Master Electrician Exam (NEC)Special Occupancies, Equipment, and ConditionsMedium
A master electrician is designing the electrical system for an indoor agricultural building used for housing poultry. The building has a potential for excessive dust and corrosive conditions due to animal waste. Which of the following wiring methods is generally NOT permitted in such a location according to NEC?
- AOpen wiring on insulators
- BType MC cable with a corrosion-resistant jacket
- CType UF cable
- DType NMC cable
Show answer & explanationAnswer & explanation
Correct answer: A. Open wiring on insulators
NEC Section 547.5(A) prohibits open wiring on insulators in agricultural buildings with excessive dust and corrosive conditions. This is due to the susceptibility of open wiring to damage and accumulation of corrosive substances, increasing fire and shock hazards.
Why the other options are wrong
- B. Type MC cable with a corrosion-resistant jacket is a suitable wiring method for such conditions, providing adequate protection.
- C. Type UF cable is permitted; it is designed for direct burial and offers excellent moisture and corrosion resistance.
- D. Type NMC cable is generally permitted in these locations, as it is corrosion-resistant and suitable for damp, corrosive environments.
Agricultural Building Wiring Restrictions
Specific NEC requirements for wiring methods in agricultural buildings, particularly those with corrosive or damp environments, to ensure safety.
- Corrosive and damp conditions are common.
- Wiring must be protected from physical damage and corrosion.
- Certain wiring methods are explicitly prohibited.
Memory trick: No open wires where the farm dust flies; corrosion's a foe, protect with wise ties!