water heater

[George Stolz]

It is my belief that there is no requirement to bond around a water heater with a conductor sized by table 250.66 when bonding the water pipes as outlined in 250.104(A)(1).

I agree.

I am hoping to get some input into this to help me decide which side to pull for. Either

• bond the pipes based on Table 250.66 as outlined in .104(A)(1)
• bond as outlined in 104(B) using Table 250.122
• no bonding required at all.

I would say of the three options, the first looks easiest to enforce. The second and third would be easily shot down by 250.104(A).

 

[gndrod]

Hi George, I might have mislead you in mentioning a diverter valve which has a mixing valve in modern center controlled shower fixtures. Diverters are not found in lav or kitchen mixing center controls. Note that lav and kitchen faucets do not electrically connect the plumbing copper unless a metal supply hose or tube is used. When the diverter 'cross' is connected, it is either sweated or male adapter connected. Most plumbers use teflon (TFE or FEP) in sealing the threaded connection. Rarely is misapplication of over use of teflon tape create a dielectric union at the joints but it has happened to where AHJ's do disqualify a mixing/diverter valve continuity unless proven electrically sound. Even with the advent of cpvc and pex, occasionally the copper does get spec'd in custom homes and still exists in remods abundantly. So with this info hopefully a word of caution may help all electricians know a lot more than the plumbers do.

 

[gndrod]

jwelectric,
I can see the quandry of NEC bonding as a function of system or a function of EGC usage in determining metal water pipe electrode integrity relevant to water heater dielectric 'bond around' (not to be confused with EG bonding) safety. IMO the bond around of both gas and electric WH's can in effect be observed as a continuous metal electrode when referring to a lightning or transient bonding. The bond from H-C would be a continuation of an electrode path exclusive of EGC bonding for fault current safety. I believe the 250.66 is referenced with this intent in 250.104 and 250.68(B) sections for grounding specifically to continue to the system GEC in the same conductor sizing.

I know this is debatable but using 250.122 is EGC based as Table 250.122 amp ratings for OCPD's specified for just that purpose. There is no differentiation when the common ground planes intersect at the service main disconnect single point ground, but apply the same to a sub panel and there is a distinction between pipe and EGC as an earthing ground vs fault path condition. Is this not viable?

 

[jwelectric]

When using the water pipe as an electrode only the first five feet that enters the building can be used as the electrode or to bond other electrodes. If the grounding electrode conductor is connected to the first five feet and there is a meter, filter or similar device between this point of attachment and the point of entry then a bonding jumper is required to be installed around these devices.

If the grounding electrode conductor is connected between these devices and the point of entry of the water pipe then the only requirement to bond around these devices would be to conform to 250.104(A). In other words I could install another ?bonding? conductor to the water pipe at any convenient point and not bond around the water meter, filter or other devices.

When addressing things as a sealant used on the threads of water piping system how would a sprinkler system be handled? The same requirement requires us to bond the sprinkler system and is not a sealant used on the fittings of the sprinkler system?

I think that there is too much emphasis being put on the bonding around a water heater.
Give me some feed back on this installation. Non metallic pipe is used to enter the building but the interior of the building has a metal piping system. A bonding conductor (250.104(A) ) is installed to the underside of a sink and jumped from cold to hot.

 

[gndrod]

Where does 250.104(A)} specifically mention underside of a sink being bonded or jumpered? Also nylon and plastic supply hose is still being used in the residential industry. That is a major dielectric that still happens. Good point on old metallic sprinkler systems possibly being TFE taped. I have only seen piping with Rector Seal as used for NFPA 101 requirements.

 

[jwelectric]

Where does 250.104(A)} specifically mention underside of a sink being bonded or jumpered?

It doesn?t, that is just an example of bonding around a water heater.

250.104 Bonding of Piping Systems and Exposed Structural Steel.

(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).

The question I am seeking an answer to is the habit of bonding the hot and cold pipes together at the water heater. I have looked in every cycle of the NEC as far back as the 1962 cycle and can not find a requirement to bond the hot and cold pipes together.
I have heard of dielectric fitting at the heater, Teflon tape and nonmetallic supply lines but still no requirement to bond the two pipes together.

The only requirement in 250.104(A)(1) is that the point of attachment is to be accessible. The code panel was explicit in 250.53(D)(1) to require the bonding around such devices as meters and filters when the water pipe is being used as a grounding electrode. There has never been a requirement to bond around the water heater, meter or filter in 250.104(A).
Based on this lack of a requirement to bond around a water heater I contend that if there is continuity no bond is required regardless of the type of fittings or sealant used.
.

 

[gndrod]

jwelectric,
I agree with your statement right down to "I contend that if there is continuiity". If there is not continuity then all bets are off. Certainly there is no rule that specifies the jumper bond at the water heater, but can you list a more economical and accessible place to do the bond. Let me know and I will learn a little more about what's best. That's what makes anyone involved in our demanding trade a more knowledgeable and competitive tradesman. The WAC 296-46B mentioned earlier is an intelligent way of taking safety into account. The NEC is a diamond in the rough that needs polishing and I readilly support your direction to pursuing needed refinements. Maybe we can see your proposal in the 2011 cycle?

 

[jwelectric]

An old warehouse was renovated and turned into apartments. The water piping system is metal through out with dielectric unions on the water heaters in each unit.
This building has an 800 amp main but each unit is supplied with a 100 amp feeder.

