- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
1.) NEC Section/Paragraph: 250.86(C)(2)
2.) Proposal/Comment Recommends: [deleted text]
3.) Proposal/Comment: (2) The structural metal frame of a building that is directly connected to a grounding electrode as specified in 250.52(A)(2) or 250.68(C)(2)(a), (b), or (c) shall be permitted as a bonding conductor to interconnect electrodes that are part of the grounding electrode system, or as a grounding electrode conductor.
a. By connecting the structural metal frame to the reinforcing bars of a concrete-encased electrode, as provided in 250.52(A)(3), or ground ring as provided in 250.52(A)(4)
b. By bonding the structural metal frame to one or more of the grounding electrodes, as specified in 250.52(A)(5) or (A)(7), that comply with 250.53(A)(2)
c. By other approved means of establishing a connection to earth
4.) Substantiation: If structural metal does not comply with the specifications given in 250.52(A)(2), then it is not an electrode. If it were an electrode, then 250.64(F) would inherently permit using it as a “conductor to interconnect electrodes.” This section’s apparent intent is to allow structural steel that does not offer an earthing connection, but still provides an unimpeachable and inexpensive bonding path, to interconnect grounding electrodes. It has the unintentional side effect of casting other grounding electrodes’ permission to interconnect into question – for example, can I connect a pair of clamps to a ground rod completely embedded in the earth for connection of a GEC and a bonding jumper to a second rod? The first sentence of this section makes that less certain, because it refers to a grounding electrode as one way to interconnect electrodes. That inherently implies that grounding electrodes not listed in this section are not allowed to interconnect electrodes (regardless of the permissive language employed.)
List items (a), (b) and (c) do not make any sense at all. If the purpose of this section is to allow a “non-grounding electrode” structural metal to act as a bonding jumper, what on earth does an earthing connection have to do with anything? Would you require a GEC to be earthed somewhere between the service and a grounding electrode? Are there any other bonding jumpers that have to be earthed between electrodes?
It makes sense for this section to place restrictions on how substantial the structural steel has to be to interconnect electrodes, because that would directly affect the ampacity of the structural steel. Those sort of additions would be logical to add to both 250.52(A)(2) and 250.86(C)(2). The existing list items do not affect ampacity or durability, but require a quizzical earthing connection of a bonding jumper. Please delete the referenced text, and allow this section to begin performing it’s intended purpose clearly.
2.) Proposal/Comment Recommends: [deleted text]
3.) Proposal/Comment: (2) The structural metal frame of a building that is directly connected to a grounding electrode as specified in 250.52(A)(2) or 250.68(C)(2)(a), (b), or (c) shall be permitted as a bonding conductor to interconnect electrodes that are part of the grounding electrode system, or as a grounding electrode conductor.
a. By connecting the structural metal frame to the reinforcing bars of a concrete-encased electrode, as provided in 250.52(A)(3), or ground ring as provided in 250.52(A)(4)
b. By bonding the structural metal frame to one or more of the grounding electrodes, as specified in 250.52(A)(5) or (A)(7), that comply with 250.53(A)(2)
c. By other approved means of establishing a connection to earth
4.) Substantiation: If structural metal does not comply with the specifications given in 250.52(A)(2), then it is not an electrode. If it were an electrode, then 250.64(F) would inherently permit using it as a “conductor to interconnect electrodes.” This section’s apparent intent is to allow structural steel that does not offer an earthing connection, but still provides an unimpeachable and inexpensive bonding path, to interconnect grounding electrodes. It has the unintentional side effect of casting other grounding electrodes’ permission to interconnect into question – for example, can I connect a pair of clamps to a ground rod completely embedded in the earth for connection of a GEC and a bonding jumper to a second rod? The first sentence of this section makes that less certain, because it refers to a grounding electrode as one way to interconnect electrodes. That inherently implies that grounding electrodes not listed in this section are not allowed to interconnect electrodes (regardless of the permissive language employed.)
List items (a), (b) and (c) do not make any sense at all. If the purpose of this section is to allow a “non-grounding electrode” structural metal to act as a bonding jumper, what on earth does an earthing connection have to do with anything? Would you require a GEC to be earthed somewhere between the service and a grounding electrode? Are there any other bonding jumpers that have to be earthed between electrodes?
It makes sense for this section to place restrictions on how substantial the structural steel has to be to interconnect electrodes, because that would directly affect the ampacity of the structural steel. Those sort of additions would be logical to add to both 250.52(A)(2) and 250.86(C)(2). The existing list items do not affect ampacity or durability, but require a quizzical earthing connection of a bonding jumper. Please delete the referenced text, and allow this section to begin performing it’s intended purpose clearly.
