave the rest to the experts. – manassehkatz-Moving 2 Codidact Aug 24 '18 at 23:20

2 Answers2

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Grounding, bonding, water pipes, and your situation

The old-school way of grounding a house to the cold water pipe performed two functions, not just one:

  1. It grounded the house electrical system to protect it against induced lightning and static charges
  2. And it bonded the house plumbing to the electrical system to allow fuses to blow or breakers to trip if a wire faulted to the plumbing

Nowadays, Code requires us put in a dedicated electrode (ground rods or an Ufer for most folks) to deal with problem 1, and that's what you can do here -- running 6AWG copper from the main panel (optionally through a conduit) to a pair of ground rods spaced 8' apart and driven 8' into the ground will get you a serviceable grounding electrode in most areas.

You will still need to move the existing grounding/bonding wire from the hot pipe to the cold pipe and add a 6AWG jumper from the cold pipe to the hot pipe, though -- this will ensure that your piping is properly bonded to the electrical system so that you don't wind up with a shocking tub spout because the dishwasher shorted out.

ThreePhaseEel
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Code requires the water pipe to be bonded at the point or within 5' of entering the home. Having additional grounding may have been added for portions that have been replaced with plastic but not completely removed the metallic plumbing. I have seen this on both copper and galvanized pipe. I also know some that add grounding at water heaters but it is not required . for many years /decades water pipe was the only ground many homes had as long as the pipe was in contact with earth for 10' it was legal. Meters , valves had jumpers to main contunity. If this is your main ground it is probably fine but I have found several older homes that had the supply lines replaced with plastic and the home had no ground. Adding 2 ground rods and running a #6 copper to the main service panel would be all that is needed to bring it up to modern code. No update is required by code.

Ed Beal
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  • The catch here is we don't know if this is the ONLY grounding, in which case it sure doesn't look right, or if this is old (replaced with something better) or extra. – manassehkatz-Moving 2 Codidact Aug 24 '18 at 21:05
  • This looks fine to me as code that was in place for many years. No it is not current code but almost no home built 30 years ago would pass current code and no updates would be required. In fact as I posted in my answer all that would be needed to meet modern code is 2 ground rods and #6 copper to the main panel. – Ed Beal Aug 24 '18 at 21:10
  • If this is the only ground wire, connected at "B", does that really work if there are plastic parts in various connectors so that there isn't continuous metal path from "B" to "A" to earth? – manassehkatz-Moving 2 Codidact Aug 24 '18 at 21:15
  • This may very well NOT be the main ground as this home started out small and many additions over the years.

    If I wanted to go the route with two rods, what are the specifics on that. Can I run a #6 copper from the ground bus in the panel, through a conduit of some kind, 12 - 15 feet from the panel and attach to 2 grounds rods more or less right next to each other? How far do I need to pound them into the ground? 6'? 8'?

     – ctorx Aug 24 '18 at 22:54
  • Since that is on the secondary side of the water heater I don't think that was ever code unless there is 10' of pipe in contact with earth after that point , we don't know if this is in a basement but it is a split level so that could have met code requirements at the time 10' of pipe in concact with earth. Not that much different as today's 2ea 8' ground rods. The single water pipe was standard for many decades so I stand by my statement, just as knob and tube is still legal there is no requirement to upgrade, could it create a better ground system? Possibly but not always. – Ed Beal Aug 24 '18 at 22:59