Bonding Copper Stubs for Plastic Piping

[jwelectric]

This is the question that needs to be addressed. What is a metal water pipe system?

Personally I can see no difference between short pieces of metal pipe used to stub out a plumbing fixture and a hot and cold water line isolated by the water heater. When does the pipe become long enough to require a bonding jumper or when does a pipe become short enough that it no longer needs to be bonded?

At what point is this non founded requirement to bond these pipes together begin and what code section is used to determine these requirements?

 

[radiopet]

Comments from the 2005 Handbook :
In those cases where it cannot be reasonably concluded that the hot and cold water pipes are reliably bonded through mechanical connections, an electrical bonding jumper is required to ensure that this connection is made.

Some judgment must be exercised for each installation.

It is my belief and I could be wrong.....but that the system as a whole would describe the actual system itself...the supply lines and so on. Now the stub ups in my mind are part of the system but in their location and nature for the most part....alone to me would not make a system...

Most of the time when I see stub ups that are metal and the rest of the system is plastic....no actual bonding would take place anyway....if the stub ups are metal and the system is metal....the point is moot I guess.

I do see plastic piping systems in houses and then stub out to a faucet outside with copper....is that stub part of the system....yes but the system itself is not metal so I would not require or apply that stub to the bonding process.

I think that portion of the Judgement would have to apply to your question as well as the AHJ who is actually looking at the present situation and thats about all I can come up with for I guess the lack of a defined determination otherwise.

..personally when I run my bonding jumper..I hit the cold and hot pipe...for the cost of a clamp....I cover my bases and the more the bond the more the better......now THAT was corny...sorry

 

[mdshunk]

This is the question that needs to be addressed. What is a metal water pipe system?

While there may not be a clear answer to what is a "system", you can deduce many installation types that are not a metal water pipe system. (such as the metal stubs on PEX systems, for instance) That will leave very few installations left in that grey area. Bond these suspect systems, and don't sweat it.

 

[jwelectric]

Based solely on the 2005 cycle of the NEC I am trying to figure out just when this requirement to bond around anything such as a water heater is required.

In 250.53(D)(1) there is clear language that states that any part of a metal water pipe that is being used as the grounding path is to be made electrically continuous. In the exception is says that the bonding jumper installed to the supplemental electrode shall be permitted to be bonded to the interior metal water piping at any convenient point. Should the jumper installed to the supplemental electrode come off the hot water pipe I can see the requirement to bond around the water heater. If the supplemental electrode if connected to the metal water pipe at the same place as the grounding electrode conductor I can see no requirement in 250.53(D)(1) to bond around a water heater.

In 250.104(A) the only requirement is for the point of attachment to be accessible.

What I am seeking is clarification on when bonding the metal water pipe as outlined in 250.104(A) requires the metal water pipe to be electrically continuous. Where is this requirement to bond the hot and cold pipes together? At what point is the metal in the piping system called a metal piping system? On what section would an inspector stand when requiring a jumper across a water heater?
:-? :-? :-?

 

[mdshunk]

On what section would an inspector stand when requiring a jumper across a water heater?

I'll just take a stab at this easy one.

• If both the hot and cold pipework are metallic -and-
• The cold is bonded via the GEC attachment or other means -and-
• There is some disconnect in continuity between the hot and cold pipework by some means -then-
• a jumper from hot to cold should be added someplace

The water heater is often the most convenient location, but that jumper could rightfully be anywhere from hot to cold. There are probably many 'hot to cold' jumpers that are unnecessarily installed, as there is continuity from hot to cold by other means several other places in the system (washer valves, shower valves, hot water boilers with domestic hot water coils, water heaters without dielectric unions, kitchen faucets, etc.)

 

[jwelectric]

I don?t understand you answer Marc.

If the metal water pipe is being used a grounding electrode then it must comply with 250.53(D)(1). Here the only part of the metal water pipe that is required to be electrically continuous is the part that is in the path of earth, other electrodes and the grounded (neutral) at the service. There is no requirement that the complete metal water pipe system be electrically continuous.

(1) Continuity. Continuity of the grounding path or the bonding connection to interior piping shall not rely on water meters or filtering devices and similar equipment.

When we are only bonding the metal water pipe the requirements of 250.104(A) apply. I can find nothing in 250.104 that requires the metal water pipe to be electrically continuous. I only see that the point of attachment is required to be accessible.

