Quick Hits

Episode 4: Grounding, Chassis Bonding & Service Equipment (550.18 – 550.52)

SLIDE 1 (HOOK / COVER)

⚡ NEC Quick Hit: Grounding & Park Services (Part 4) ⚡

Isolating neutrals, chassis bonding straps, and 100-amp service equipment—let's finish Article 550! 👇

SLIDE 2 (NEUTRAL ISOLATION & CHASSIS BONDING)

Keeping Neutrals Isolated:

• Neutral Isolation: The grounded circuit conductor (neutral) must be completely insulated from equipment enclosures and the mobile home frame inside the home. Bonding screws, straps, or buses in panelboards and appliances must be removed and discarded.

• Chassis Bonding: All exposed non-current-carrying metal parts must be bonded to the panelboard grounding bus, with a bonding conductor connected to an accessible terminal on the chassis using solid copper, 8 AWG minimum.

• Metal Skins & Roofs: Metallic roofs and exterior skins are considered bonded if metal panels overlap with fasteners and lower panels are secured to the chassis by metal straps.

SLIDE 3 (SERVICE EQUIPMENT & FEEDER RATINGS)

Site Supply Standards:

• Service Equipment Rating: Mobile home service equipment located outside the home must be rated at not less than 100 amperes at 120/240 volts and mounted within sight of the home.

• Mounting Height: The bottom of the disconnect enclosure must be at least 600 mm (2 ft) above grade, with the operating handle max 2.0 m (6 ft 7 in.) high.

• Feeder Capacity: Feeder conductors must have an ampacity of not less than 100 amperes.

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

Never tie the neutral and equipment grounding bus together inside a mobile home panelboard unless it is designated as service equipment on a permanent foundation per Section 550.51(B)!

💬 Save this post for your final code review on Mobile and Manufactured Homes!

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