shockinglystoopid277
Member
- Location
- Florida
- Occupation
- Rebellious Amish Electrician
I have a 22 foot tall single story building with structural steel frame and a metal hip roof. I wanted to limit roof penetrations so I routed the lightning protection down conductor on the outside of the building. I am not routing down conductors inside structural steel columns as noted in NFPA 780 section 4.9.13 and I am not using the structural steel columns as down conductors as noted in section 4.19.1.
Am I still required to have roof penetrations to bond strike termination devices (air terminals with interconnecting lightning protection main conductor in my case) per section 4.19.2?
Also, am I still required to bond the bottom of the columns around the perimeter of the building to my grounding electrodes (ground electrode system connected together via a ground ring in my case) per section 4.19.4? (note: I currently show a bond from structural steel to my main ground bar and a connection from my main ground bar out to the ground ring.)
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4.9.13 Down Conductors and Structural Columns. Down conductors coursed on or in reinforced concrete columns or on structural steel columns shall be connected to the reinforcing steel or the structural steel member at their upper and lower extremities.
4.19 Structural Metallic Systems.
4.19.1 General. The metal framework of a structure shall be permitted to be utilized as the main conductor of a lightning protection system if it is equal to or greater than 3∕16 in. (4.8 mm) in thickness and is electrically continuous, or it is made electrically continuous by methods specified in 4.19.3.
4.19.2 Strike Termination Devices.
4.19.2.1 Strike termination devices shall be connected to the structural metal framing by direct connection, by use of individual conductors routed through the roof or parapet walls to the steel framework, or by use of an exterior conductor that interconnects all strike termination devices and that is connected to the metal framework.
4.19.2.2 Where an exterior conductor is used in lieu of through-roof penetrations for the interconnection of strike termination devices, it shall be connected to the metal framework of the structure as follows:
(1) Conductors along a ridge at intervals not exceeding an average distance of 100 ft (30 m), as widely spaced as practicable and at each end in accordance with Section 4.9
(2) Perimeter roof conductors at intervals not exceeding an average distance of 100 ft (30 m), as widely spaced as practicable and at ends in accordance with Section 4.9
(3) Cross-run conductors at intervals not exceeding a distance of 150 ft (45 m) in lieu of the requirements of 4.9.8
4.19.4 Grounding Electrodes.
4.19.4.1 Grounding electrodes shall be connected to the structural metal framework at intervals around the perimeter averaging not more than 60 ft (18 m).
4.19.4.2 Connections shall be made as close as practicable to the base of the structural metal framework in accordance with the requirements in 4.19.3.
Am I still required to have roof penetrations to bond strike termination devices (air terminals with interconnecting lightning protection main conductor in my case) per section 4.19.2?
Also, am I still required to bond the bottom of the columns around the perimeter of the building to my grounding electrodes (ground electrode system connected together via a ground ring in my case) per section 4.19.4? (note: I currently show a bond from structural steel to my main ground bar and a connection from my main ground bar out to the ground ring.)
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4.9.13 Down Conductors and Structural Columns. Down conductors coursed on or in reinforced concrete columns or on structural steel columns shall be connected to the reinforcing steel or the structural steel member at their upper and lower extremities.
4.19 Structural Metallic Systems.
4.19.1 General. The metal framework of a structure shall be permitted to be utilized as the main conductor of a lightning protection system if it is equal to or greater than 3∕16 in. (4.8 mm) in thickness and is electrically continuous, or it is made electrically continuous by methods specified in 4.19.3.
4.19.2 Strike Termination Devices.
4.19.2.1 Strike termination devices shall be connected to the structural metal framing by direct connection, by use of individual conductors routed through the roof or parapet walls to the steel framework, or by use of an exterior conductor that interconnects all strike termination devices and that is connected to the metal framework.
4.19.2.2 Where an exterior conductor is used in lieu of through-roof penetrations for the interconnection of strike termination devices, it shall be connected to the metal framework of the structure as follows:
(1) Conductors along a ridge at intervals not exceeding an average distance of 100 ft (30 m), as widely spaced as practicable and at each end in accordance with Section 4.9
(2) Perimeter roof conductors at intervals not exceeding an average distance of 100 ft (30 m), as widely spaced as practicable and at ends in accordance with Section 4.9
(3) Cross-run conductors at intervals not exceeding a distance of 150 ft (45 m) in lieu of the requirements of 4.9.8
4.19.4 Grounding Electrodes.
4.19.4.1 Grounding electrodes shall be connected to the structural metal framework at intervals around the perimeter averaging not more than 60 ft (18 m).
4.19.4.2 Connections shall be made as close as practicable to the base of the structural metal framework in accordance with the requirements in 4.19.3.