Master Electrician Exam (NEC)Special Occupancies, Equipment, and ConditionsHard
A master electrician is inspecting the electrical system of a new mobile home. The mobile home is supplied by a 120/240-volt, 100-ampere service. What is the minimum size copper supply cord required for this mobile home, according to NEC?
- ANo. 1 AWG
- BNo. 4 AWG
- C2/0 AWG
- DNo. 2 AWG
Show answer & explanationAnswer & explanation
Correct answer: D. No. 2 AWG
NEC Section 550.10(B) specifies that for a 100-ampere mobile home service, the supply cord shall be rated at not less than 100 amperes, and if of copper, shall be No. 2 AWG. This ensures adequate current-carrying capacity for the mobile home's electrical needs.
Why the other options are wrong
- A. No. 1 AWG copper is rated for 110 amps (60°C) or 130 amps (75°C), which would be acceptable but is larger than the minimum required.
- B. No. 4 AWG copper is typically rated for 85 amps (60°C) or 95 amps (75°C), which is insufficient for a 100-ampere service.
- C. 2/0 AWG copper is significantly oversized for a 100-ampere service, rated for 175 amps (75°C).
Mobile Home 100A Supply Cord
The minimum required size for a copper supply cord for a 100-ampere mobile home service, as specified by the NEC, to ensure safe and adequate power delivery.
- Specific to mobile home services.
- NEC 550.10(B) governs this.
- Ensures proper ampacity for the service rating.
Memory trick: One hundred amps for the mobile home's hum, No. 2 copper, for power to come!