Ground and Bond… James Bond
Grounding and Bonding… such a mysterious world. Often misunderstood and miss applied. Do you have your Bond shaken or stirred?
Now for my little rant- I really think we should call grounding and bonding “Earthing and Bonding”. I think this would clear up a lot of confusion and maybe help people properly understand the two main functions.
So on a recent home inspection I can across a funny little example of misapplied grounding and bonding (earthing and bonding
).
Here we have a wood stove that was connected to grounding conductor (bonding) that makes you wonder what they were thinking or were they planing to change it out? Who knows but I do know that a wood stove does not need to be bonded to the electrical system. A grounding (bonding) conductor of a type specified in 250.118 is to remove potentially dangerous voltage from any ground faults of metal parts such as electrical raceways, cables, enclosures, equipment or any electrically conductive metal water piping system such as metal sprinkler piping, metal gas piping, other metal-piping systems, and exposed structural steel members that may be likely to become energized. Remember the earth is not to be considered as an effective ground-fault current path.
Then on the exterior we have an old auxiliary electrode which was never a great idea when it came to bonding the communication systems. Current requirement are that these systems should be connected to an Intersystem Bonding Terminal (IBT).
2017 Code Language:
250.94 Bonding for Communication Systems.
Communications system bonding terminations shall be connected in accordance with (A) or (B).
(A) The Intersystem Bonding Termination Device. An intersystem bonding termination (IBT) for connecting intersystem bonding conductors shall be provided external to enclosures at the service equipment or metering equipment enclosure and at the disconnecting means for any additional buildings or structures. If an IBT is used, it shall comply with the following:
(1) Be accessible for connection and inspection.
(2) Consist of a set of terminals with the capacity for connection of not less than three intersystem bonding conductors.
(3) Not interfere with opening the enclosure for a service, building or structure disconnecting means, or metering equipment.
(4) At the service equipment, be securely mounted and celectrically connected to an enclosure for the service equipment. to the meter enclosure, or to an exposed non-flexible metallic service raceway, or be mounted at one of these enclosures and be connected to the enclosure or to the grounding electrode conductor with a minimum 6 AWG copper conductor.
(5) At the disconnecting means for a building or structure, be securely mounted and electrically connected to the metallic enclosure for the building or structure disconnecting means, or be mounted at the disconnecting means and be connected to the metallic enclosure or to the grounding electrode conductor with a minimum 6 AWG copper conductor.
(6) Tire terminals shall he listed as grounding and bonding equipment.
Exception: In existing buildings or structures where any of the intersystem bonding and grounding electrode conductors required by
770.1(B)(2), 800.100(B)(2). 810.21(F)(2). 820.100(B)(2). and 830.100(B)(2) exist, installation of the intersystem bonding termination is not required. An accessible means external to enclosures for connecting intersystem bonding and grounding electrode conductors shall be permitted at the service equipment and at the disconnecting means for any additional buildings or structures by at least one of the following means:
(1) Exposed non-flexible metallic raceway
(2) An exposed grounding electrode conductor
(3) Approved means for the external connection of a copper or other corrosion-resistant bonding or grounding electrode conductor to the grounded raceway or equipment
Informational Note No. 1: A 6 AWG copper conductor with one end bonded to the grounded non-flexible metallic raceway or equipment and with 150 mm (6 in.) or more of the other end made accessible on the outside wall is an example of the approved means covered in 250.94. Exception item (5).
Informational Note No. 2: See 770.100. 800.100. 810.21. 820.100. and 830.100 for intersystem bonding and grounding requirements for conductive optical fiber cables, communications circuits, radio and television equipment. CATV circuits and network-powered broadband communications systems, respectively.
(B) Other Means. Connections to an aluminum or copper busbar not less than 6 mm thick × 50 mm wide (1/4 in. thick × 2 in. wide) and of sufficient length to accommodate at least three terminations for communication systems in addition to other connections. The busbar shall be securely fastened and shall be installed in an accessible location. Connections shall be made by a listed connector. If aluminum busbars are used, the installation shall also comply with 250.64(A).
Exception to (A) and (B): Means for connecting intersystem bonding conductors are not required where communications systems are not likely to be used.
Informational Note: The use of an IBT can reduce electrical noise on communication systems.
So in this example we have both bad earthing (grounding) and bonding. Remember electricity does not care what we think, it will do what it will do and we need to design our systems to handle this.
If you find any errors or have additional information that would expand on any code, building standards or manufacturer requirements please let me know.
NCW Home Inspections, LLC is a Licensed Washington State Home Inspection service located in Wenatchee Washington serving Chelan County, Douglas County, Kittitas County, Okanogan County and Grant County Washington and the cities of Wenatchee, Leavenworth, Cashmere, Oroville, Cle Elum, East Wenatchee, Quincy and many more…
Your Wenatchee and Chelan Professional Real Estate, Home and Structural Pest Inspection Service
Coordinator & Instructor- Fundamentals of Home Inspection- Bellingham Technical College
Former WA Home Inspector Advisory Licensing Board
www.ncwhomeinspections.com 509-670-9572
You can follow me on Facebook, Twitter, Google+ and on my website Blog.
If you find any errors or have additional information that would expand on any code, building standards or manufacturer requirements please let me know.
NCW Home Inspections, LLC is a Licensed Washington State Home Inspection service located in Wenatchee Washington serving Chelan County, Douglas County, Kittitas County, Okanogan County and Grant County Washington and the cities of Wenatchee, Leavenworth, Cashmere, Oroville, Cle Elum, East Wenatchee, Quincy and many more…
Your Wenatchee and Chelan Professional Real Estate, Home and Structural Pest Inspection Service
Coordinator & Instructor- Fundamentals of Home Inspection- Bellingham Technical College
Former WA Home Inspector Advisory Licensing Board
www.ncwhomeinspections.com 509-670-9572
You can follow me on Facebook, Twitter, Google+ and on my website Blog.
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