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The Home Inspector

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Bonding your CSST gas lines: Minnesota updates its rules

I last blogged about CSST bonding nearly three years ago. There have been a few changes to CSST bonding rules since then, and there is still a lot of bad information circulating about CSST bonding and safety requirements, so it's time for an update on that topic.

First, a primer on CSST, which stands for Corrugated Stainless Steel Tubing. If you own a newer home or you've recently had gas lines added to your home, there’s a good possibility that CSST was used. This is a relatively new, flexible material that is approved for the distribution of natural gas inside of homes. The best analogy I can think of to describe this material is that CSST is to steel gas pipes what PEX is to copper tubing, or Romex® is to rigid metal conduit.

CSST needs to be bonded. The most common issue that home inspectors find with CSST is a system that hasn’t been properly bonded. When CSST is installed without being properly bonded to current standards, there is an increased risk for damage to the material from a nearby lightning strike. When CSST is damaged, it can leak gas and cause an explosion and/or a fire. To the best of my knowledge, all manufacturers of CSST began implementing specific bonding requirements around 2007.

What about existing installations? Building codes have something called "grandfathering." This means that if something was installed to code, it’s still a code compliant installation today, even if the codes have changed significantly. The nice thing about being a home inspector is that we don’t need to get hung up on code requirements. If something is deemed unsafe due to a change in accepted residential construction standards, our Standards of Practice requires us to report on it.

If CSST was installed to code in 2005 and the manufacturer didn’t have any special requirements for bonding at the time it was installed, the installation still meets code today. That won't stop me from recommending the system be bonded to today’s standards. The manufacturers of CSST have changed their installation requirements because they’ve learned that the old methods weren’t good enough.

What does proper bonding look like? There needs to be a separate bonding wire connected either to the rigid gas piping before the CSST, or directly to one of the CSST nuts. This is needed any time CSST is installed, even if it's just a small amount. The diagram below shows an example of what this would look like when properly installed to today’s standards.

Bonding CSST diagram

The photo below shows an example of CSST bonded at the exterior of the home, with the bonding clamp connected to the CSST nut.

CSST Bonded at nut

The other end of that wire shown above went into the main electric panel. The video below, produced by Gastite, shows a couple examples of how to properly bond CSST.

While the old method for bonding CSST required a connection at the main electric panel, this is no longer required in Minnesota. Minnesota's 2015 Fuel Gas Code uses the 2012 International Fuel Gas Code, which requires CSST to be bonded anywhere along the electrical service grounding electrode system. That means that the bonding conductor for CSST can be connected to the metallic water piping coming into the home, a ground rod at the exterior, or anywhere else on the service grounding electrode system. This change makes it much easier to properly bond CSST. To view the current requirement, click the following link to view Chapter 3 of the 2015 Minnesota Fuel Gas Code, and scroll all the way down to the bottom to view section 310.1.1.

Some manufacturers of CSST offer a product with a black outer "arc-resistant" jacket, which is designed to show that it's an arc-resistant product. Two such examples of these products are CounterStrike and FlashShield. While the manufacturers of these products do not require special bonding, the Minnesota Fuel Gas Code makes no exception to the bonding requirements for these products. They still need to be bonded. For more info on that topic, check out this document on CSST bonding from Pro-Flex.

How can you know if you have CSST in your home? Look for flexible tubing with a yellow or black jacket that covers the ridges. About 99% of the CSST I've seen has a yellow jacket. This material is not to be confused with an appliance connector, which might have a yellow coating that follows the contours of the ridges. The photo below shows the two different materials.

CSST vs Gas Connector

The bottom line is that if you have a home with CSST, you should make sure it’s properly bonded to today’s standards, regardless of whether the installation "met code" when it was originally installed. Also, if your electrician tells you that bonding the CSST may increase the risk of a lightning strike, simply thank them for their time and call a different electrician.

Additional Information on CSST and bonding

Also, here's an old news clip with me talking to Kare 11 news about CSST bonding:

Author: Reuben SaltzmanStructure Tech Home Inspections


Should home inspectors recommend upgrading to new AFCIs? No.

Arc-Fault Circuit-Interrupters are relatively new electrical safety devices that first appeared in the 1999 National Electric Code. AFCI devices look very similar to GFCI devices, in that they have a test button and a reset method, and they come in the form of circuit breakers, receptacles, or stand-alone devices. The big difference between the two is that GFCI devices are designed to prevent people from getting electrocuted, while AFCI devices are designed to prevent fires. For an excellent in-depth discussion of AFCIs, check out Douglas Hansen's article, AFCIs Come of Age

Arc Fault Circuit Breakers

The 1999 National Electric Code required AFCI protection for branch circuits containing bedroom receptacle outlets, with the requirement taking effect on January 1st of 2002. Since then, AFCI requirements have been expanded many times, to the point where AFCI protection is now needed for "all 120-volt, single-phase, 15- and 20-ampere branch circuits supplying outlets or devices installed in dwelling unit kitchens, family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, laundry areas, and similar rooms." The NEC defines an "outlet" as "A point on the wiring system at which current is taken to supply utilization equipment." In my words, the NEC definition of an outlet is a place where power is provided to do work.

Side note: If you read my inspection reports, blogs, or anything else that I write, when I say "outlet" I mean the same thing that the rest of Minnesota calls an outlet; that thing in the wall that we plug cords into.

The 2011 NEC also had a section that took effect on January 1, 2014, requiring AFCI protection for any new or replacement outlets. I blogged about that topic right after this requirement went into effect.  Click this link for details on that topic: New Electrical Safety Requirement: AFCI Protection for Replacement Outlets

To put it simply, AFCI protection is needed all over the place in new homes, it's needed any time new outlets are installed, and I expect the requirements for AFCI devices to keep expanding until everything is AFCI protected. That's certainly the direction things are headed.

So back to the title of this post...

Most home inspectors already recommend adding GFCI protection for the areas where people are most likely to get electrocuted, so shouldn't we also start recommending AFCI protection for the majority of the 120-volt branch circuits within a home?

I say no.

Safety is important, but safety benefits need to outweigh the costs to justify upgrades. I have no problem telling my clients to add GFCI protection because it's an easy call to make. GFCI devices add a lot of life safety for a small price; usually $10 - $15 for a GFCI outlet, plus a little bit of work that I consider to be a good "starter" electrical project.

On the other hand, I would never recommend installing a sprinkler system in an existing home, because I believe the cost of the sprinkler system would outweigh the added level of fire safety.

I feel the same way about AFCIs; they don't offer enough added safety to justify the cost. Adding AFCI protection for an entire branch circuit typically requires the installation of a AFCI circuit breaker. These circuit breakers cost about $30 - $50 each, and installing them means replacing existing circuit breakers, which I don't consider to be a good "starter" electrical project. Additionally, many older electrical panels will not accommodate AFCI circuit breakers, and multiwire circuits present additional challenges.

What about older generation AFCIs?

As mentioned in Douglas Hansen's article referenced above, the first generation of AFCI devices really weren't all that useful. They weren't exactly defective, but they also didn't do a great job of preventing fires because they were only capable of detecting parallel arcs, which are uncommon. These older AFCI devices could be found in homes built between 2002 and 2008. Newer generations of AFCI devices, called "combination" AFCIs, are far more effective at preventing fires.

There are plenty of home inspectors who tell their clients to replace the old generation of AFCI devices with new combination AFCI devices, but I don't. I think it's inconsistent to recommend replacing old AFCI devices with new ones if I'm not also recommending AFCI protection be added throughout pre-2002 built homes.

Author: Reuben SaltzmanStructure Tech Home Inspections


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