AHJ Grounding Electrode Requirement

[jxofaltrds]

Why would it required to be bonded a second time if they are not isolated?

Bob we have been there. I say isolated most of you say no. Others agree with me but are afraid to say so.

 

[Smart $]

... I say isolated most of you say no. ...

Could be isolated is the correct initial assessment. While electrically isolated directly from cold inlet to hot outlet at the water heater, you have to include the likelihood of electrical continuity through directly-connected faucets (e.g. bathtub/shower ones), or others with conductive supply tubes and metal mixing-valve bodies. Bonding hot to cold with a jumper is just an easily verifiable means to remove any doubt.

 

[iwire]

Could be isolated is the correct initial assessment.

I agree.

But the EC could walk the inspector to the areas of the piping the EC feels has already joined the systems.

Bonding hot to cold with a jumper is just an easily verifiable means to remove any doubt.

I agree and might well be how I choose to handle it.

 

[jwelectric]

Where in the NEC does it require that metal water pipes be made electrically continuous?

If this is not a requirement where does it say that each and every piece of metal water pipe is to be bonded?

If there is no requirement to do either then why does it need to be confirmed that the two be bonded to each other?

And finally the transformer that is supplying my house has the bare conductor of my service drop connected to the bottom conductor at the top of the pole. Is this transformer a SDS? Is it even covered by the definition of a SDS outlined in the NEC?

 

[Smart $]

I agree.

But the EC could walk the inspector to the areas of the piping the EC feels has already joined the systems.

I didn't comment on how to approach verification, so the "but" was a little out of line. :huh:

Aside from that, I agree.

 

[iwire]

I didn't comment on how to approach verification, so the "but" was a little out of line. :huh:

:?

If you were offended I am sorry. :huh:

 

[Strathead]

Bob we have been there. I say isolated most of you say no. Others agree with me but are afraid to say so.

Part of my point here, that hasn't been taken up yet is the requirement to size this to 250.66! Why? What makes the water piping any different than any other metal piping system as dealt with in 250.104? The only thing I can see is the possibility that the piping may be used for a Separately derived system ground at some point. This is not a good enough reason to spend that kind of money arbitrarily to me. I don't believe that it is well enforced either. For example, what if the service is upgraded? Has anyone here seen an inspection of the entire piping system to ensure that the bonding jumpers, as required, have been properly sized to 250.66 when service is upgraded? I haven't and I have done a few school upgrades for example. This is a section of the code that NEEDS to be seriously looked at in my opinion.

 

[Smart $]

Where in the NEC does it require that metal water pipes be made electrically continuous?

If this is not a requirement where does it say that each and every piece of metal water pipe is to be bonded?

If there is no requirement to do either then why does it need to be confirmed that the two be bonded to each other?

It's a culmination of several requirements and their respective interpretations... the outcome may be a stretch from intended... but its not like you can call up a CMP member and get a formal interpretation over the phone, now, can you?

The code doesn't say metal water pipes must be made continuous. It says metal piping systems (likely to be energized) must be bonded. In many cases, the EGC of the connected equipment likely to energize the piping system serves that purpose. However, in the case of electric water heaters, the hot outlet is electrically isolated from the heater's metal tank and outer covering. If electrically isolated everywhere else, the hot water piping constitutes a separate piping system.

And finally the transformer that is supplying my house has the bare conductor of my service drop connected to the bottom conductor at the top of the pole. Is this transformer a SDS? Is it even covered by the definition of a SDS outlined in the NEC?

I have no idea why a service transformer being an SDS or not is even at issue. Its a utility transformer and not subject to the NEC's definition of an SDS...!!!

 

[Strathead]

Where in the NEC does it require that metal water pipes be made electrically continuous?

If this is not a requirement where does it say that each and every piece of metal water pipe is to be bonded?

If there is no requirement to do either then why does it need to be confirmed that the two be bonded to each other?

And finally the transformer that is supplying my house has the bare conductor of my service drop connected to the bottom conductor at the top of the pole. Is this transformer a SDS? Is it even covered by the definition of a SDS outlined in the NEC?

250.104 (A) (1) uses the word "system(s)" this can easily and IMO rightly be interpreted to mean the entirety of the water piping, otherwise it would need to state a definition of how long the piping needs to be to not be considered a system or part of a system. This is absolutely not a clear dictate of the code, and my exact reason for bringing it up.

 

[iwire]

However, in the case of electric water heaters, the hot outlet is electrically isolated from the heater's metal tank and outer covering. If electrically isolated everywhere else, the hot water piping constitutes a separate piping system.

Seeing as splitting hairs is what we do here .........


Electrically isolated or not, is it a separate piping system when it is mechanically continuous with the cold in often more than one location?

To me a home with a city water supply for potable water and a well pump for gardening would be better example of separate systems.

 

[jwelectric]

Seeing as splitting hairs is what we do here .........


Electrically isolated or not, is it a separate piping system when it is mechanically continuous with the cold in often more than one location?

To me a home with a city water supply for potable water and a well pump for gardening would be better example of separate systems.

I agree with this example. In my home I have two water systems, potable water the other waste water. The waste water is non-metallic and needs no bonding.

I have posted on this forum many times the comments of the CMP when it concerns metal water pipes and they say if it is not 100% then 250.104(B) applies. If the potable water is not electrically continuous from any point on that system to any other point on that system then it is not 100% metal water piping system.

In your example you have two water systems, potable water and gray water. Each would require bonding.

There is no requirement for making a potable water system electrically continuous therefore there is no requirement to bond hot to cold. They are both the same potable water system.

 

[Smart $]

Seeing as splitting hairs is what we do here .........

