Quick Hits

⚡ NEC Quick Hit: Industrial Machinery (Article 670) ⚡ 

CNC mills, automated assembly lines, and factory control cabinets—welcome to Article 670! How do you size supply conductors, overcurrent protection, and surge devices for packaged industrial machines? Let's break down the rules! 👇

SLIDE 2 (NAMEPLATES & FAULT CURRENT RULES) What Must Be Marked on the Machine:

• Mandatory Nameplate: Attached to the outside of the main control enclosure detailing voltage, phase, frequency, full-load amps (FLA), largest motor rating, and the short-circuit current rating (SCCR).

• The SCCR Mandate: Industrial machinery shall not be installed where the available fault current exceeds its marked SCCR. The available fault current must also be legibly field-marked on the machine per Section 110.21(B)!

SLIDE 3 (SUPPLY CONDUCTORS, DISCONNECTS & SURGE) Sizing Wire, Cutoffs, and Safety Interlocks:

• Supply Conductor Sizing: Ampacity must be at least 125% of all resistance heating loads + 125% of the highest rated motor + the sum of all other motors/loads operating simultaneously.

• Disconnects: Every machine requires an individual disconnect (NFPA 79 caps handle height at 6 ft 7 in.).

• Surge Protection: Industrial machinery equipped with safety circuits must have surge protection (SPD) to protect safety interlocks!

SLIDE 4 (WRAP-UP) 💡 Apprentice Pro-Tip: 

The marked full-load current on a machine nameplate already accounts for motor duty cycles and simultaneous operating loads. Always check the nameplate first before pulling your feeder conductors!

💬 Save this post for your next factory automation or industrial hookup! 🔗 

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