Quick Hits

📱 EPISODE 3 — Article 242 (Part 3 of 4)

Wrapping Up Part II — SPD Grounding & Connections

SLIDE 1 — Type 4 & Number Required
🔧 TYPE 4 SPDs (242.18)

Type 4s are component-level devices — think of them as the guts that go INSIDE listed equipment. They can ONLY be installed by the equipment manufacturer. Not a field install situation.

🔢 NUMBER REQUIRED (242.20)
Wherever an SPD is used at a point on the circuit, it has to connect to every single ungrounded conductor at that point — no partial protection.

SLIDE 2 — Location & Connection Options
📍 LOCATION (242.22)
SPDs can be indoor or outdoor — but they must be made inaccessible to unqualified persons, UNLESS they're specifically listed for accessible locations.

🔌 CONNECTION BETWEEN CONDUCTORS (242.30)
An SPD can connect between any two of these:

Ungrounded conductor(s)

Grounded conductor

Equipment grounding conductor

Grounding electrode conductor

Important nuance: the grounded conductor and the EGC should only ever get bridged together THROUGH the SPD doing its job during an actual surge event — not as a permanent connection.

SLIDE 3 — Grounding Electrode Conductor Rules
🌎 GROUNDING ELECTRODE CONDUCTOR CONNECTIONS (242.32)

Outside of what's specifically addressed in Article 242, SPD grounding connections fall back to Article 250, Part III (general grounding electrode system rules).

Also — if a grounding electrode conductor is run inside a metal enclosure, it has to comply with 250.64(E) (bonding the metal enclosure at both ends).

That closes out Part II — everything under 1000V AC / 1500V DC is officially in the books! 📚

SLIDE 4 — Exam Question + CTA
🧠 TEST YOURSELF

Q: True or False — The grounded conductor and equipment grounding conductor may be permanently tied together at the SPD connection point, outside of a surge event.

A) True
B) False

(Answer in the comments 👇)

Next up: Part III — Surge Arresters for systems OVER 1000V. FOLLOW so you don't miss it ⚡ #JoshTheSparky #NEC2026 #ElectricianLife

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