(A) Metal Water Piping. The metal water piping system shall be bonded as required in (A)(1), (A)(2), or (A)(3) of this section. The bonding jumper(s) shall be installed in accordance with 250.64(A), (B), and (E). The points of attachment of the bonding jumper(s) shall be accessible.

(1) General. Metal water piping system(s) installed in or attached to a building or structure shall be bonded to the service equipment enclosure, the grounded conductor at the service, the grounding electrode conductor where of sufficient size, or to the one or more grounding electrodes used. The bonding jumper(s) shall be sized in accordance with Table 250.66 except as permitted in 250.104(A)(2) and (A)(3).

I am failing to see where either section requires the total metal water piping system to be electrically continuous.

 

[iwire]

I am failing to see where either section requires the total metal water piping system to be electrically continuous.

How about this?

A Metal water piping system is always electrically continuous.....it's metal.

If a metal water piping system is interrupted by something that is not conductive, that non conductive point is the end of that particular metal water piping system.

Beyond that non-conductive portion another metal water piping system may begin.

Both of those systems are required to be bonded.

IMO the real rub is what separates a 'stub' from a 'system'.

I will stick my neck out and say a system must supply more than one item and a stub only serves one item.

 

[JohnJ0906]

I think I understand what you are getting at Bob. If hot and cold water pipes are not connected metallicly, they are considered seperate systems, so each must be bonded.

 

[jwelectric]

I think I understand what you are getting at Bob. If hot and cold water pipes are not connected metallicly, they are considered seperate systems, so each must be bonded.

I can't see how they would be separate systems as they both carry the same water. They both are used for the same purpose and they are both run to the same place with a couple of exceptions.
I can see how calling those different systems would be one way to justify something that is not required.
I ask that if we are going to call these two different systems then why don?t we call the metal stubs a system. What makes one more dangerous than the other?

I have an electrical system in my home. I am able to use both 240 volts and 120 volts from this system. Does this mean that I have two electrical systems in my home? Each of these two voltages will supply more than one piece of equipment.

Do I see a proposal for next cycle?

 

[George Stolz]

Do I see a proposal for next cycle?

Well, we all assaulted 210.52 with vigor last cycle, we can make this our next 15-proposal section if you want to.

 

[iwire]

I can't see how they would be separate systems as they both carry the same water. They both are used for the same purpose and they are both run to the same place with a couple of exceptions.

There is no reason not to call them different systems.

I ask that if we are going to call these two different systems then why don?t we call the metal stubs a system. What makes one more dangerous than the other?

That has been covered already in this thread.

I have an electrical system in my home. I am able to use both 240 volts and 120 volts from this system. Does this mean that I have two electrical systems in my home? Each of these two voltages will supply more than one piece of equipment.

Apples and oranges.

As far as the proposal go for it, it will either change something or clear up the intent as written.

FWIW I have not seen a real world issue caused by the current wording.

 

[jwelectric]

There is no reason not to call them different systems.

There is no reason to call them different systems either.
When we start calling it two different systems then we must make note at what point that the stubs stop becoming a system.

As to comparing apples to oranges I know that they both have seeds. What is the seed that the though pattern that there are two different systems grew from?

If the hot water pipes pose a danger would not the stubs under a sink be as dangerous?

A plumber installs a copper stub through the floor with a 90 and short piece of pipe to strap with before changing over to nonmetallic pipe.
Now we have copper water pipe exposed to the underside of the house.
Would this stub be at the same potential as if it were a complete copper pipe to the water heater?
A house is built on a concrete pad and has copper stubs exposed under every sink. Would these copper stubs be at the same potential as a complete copper pipe to the water heater?

In ?my opinion? one is as dangerous as the other. By what magic does the stub become less dangerous as the complete hot water pipe back to the water heater?

What is the purpose of bonding as outlined in 250.104?

In 250.4(A)(4) we are told; Electrically conductive materials that are likely to become energized shall be connected together and to the electrical supply source in a manner that establishes an effective ground-fault current path.
And in 250.90; Bonding shall be provided where necessary to ensure electrical continuity and the capacity to conduct safely any fault current likely to be imposed.

