This is a new KB home in phase 2 development. I found no bonding clamp or #6 copper conductor. Black steel gas piping in attic. I drove around phase 1 and phase 2, I could not find a single gas supply that was bonded. My understanding of NEC 250.104B was that metal gas piping should be bonded to the buildings grounding electrode system.
The painted pipe in the pictures is metal also.
Is it possible that the county is not requiring gas piping to be bonded?
What are you all thoughts?
Thanks
Aric
Metal piping systems that are likely to become energized must be bonded. This includes Gas piping, compressed air lines, vacuum system piping, medical gas piping and the like. Bonding the piping systems ensures that if they become energized, then the overcurrent device supplying the circuit associated with these systems will trip.
Did you locate a circuit that would be susceptible to causing the piping to become energized?
Its not always bonded at the exterior. I typically find them bonded in the garage or in the attic above the exterior wall where they enter.
Do you have a picture of the interior of the panel? You would likely see a conductor terminated at the grounding bus
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Yes I did see a conductor terminated at the grounding bus bar.
Thanks for your help.
In a perfect world, all conductive materials not specifically intended to carry current under normal operation would be bonded together to form a single conductive plane and there would be no possibility of a potential between that plane and Earth. However, we live in a world that is far from perfect.
There are people who do not think that gas lines should be bonded. That includes people who are charged with creating and enforcing building codes. The NEC is not an actual code. It is a model that can be adopted in part or in whole by a governing authority. Furthermore, that authority is delegated to groups and individuals who are charged with interpreting and enforcing applicable building codes. The net effect being that there are no building codes that are universally adopted, interpreted, and enforced.
It is certainly possible for a local inspection authority not to require gas lines or anything else) to be bonded to anything else. There is a common misconception among building officials and others that bonding gas pipes is somehow unsafe.
Contrary to popular believe, bonding all metal components that are not intended to carry current under normal circumstances is not only safe, it enhances overall safety. Metal gas pipes create a Faraday shield. Proper bonding greatly reduces any chance of ignition.
As a home inspector, your job is not to redesign any system or component in a house. You are, of course, entitled to your opinion, but if an installation was approved by the local building authority, then your opinion isn’t going to carry much weight.
A common argument I hear from home inspectors is that there is no local governmental building department with authority to allow or disallow anything. In those cases, the utility company and fire marshal have the authority to allow or disallow an installation.
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Thanks for your input.
Is the black steel gas piping considered bonded since it’s connected to the furnace though the equipment grounding conductor?
Yes.
The black steel gas piping is generally considered bonded to the equipment, a furnace with a adequately sized equipment grounding conductor or (EGC).
I hope I explained myself properly.
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A Faraday Shield/Cage, is a ‘conductive enclosure’ that blocks electromagnetic fields.
It protects objects inside the cage from external electromagnetic radiation and also prevents the object inside from emitting electromagnetic radiation outside the cage
George Wells, “Your The Best!”
Black gas pipe does not require a separate connection the grounding electrode system. As mentioned the equipment grounding conductor for the branch circuit feeding the gas equipment is all that is required to bond the gas pipe.
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National Electrical Code (NEC) section 250.104(B), the equipment grounding conductor (EGC) for the branch circuit that likely energizes the gas equipment is sufficient to bond the gas piping.
Great reply.
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Here’s the actual code section. You can bond it if you like with a separate conductor but it is not required.
250.104(B) Other Metal Piping.
If installed in or attached to a building or structure, a metal piping system(s), including gas piping, that is likely to become energized shall be bonded to any of the following:
(1) Equipment grounding conductor for the circuit that is likely to energize the piping system
(2) Service equipment enclosure
(3) Grounded conductor at the service
(4)Grounding electrode conductor, if of sufficient size
(5)One or more grounding electrodes used, if the grounding electrode conductor or bonding jumper to the grounding electrode is of sufficient size The bonding conductor(s) or jumper(s) shall be sized in accordance with Table 250.122, and equipment grounding conductors shall be sized in accordance with Table 250.122 using the rating of the circuit that is likely to energize the piping system(s). The points of attachment of the bonding jumper(s) shall be accessible
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I find a lot of bonding clamps in the wall behind a blank plate. Usually in the garage opposite the meter.
Ok. I understand now. The reason I was confused is because I’ve inspected new homes in other subdivisions with the same gas furnace configuration in the attic, but will have a bonding clamp on the exterior.
It’s important to be able to distinguish when an additional bonding jumper is required and when it isn’t. If the gas system is all threaded black gas pipe then no bonding jumper is required. Although not required it is permitted to provide an additional bonding jumper to the pipe.
If there is CSST involved then a bonding jumper may be required depending on the manufacturer of the CSST.
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No usually a different plate than the ufer with a clamp attached to the gas line
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