What size jumper would you install across the hot and cold pipes in each unit?

I wouldn?t install any at all.

 

[gndrod]

3 ph? 4 wire?

 

[George Stolz]

An old warehouse was renovated and turned into apartments. The water piping system is metal through out with dielectric unions on the water heaters in each unit.
This building has an 800 amp main but each unit is supplied with a 100 amp feeder.

What size jumper would you install across the hot and cold pipes in each unit?

I wouldn?t install any at all.

If the hot water piping is part of a water piping system, and has no continuity, isn't it a violation of 250.104 not to bond them in?

I agree with your thought that the water heater isn't "the" spot for such bonding, but it's a good spot, since sinks may come and go, but the water heater location is less prone to change and inaccessibility.

One other thought: What if the hot becomes energized?

 

[jwelectric]

If the hot water piping is part of a water piping system, and has no continuity, isn't it a violation of 250.104 not to bond them in?

In 250.104(A) there is no requirement to insure that the water piping system has continuity, neither the fresh water supply nor any other water supply.
It is my opinion that the hot and cold water pipes installed in a building are all part of one system or in other words they are not two separate systems there.

One other thought: What if the hot becomes energized?

By what?
The only thing that I can see that would ever energize the hot water pipes would be a piece of equipment that would be bonded with the equipment grounding conductor installed with the circuit.

I think that this bonding of the hot and cold got started by someone that was over thinking something that just wasn?t there.
I was hoping that someone could find something in the back issues of the ROPs that would give information on this issue one way or the other.

The only reason for bonding the water pipes based on the service to start with would be due to the chlorine or bromating compounds that is added to the water and the fact that some pipes are used as grounding electrodes. These chemicals could conduct current from one house to the other.
The water pipes that are not connected to a public or shared water system I see no need for all this bonding.

 

[gndrod]

jwelectric,
There is the triboelectric water flow static energy generation that is a concern in some facility systems and the uncomfortable little spark when touching a metal unbonded fixture. I would consider not gambling with code non-enforcement loopholes and insure that safety bonding will prevent any unwanted potentials to exist. JMO

 

[jwelectric]

5-235 Log #1834 NEC-P05 Final Action: Reject
(250.104(A)(1))
____________________________________________________________
Submitter: Mark T. Rochon, Mark J. Rochon Master Electrician
Recommendation: Revise as follows:
General Combination metal water piping system(s) separated by nonmetallic water piping system(s) where may become energized 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 the one or more grounding electrodes used.
Substantiation: Nonmetallic water piping systems are being inserted between our metal water piping system and today?s code is not recognizing these changes.
Panel Meeting Action: Reject
Panel Statement: The conditions indicated in the substantiation are already covered by 250.104(B) where there is not a complete metallic water piping system.
Number Eligible to Vote: 15
Ballot Results: Affirmative: 15
____________________________________________________________
5-236 Log #2432 NEC-P05 Final Action: Reject
(250.104(A)(1))
____________________________________________________________
Submitter: Robert P. McGann, City of Cambridge
Recommendation: Revise text to read as follows:
Metal water piping system(s) that is likely to be energized installed in or attached to a building or structure shall be bonded.
Substantiation: With much expanded use of plastic water piping system(s) isolating section of metal piping systems. This type of installation leaves contractors and inspectors what is required to be bonded.
Panel Meeting Action: Reject
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.
Number Eligible to Vote: 15
Ballot Results: Affirmative: 15

If I am reading these two proposals correctly then should a dielectric union or short piece of nonmetallic pipe be installed at the water heater then there would be no requirement to bond based on 250.66 to fulfill the requirements of 250.104.
Am I misreading something here?

 

[gndrod]

jwelectric,
No, but I hope you agree with the safety factor in my last reply.

 

[jwelectric]

As the NEC is not concerned with electrical charges such as walking across carpet and touching a door knob of sitting on furniture and getting shocked when going to the fridge then I don?t see where they would be concerned with the energy that would be produced by water flow.

What I am looking for is something that would substantiate an inspector requiring a bonding jumper to be installed between the hot and cold water pipes.

There are some inspectors in this country that feel that this is a requirement when installing a bonding conductor as outlined by 250.104 but I just can?t find anything that will substantiate this in the code.
By what rule could this be enforced?

 

[gndrod]

Doesn't seem like any from the NEC, but other NFPA safety requirements exist that can be plan specified. As I mentioned in some facilities there are environments that require bonding in volatile areas that may set off reactive hazards. (i.e. Anti-static bonding required in emergency wash stations in chemical plants, plating baths, etc.....)

 

[tom baker]

Washington State has a state code rule that says if the hot and cold of a metallic water piping system are bonding by a mixing valve then no jumper is needed on the water heater.
And we also don't have to bond isolated metal subs outs by code rule

 

[George Stolz]

Mike, great post.

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

Does anybody else get the impression they are adding an undue amount of inflection to make this statement hold water? I feel like they're blowing smoke up our butts.

What is the bonding of metal water pipes for at all, if they're perfectly content to not bond half of them? Does cold water create a shock hazard?

 

[gndrod]

Thanks George.

 

[jwelectric]

Mike, great post.
Does cold water create a shock hazard?

Maybe through an open neutral upstream of the cold water supply.
Remember that not all water supplies are like ours, some come from the city.