Water Authority Conflicting with NEC

[infinity]

Sorry, not seeing the difference. Either way the pipe is connected to the service grounded conductor. The GEC is just shorter/more direct/possibly lower resistance.

Cheers, Wayne

The difference is that the neutral current cannot return on the isolated metal pipe to the neutral of the building next door connected to the same metal pipe.

 

[wwhitney]

The difference is that the neutral current cannot return on the isolated metal pipe to the neutral of the building next door connected to the same metal pipe.

Right, the details of the underground pipe outside the building determine the potential conductive interactions with other buildings/services. But the difference in what the NEC requires you to do inside the building is minimal.

I.e. if the water authority's concerns have merit, then they are alleviated simply by noting "the underground pipe has a significant resistance due to the joining method" and not by "we made a change in the building from a GEC connection to a bonding connection."

Cheers, Wayne

 

[Hv&Lv]

That document is so full of errors that it's an embarrassment to the Agency that produced it.

Agreed..
Still wondering why they stick to it..

 

[kwired]

EGC's would not carry any current under normal conditions. A GEC connected to the water pipe and then directly to the service neutral would allow neutral current to flow on the water piping system under normal conditions. That seems to be the reason for their objection to connecting the GEC to the pipe.

If there is no GEC, those EGC's ultimately tie into the grounded service conductor and electrically are connecting same places together as a GEC would, so any concern of currents passing through the piping and causing corrosion or electrolysis are invalid, same currents can potentially exist.

But also as already mentioned DC currents are what should be a concern for electrolysis and corrosion.

 

[Sparky2791]

So if its DI pipe with bell and spigot then its not electrically continuous, so typically there will be at least one bell and spigot joint to the street main

Here is a thought. Would the nut and the bolt head keep the pipe electrically connected since they are metal? Meaning the pipe is considered a GEC.

 

[petersonra]

The NEC requires that you use a metal water pipe that qualifies as an electrode. The only code compliant method is the make the water pipe not an electrode and then simply bond it.

what difference is there between using it as a GE and merely bonding it? electrically it is basically the same thing.

 

[Sparky2791]

what difference is there between using it as a GE and merely bonding it? electrically it is basically the same thing.

They want no connection to the pipe at all.

 

[wwhitney]

They want no connection to the pipe at all.

That's never going to fly with the NEC. It requires bonding the internal metal water piping system regardless. The best you could do is convince them their concerns are unfounded, either because AC or because the underground water pipe resistance is high.

As for your last question, is the picture you posted of a typical underground joint? I thought Tom's point is that the underground joints are of a different style with a higher resistance.

Cheers, Wayne

 

[tom baker]

Here is a thought. Would the nut and the bolt head keep the pipe electrically connected since they are metal? Meaning the pipe is considered a GEC.


View attachment 2563187

I don’t know the answer to that, but that’s a restrained joint, used to keep pipe from blowing apart due to pressure. Often a concrete thrust block is used instead of restrained joint. That may be the fitting used under the slab from the OP. Now the DI pipe on the left commonly would use a push in o ring connection, that is not electrically continuous. Restrained joints are not common due to expense and added labor

 

[Sparky2791]

That's never going to fly with the NEC. It requires bonding the internal metal water piping system regardless. The best you could do is convince them their concerns are unfounded, either because AC or because the underground water pipe resistance is high.

Well they indicate they are ok bonding the internal water piping but want the incoming water line electrically isolated from the internal piping

As for your last question, is the picture you posted of a typical underground joint? I thought Tom's point is that the underground joints are of a different style with a higher resistance

Yes I was thinking about that after I posted that. But I imagine the connection is still mechanically joined together. Ill have to look into that. The AHJ basically already told us he is going to call the water authority and tell them TOO BAD we are not going against what the NEC requires. Although if correct about the not electrically joined pipe below grade it would sill be OK to disconnect the GEC from the pipe because not a grounding electrode any longer. Ill let them 'fight' it out but now I am just curious moving forward on projects. Although the first thing the electrical inspector will ask if I do not show the connection to the incoming water pipe is, why is it not connected?

 

[roger]

The AHJ basically already told us he is going to call the water authority and tell them TOO BAD we are not going against what the NEC requires.

Imagine that, who would have thought?

 

[kwired]

They want no connection to the pipe at all.

to which I earlier mentioned a pump or other item with electrical connecting to pipe will have an EGC, and it is ultimately connected to electrical anyway. Maybe not to the same standards as might be required elsewhere but there is a connection.

Even if you didn't run a wire type EGC, but had metal raceways and/or attached both raceways and piping to metal structure, you still have a connection between the two items they think they want separted.