:happyyes:

Electrically isolated or not, is it a separate piping system when it is mechanically continuous with the cold in often more than one location?

Yes. The Code says metal piping systems... which is analogous to electrically continuous. If hot and cold are electrically isolated, then it is because the mechanical tie-ins are not metal. Does this split that hair?

To me a home with a city water supply for potable water and a well pump for gardening would be better example of separate systems.

Granted, a better example... but () providing an easily distinguished example was not my intent.

 

[Smart $]

:?

In context, the opening "but" of your statement indicates the gist of your comment being an exception to mine... but I made no statement to which your comment would be an exception to. :blink:

If you were offended I am sorry. :huh:

Not offended in any way. Hoping you weren't either (I apologize if so). Rick just got me off on a tangent earlier with his comment about my admitting to not being up to speed (his sentiment, not mine).

 

[don_resqcapt19]

...And finally the transformer that is supplying my house has the bare conductor of my service drop connected to the bottom conductor at the top of the pole. Is this transformer a SDS? Is it even covered by the definition of a SDS outlined in the NEC?

The utility transformer is not covered by the definitions in the NEC, but is the utility set up really any different from a SDS transformer that is covered by the NEC? Even with a code complinat SDS transformer there is a connection between the grounded conductor on the primay system and the grounded conductor on the secondary system. This connection is via the code required primary EGC and secondary supply side bonding jumper. There is an electrical connection, but it is not directly between a "circuit" conductor from each system, so it is an SDS per the NEC.

 

[suemarkp]

Your statement is the same mistake I already pointed out to someone else. It doesn't matter how much resistance is across a path, if no current is flowing through that path, then both ends of the path must be at the same voltage. That is Ohm's Law.

Who says there is no current flowing through that path? I think you'll find everyone's buried metal water pipe has current flowing between the earth and that pipe as long as it is connected to the service neutral. More will flow as the house uses more unbalanced current and the neutral voltage drop increases (but even with the house using nothing, that pipe is still a parallel earth path for someone else's house).

You were saying that ground electrodes help stabilize voltages to earth. Implicit to that statement is there a voltage is being applied to the pipe (voltage relative to the earth). Ohms law says that if there is a potential difference, then current will flow.

 

[Rick Christopherson]

Who says there is no current flowing through that path? I think you'll find everyone's buried metal water pipe has current flowing between the earth and that pipe as long as it is connected to the service neutral. More will flow as the house uses more unbalanced current and the neutral voltage drop increases (but even with the house using nothing, that pipe is still a parallel earth path for someone else's house).

You were saying that ground electrodes help stabilize voltages to earth. Implicit to that statement is there a voltage is being applied to the pipe (voltage relative to the earth). Ohms law says that if there is a potential difference, then current will flow.

I wasn't suggesting that there couldn't or wouldn't be current. However, your original statement suggested that it was impossible for a grounding electrode to equalize voltage irrespective of whether current existed or not.

 

[jxofaltrds]

Who says there is no current flowing through that path? I think you'll find everyone's buried metal water pipe has current flowing between the earth and that pipe as long as it is connected to the service neutral. More will flow as the house uses more unbalanced current and the neutral voltage drop increases (but even with the house using nothing, that pipe is still a parallel earth path for someone else's house).

You were saying that ground electrodes help stabilize voltages to earth. Implicit to that statement is there a voltage is being applied to the pipe (voltage relative to the earth). Ohms law says that if there is a potential difference, then current will flow.

In older areas I can take my Guassmeter and locate the waterlines in the yard.

Don't do plumbing work any more but when I did I use to carry jumper cables in case I had to cut the water line IF the GEC was 'bonded' outside of the 5' rule. Talk to any oldtime plumber and they will tell you about getting shocked removing a hot water tank! Should we have a hot/cold bond? NO it's just a dumb idea! Must be why I got most of the AHJs here, central Ohio, to start doing it back in 2003! Do they have a humble smiley?

 

[PEDRO ESCOVILLA]

i would definitly find all the code sections i could to show "the powers that be" they are wrong. if that doesn't suffuce, request a written statement as to when this is to go into effect and why. then , it needs to go thru the approcal process as a code amendment

 

[jwelectric]

Yes. The Code says metal piping systems... which is analogous to electrically continuous.

For many years the NEC mandated that metal water pipes be made electrically continuous but then the members of the CMP said that the electrician could not follow the plumber around every day and install jumpers when a non-metallic repair was made on a metal water pipe. The CMP also knew that the plumber was not an electrician so mandating that they make any repair electrically continuous was not justified.

So now I have installed the bonding across the water heater and along comes a plumber and makes a repair who is charged with ensuring that the system stays electrically continuous?

It is nothing more than silly.

 

[jxofaltrds]

For many years the NEC mandated that metal water pipes be made electrically continuous but then the members of the CMP said that the electrician could not follow the plumber around every day and install jumpers when a non-metallic repair was made on a metal water pipe. The CMP also knew that the plumber was not an electrician so mandating that they make any repair electrically continuous was not justified.

So now I have installed the bonding across the water heater and along comes a plumber and makes a repair who is charged with ensuring that the system stays electrically continuous?

It is nothing more than silly.

Who? The AHJ. Permits are required, in Ohio, so the AHJ will verify proper repair. You are not allowed to cover ANY repair work unless it has been inspected.

What is silly is to say because XYZ I don't have to do something.

Why do we add a ground rod to a waterline electrode? Because the metal water line may be replaced. Why do we bond the hot/cold? Because the fixtures WILL be replaced and the water tank WILL be replaced. A hot/cold bond insures that the "piping" remains bonded.