New CSST Bonding Question

[kurt]

That's reasonable and smart.

[Jim Katen]

Someone posted a link in TIJ (I think it was in here anyway) about lightening blowing up a house with black pipe.

Anyone know where that is?

I don't remember that, but it wouldn't be surprising. A direct lightning hit will tend to do that with any pipe.

[Marc]

Someone posted a link in TIJ (I think it was in here anyway) about lightening blowing up a house with black pipe.

Anyone know where that is?

I don't remember that, but it wouldn't be surprising. A direct lightning hit will tend to do that with any pipe.

I disagree. Provide a high level of conductance to the earth and the power developed in it is nil. Iron pipe provides that conductance, CSST does not.

Marc

[kurt]

So, you're saying iron pipe is immune to direct lightning strikes? You really think it's magic and nothing bad happens?

[inspector57]

CSST in some climatic regions is pretty good stuff, with no leaks if installed properly, no rust, and robust enough for general service. To read the PR stuff it is better than rigid iron pipe in earthquake prone areas (not something I am familiar with). But when you add in lightening, it becomes enough of a problem to be concerned.

Most builders here quit using it years ago, probably because of the liability and perceived problems to consumers since it was getting a bunch of press.

The north Texas area provided the perfect storm as a test bed.

Builders were using the stuff almost exclusively in thousands of two story mcmansions with soaring roof lines built in the middle of a flat prairie.

All of the CSST pipe and metal vent stacks and metal chimneys of the gas equipment was located in the attic 30 to 40 feet in the air in and area that has just a little less lightening than coastal Florida.

The houses look like a lightening rod experiment.

Lots of houses burned to the ground before the fire department could respond from a lightening strike that normally would have been just minor damage.

There are no real statistics because the fire departments do not report on this separately from other types of lightening damage. But it was enough of a problem that class action lawsuits were settled and millions were paid out to provide additional bonding.

CSST has been a problem for years and will continue to be a problem for years to come but only a big problem in lightening prone areas.

[Marc]

So, you're saying iron pipe is immune to direct lightning strikes? You really think it's magic and nothing bad happens?

It's not magic but yes, it's practically immune because of its cross sectional mass. Lightning rods are similarly constructed in regard to mass but without the lengthwise hole and they take direct strikes. Cables intended for conducting lightning currents from rod to earth don't have as much mass as iron gas pipe and they do what they were intended to do.

Reduce the conductivity enough in any way such as reducing the cross sectional area of the conducting components and it'll reach the point where it can't take direct strikes anymore. Reduce it further to about what CSST is and it can't even conduct the current without fail.

Marc

[Douglas Hansen]

The intent of bonding CSST is protection from damage against indirect lightning strikes, not a direct hit. The idea is that if the earth on which a building sits has an elevated voltage from a nearby lightning strike, the voltage potential of the metal in the building will be elevated equally if all that metal is bonded together. That in turn lessens the chance of an arc between metals having differing potentials.

The bonding requirement for CSST, with its mandate for a #6 conductor, is only found in plumbing and mechanical codes, such as NFPA 54, the UMC, UPC, etc., and not in the electrical code. The electrical code only looks at bonding of gas to complete a fault current path, and allows the size of the bonding to be as small as the equipment grounding conductor of the circuit that could energize the piping. As Marc said earlier, it is about protection from electrical energy that has the utility as its source, not a lightning strike.

That said, there is a great deal of inconsistency within the electrical code on the required sizes and intent of bonding. In my own building department experience with high rise structures, I typically find bonding requirements that go well beyond the NEC minimums.

The NEC is not about protection from a direct lightning strike. Lightning protection is an entirely separate matter. Facilities with lightning protection systems typically have passive NFPA 780 systems with air terminals, down conductors, and other components that are both elevated above and independent of the electrical systems and metallic components of a building.

The bigger problem with CSST is poor installation practices. A part of the ANSI standard that governs CSST is that the worker be certified in the installation. For a few years, that kept CSST off the shelves of the big box home improvement stores and it was only available through plumbing supply houses where reps could stock it in return for holding training classes and providing certifications for installers. Sadly, that is not the case for many brands of CSST today, and it can be purchased by anyone. Lip service is paid to the ANSI standard by including a fill-in-the-blanks certification quiz that the purchaser is supposed to file. I anticipate that the greater threat to the future marketplace for CSST is not lawyers sifting through the ashes of a house hit by lightning, but insurance companies who will tire of lawsuits for shoddy installations.