Bonding both hot and hold supply pipes

I almost never see the hot and cold pipes bonded together at the water heater. I often see one or the other but it seems to me there ought to be a jumper between the two. Is this an AHJ issue?

No it is a requirement:

**See 250.104(B) Other Metal Piping **

Well I virtually never see a jumper to the hot water piping and almost never see the hot pipe bonded. Do you see it bonded correctly at the hot water heater most of the time? Anybody? Anywhere?

Predominantly bonded @ the water heater correctly.

**JOE, **
was this just added/changed for the 2005 NEC?

**KENTON, **
I would say that 80+% of the homes (with metal pipes) I inspect do NOT have jumpers!

This was bonding from cold water supply clamp for WH flues, chimneys, gas piping, and the jumper for H/C water supplies at the twin WHs at a new build in Frisco, TX this year. This is the only one I’ve seen done this way so far. The WHs did have dielectric unions.

I just finished discussing this with inspectors at the local building department who told me that it’s a matter of interpretation. They require the cold water pipes to be bonded, preferably to the grounding bus bar in the main panel or to a grounding electrode rather than the water pipes because plastic main water lines are sometimes used underground here. They recommend bonding the hot water pipes but they don’t call it a defect if they don’t see it.

Are the water pipes bonded as well?
I can’t tell from your picture. I only see the flues bonded to ground.
Is there any chance this is for lightning?
I have never seen this has anyone else?

Hypothetical questions about previous post.

With this flue bonding set up could the roof exposed flues become “lightning rods” and electrocute someone showering, let’s say standing in a metal tub, touching the plumbing control knobs?

Or would the strike always go back to ground?

Lightning strike or home current getting onto the pipes accidently. That was my concern.

As posted this WAS BONDED clamped at cold supply entry to this house.
I can’t locate the H-C jumpers photos right now but I am seeing H-C jumpers more often on new builds. Not all but they are out there.

Please reply to post #9

The bonding of those vents does nothing and is not required. The draft hoods do not make a good enough connection to even bond the tanks.

I see no hazard with this setup, but I see no benefit either.

Here is a good read for Grounding -v- Bonding (Sorry its not one link, it was a series of articles last year)

Checking earlier editions will show the same words around the Section 250-80 area, and the following has been in the NEC for many years:

[FONT=Arial Black]FPN: Bonding all piping and metal air ducts within the premises will provide additional safety.

I spent about 20 minutes talking with the county building inspectors, they were pretty relaxed and they’d been discussing it between themselves for a few minutes before they finally called me in.

I told them I was concerned about safety and liability and they just kind of rolled their eyes and in the ensuing discussion it was plain that so were they but that grounding and bonding (they made it plain) were one of the most difficult issues to nail down, Things keep changing and are different in different jurisdictions.

Around here, I think the main issue is that you’re recommendations must be written to keep people safe and your knowledge must be on a par with local practices generally accepted by local building officials.

No, it is not a requirement, Joe. Not nationwide.l Why did you say it was?

See the NEC Manual of Style for use of terms that are used when identifying various Articles and Sections in the NEC.

When adopted by any Jurisdiction the NEC includes instructions on enforcement procedures in 90.4 (often not clearly understood by some) and see Section 90.5 where “SHALL” is used in any rules in the NEC it is a requirement and is a mandatory term, and unless the local or State modified the NEC it is the law.

If you need further clarification on the question of adoption or interpretation of the rule in question question call the NFPA or IAEI directly and ask for an Official Interpretation.

• 250.104(D): Relocated requirements for bonding water piping and structural metal to separately derived systems from 250.104(A)(4) of 2002 Code.

250.104 Bonding of Piping Systems and Exposed Structural Steel

(B) Other Metal Piping Where installed in or attached to a building or structure, metal piping system(s), including gas piping, that is likely to become energized 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 250.122, using the rating of the circuit that is likely to energize the piping system(s). The equipment grounding conductor for the circuit that is likely to energize the piping shall be permitted to serve as the bonding means. The points of attachment of the bonding jumper(s) shall be accessible.

FPN: Bonding all piping and metal air ducts within the premises will provide additional safety."


“Unlike the metal piping systems covered in 250.104(A), this requirement applies only to metal piping systems that are likely to become energized. What this means is that where metal piping systems and electrical circuits interface through mechanical and electrical connections within equipment, a failure of electrical insulation can result in the connected piping system(s) becoming energized. Gas appliances are a common example of metal gas piping and electrical circuits being connected to a common piece of equipment, and in this case the 250.104(B) requirements apply. The required bonding of these other piping systems can occur at the same locations specified in 250.104(A), or an additional provision within this paragraph permits the equipment grounding conductor of the circuit that is likely to energize the piping as the means for bonding the piping. Typically, the use of an additional bonding jumper is not necessary to comply with this requirement because the equipment grounding connection to the non–current-carrying metal parts of the appliance also provides a bonding connection to the metal piping attached to the appliance. This is a bonding requirement, and the other piping is not being used as an electrode. Therefore, this requirement does not conflict with 250.52(B)(1), which prohibits the use of metal underground gas piping as a grounding electrode for electrical services or other sources of supply.”

I stand by my comments! :mrgreen:


Check your local code as it is written. I think you will find that bonding of the metallic water piping is required, even in your area. Whether or not this requirement is enforced, is an entirely separate issue.

This is not a defect, but it should be called out, correct? What type of wording should be used?

Any piping that can likely become energized is already 'bonded/grounded" by the circuit that can energize it. Example, 30a circuit to the water heater bonds it also. 120v cicuit to gas stove, has a ground too.


PS I have pipe clamps and 4awg for dedicated bonds in my house. hot 2 cold 2 gas 2 etc