Quick Hits

Article 810 (Part 2 of 2)
Antenna Systems — Amateur & CB Transmitting Stations!

SLIDE 1 — Part III Overview & Conductor Sizing (810.51, 810.52, 810.53)
📡 OTHER SECTIONS THAT APPLY (810.51)
Amateur and CB transmitting/receiving antenna systems must comply with Part III PLUS 750.60(B) and 810.11 through 810.14.
📏 ANTENNA CONDUCTOR SIZE (810.52, Table 810.52)
Minimum AWG by max open span:
🔹 Hard-drawn copper → 14 AWG (<150 ft), 10 AWG (>150 ft)
🔹 Copper-clad steel, bronze, or other high-strength material → 14 AWG (<150 ft), 12 AWG (>150 ft)
🔌 LEAD-IN SIZE (810.53)
Transmitting station lead-ins must be at least as large as the antenna conductors in 810.52.

SLIDE 2 — Clearance on Building (810.54)
🏠 MOUNTING ON BUILDINGS
Transmitting antenna conductors (and lead-ins) attached to buildings must be:
🔹 Firmly mounted at least 75mm (3 in.) clear of the building surface
🔹 On nonabsorbent insulating supports (treated pins or brackets with insulators) having at least 75mm (3 in.) creepage AND air-gap distances
✅ Exception: lead-ins enclosed in a continuous metal shield grounded per 750.70 don’t need to comply. The grounded shield can also serve as a conductor.
💡 Creepage = shortest distance along the insulator surface. Airgap = shortest distance through the air to the building surface.

SLIDE 3 — Entrance & Accidental Contact (810.55, 810.56)
🚪 ENTERING THE BUILDING (810.55)
Unless protected by a continuous metallic shield grounded per 750.70, transmitting lead-ins must enter by ONE of:
1️⃣ A rigid, noncombustible, nonabsorbent insulating tube or bushing
2️⃣ An opening provided for the purpose, with conductors firmly secured and at least 50mm (2 in.) clearance
3️⃣ A drilled window pane
⚠️ ACCIDENTAL CONTACT (810.56)
Lead-ins to radio transmitters must be located or installed so accidental contact is DIFFICULT.

SLIDE 4 — Interior Separation (810.70) + Final Exam
🔌 SEPARATION FROM OTHER CONDUCTORS (810.70)
All conductors inside the building must be separated at least 100mm (4 in.) from electric light, power, or signaling circuit conductors, UNLESS:
1️⃣ A permanent audio system is installed per Article 640 Parts I and II
2️⃣ Portable/temporary audio systems are installed per Article 640 Parts I and III
3️⃣ The conductors are separated by a continuous, firmly fixed nonconductor

🧠 FINAL EXAM QUESTION FOR ARTICLE 810 (Part 2)
Q: Per 810.54, transmitting antenna conductors attached to buildings must be mounted at least how far clear of the building surface?
A) 1 in.
B) 2 in.
C) 3 in.
D) 6 in.
(Drop your final answer 👇)

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