water heater

[LarryFine]

So, just how long does a continuous section of metallic pipe need to be to be considered a system?

 

[jwelectric]

No, not at all. That would not constitute a metal piping system, and wouldn't require bonding to those metal stubs.

Then how much pipe must be required before we have a piping system? Could the short pieces be argued as easily as the hot water pipe?

Actually, to me, there are two requirements. One is to bond the system, and the other is that the bonding be accessible. But I've got to agree that it would be nice to find something that takes the guesswork out of this.

This is the part that I am having a hard time dealing with. Where is the guess work found in this section? It is very clear to me, make it accessible and be done.

Yes, but you'll notice that 250.4(A)(4) is Bonding of Electrically Conductive Materials and Other Equipment. I'd say that the metal water piping system falls into this category. And 250.4 contains the General Requirements for Grounding and Bonding. These are then modified by the requirements found in 250.104.

Now I must ask you to address the part of that section that says ?Electrically conductive materials that are likely to become energized? and explain how it is going to become energized.
Also if we are going to bring 250.4 into this discussion and use it to insure that the water pipe is continuous would we not also have to conform to 250.8 also?
If so would we be required to install a jumper sized by 250.66 at each sweated joint in a copper water pipe?

This requirement to bond the water pipes for other than an electrode showed up somewhere between the 1968 and 1975 cycles (I don?t have the ?71). I have posted a link that will show both cycles below.
1968 (there is no 250-80 and this is the only mention of water pipes)
http://i3.photobucket.com/albums/y63/jwelectric/250.jpg
1975
http://i3.photobucket.com/albums/y63/jwelectric/250-801975.jpg
Notice that in the ?75 cycle the requirement to bond was based on 250-95 which was moved to 250.122 in the ?99 cycle. When this requirement to bond the metal water pipe was introduced to the code, only the water pipe that was likely to become energized was required to be bonded.

In the 1984 cycle the requirement to size the bonding jumper was moved to 250-94 which was moved to 250.66 in 99. Part ?B? was added for other metal pipes and these could be bonded based on 250-95 (250.122 today). Notice the line beside the new part. In none of these past cycles was there a requirement to bond around anything except meters and filters when being used as an electrode.
http://i3.photobucket.com/albums/y63/jwelectric/250-2.jpg
I have been told that the practice of bonding across the water heater started some years back and was based on the suggestion made in the code as to heating ducks and other metal pipes and snowballed through the years. Every PE in the field suggested that this take place and the uneducated lay person took them at their word and only a handful ever questioned the practice.
With today?s technology more and more people are questioning this practice and the code panel has responded as outlined in their statements.
They say the same thing that they have always said and that is to bond those parts that are likely to become energized.

I will be at the Southern Sectional in Ft. Worth in Oct. and I will ask questions myself. Maybe together we can get to the bottom of this once and for all.

 

[mvannevel]

Then how much pipe must be required before we have a piping system? Could the short pieces be argued as easily as the hot water pipe?

We don't know how much pipe constitutes a system because they don't define it. I say short stubs of pipe aren't a system, but long runs of hot water piping are. Other inspectors may (and probably do) see it differently. And our problems are only beginning with this lack of a definition.

This is the part that I am having a hard time dealing with. Where is the guess work found in this section? It is very clear to me, make it accessible and be done.

While it's very clear to you, that it only need be accessible, to others (me for example) it still hasn't been made clear. Make the connection to an isolated portion of the piping accessible? The section says piping system, and I take that to literally mean the entire system.

Now I must ask you to address the part of that section that says ?Electrically conductive materials that are likely to become energized? and explain how it is going to become energized.
Also if we are going to bring 250.4 into this discussion and use it to insure that the water pipe is continuous would we not also have to conform to 250.8 also?
If so would we be required to install a jumper sized by 250.66 at each sweated joint in a copper water pipe?

More confusion. Why do they talk about likely to become energized in one location, and omit it in another? To me, 250.104(A)(1) either modifies the requirement in 250.(A)(4) or they've left something out. Which do you think it is?

They say the same thing that they have always said and that is to bond those parts that are likely to become energized.

Well, not exactly. It used to say that, but it doesn't anymore.

We could go on and on with this, but the bottom line for me is what I stated earlier. Sloppy code writing. These people are just like us. They aren't infallible. They make mistakes. And, just like us, they don't like being corrected. But this is one that needs correcting. If nothing else, just for the sake of clarity.

For what it's worth, even Soares Book on Grounding makes mention of ensuring that the hot and cold piping are bonded together (just as Mike Holt does). And I still happen to think that if it's that important that we bond this piping when it's not being used as an electrode, then it's probably just as important that we bond all of it. If it's not important enough to bond all of it, then we serve no purpose by bonding only a portion of it. The Panel needs to make up their mind one way or another.

 

[jwelectric]

For what it's worth, even Soares Book on Grounding makes mention of ensuring that the hot and cold piping are bonded together (just as Mike Holt does). And I still happen to think that if it's that important that we bond this piping when it's not being used as an electrode, then it's probably just as important that we bond all of it. If it's not important enough to bond all of it, then we serve no purpose by bonding only a portion of it. The Panel needs to make up their mind one way or another.

Here is a link to what Soares has to say;
http://i3.photobucket.com/albums/y63/jwelectric/Soars.jpg
if all of these items are important enough for them to say they need to be bonded then should they be required to be bonded as they outline?
I think that the panel has made up its mind as they have said in the response to the proposals.