In both of these sections we see the wording ?likely to? but the metal water pipe must be bonded with a conductor sized by 250.66.
Why?
What is likely to energize this water pipe with the same amount of current as the service?
The answer is out there somewhere, who can find it?
I am eagerly awaiting an explanation.

 

[mdshunk]

When we start calling it two different systems then we must make note at what point that the stubs stop becoming a system.

Mike, a couple of quick questions:

• Is this issue causing you some particular trouble in the field?
• Is there some hazard created, in your mind, with regard to the present wording?

 

[George Stolz]

In both of these sections we see the wording “likely to” but the metal water pipe must be bonded with a conductor sized by 250.66.
Why?
What is likely to energize this water pipe with the same amount of current as the service?
The answer is out there somewhere, who can find it?
I am eagerly awaiting an explanation.

Mike, I don't have an answer. There were quite a few proposals to bring metallic water systems in line with .104(B) this session, and the only defense the CMP offered for bonding was essentially, "because the code currently says so and you haven't provided substantiation to change that fact."

In fact, the more digging I do, the more holes I find for my line of reasoning. If intimate personnel contact with the water pipe were the reason for unquestioned bonding, then sprinkler pipes would not be included in that requirement. However, by Ryan's proposal 5-240, the panel has stated that sprinkler pipes are to be included in the requirements for 250.50 and 250.104(A).

2008 5-240 Panel Statement:

A metallic fire sprinkler piping system is metal water piping system that is covered by Section 250.104(A). Section 250.104(A) does not differentiate or exclude between the various types of metal water piping systems that might be present in a building or structure. Section 250.104(B) covers metal piping systems other than those metal water piping systems covered by 250.104(A).

I do not believe people touch sprinkler piping on a regular basis.

In fact, Proposal 5-236 confirms your read on this section:

2008 5-236 Panel Statement: The requirements of 250.104(A) apply to complete metallic water piping systems. Where there is no complete metallic water piping system, then the requirements of 250.104(B) would apply for those portions of isolated metal water piping system likely to become energized.

So, by this statement, I would say that they do not consider an unbonded hot water pipe to be a hazard.​

To be honest, I see no rhyme nor reason to their actions on this topic, and definutely see no substantiation for the Table 250.66-sizing of the bonding conductor. I'd also be interested to see if anyone sees a pattern here I'm missing.​

​

 

[jwelectric]

Mike, a couple of quick questions:

I will do my best to give a good answer

Is this issue causing you some particular trouble in the field?

It has been an issue that I addressed in the field. It is also one of the most asked questions I hear in the classroom when conducting an Inspectors Class.

Is there some hazard created, in your mind, with regard to the present wording?

In my mind it is very clear. Where I see the problem is someone trying to enforce something that they can?t explain.
This could become very expensive in an apartment building.

I don?t think that it would be too much to ask if I were turned down for not installing a jumper across a water heater for the inspector to give me the code section that is in violation.
All I am asking for here is what section requires this bonding jumper. I have heard a lot of opinion but have not seen anything concrete as yet.

Some have said it don?t cost but a few dollars to go ahead and install it. If I do 100 houses next year I will spend some where in the neighborhood of $2500 in labor and material for something that no one can show me in the code that is required.
Now my wife is going to be as mad as a wet setting hen because I spent all my money doing something just because I didn?t know any better than do and she won?t be getting those diamond ear rings she was wanting for Christmas next yeat.
Now if you are married I do not have to explain what problems this could cause so yes it could be a problem in the field.

I think that Panel 5 had a reason for taking the requirement for a metal water pipe to be electrically continuous out of the code.
If it was so important I believe that they would have made a point of leaving it in the code or to make sure the requirement was in place to make sure there was no confusion about the hot and cold water pipes.

When bonding the metal water pipe it is in case that the pipe becomes energized not for a path of current flow under normal operation.
The metal water pipe is not a grounding conductor and is not to open any overcurrent device.
The metal water pipe that is bonded as outlined in 250.104 is not to stabilize the system to earth in the event of lightning or other high voltage.
Now why should it be made electrically continuous?

Just what is the purpose of bonding a metal water pipe as outlined in 250.104 and why does the bonding jumper need to be sized according to the service conductors?
What is likely to energize these water pipes?
Through these questions we will find the answer to jump or not to jump. At this point I am not doing any jumping at all.