Mike Dolt Enterprises
Mike Dolt Enterprises
User: oldguysparky, Location: Salt Lake City
Asked on: Wednesday, June 4, 2025 at 7:27 pm EDT
Answered on: Wednesday, June 4, 2025 at 7:44 pm EDT
Question: Article 110.31 states, "Electrical installations in a vault, room, or closet or in an area surrounded by a wall, screen, or fence, access to which is controlled by a lock(s) or other approved means, shall be considered to be accessible to qualified persons only. The type of enclosure used in a given case shall be designed and constructed according to the nature and degree of the hazard(s) associated with the installation."andarticle 495.35 (A) says, "Doors that would provide unqualified persons access to high-voltage (greater than 1000VAC) energized parts shall be locked."I have a scenario where an outdoor electrical yard is surrounded by a fence and the only access point is controlled by a lock. Do I still need to add an additional lock to the equipment access doors as well? The security personnel of the facility do access this yard and they are not qualified persons but it seems that 110.31 says if I have a fence, and the access is through a locked door the NEC considers this to be accessible to qualified persons only so I would not need to lock the back of switch gear or PTX panels that are greater than 1000VAC. Am I interpreting this correctly??
You've identified a common point of confusion when interpreting the NEC. Here's a breakdown of the code and how it applies to your scenario
Your Interpretation:
Your interpretation is partially correct, but needs further clarification. You're right to focus on the interplay between 110.31 and 495.35(A).
Here's a detailed analysis
Article 110.31 (Accessibility)
This section defines what "accessible to qualified persons only" means. A locked fence does generally meet this definition. The intent is to prevent unqualified persons from easily stumbling upon dangerous electrical equipment.
Article 495.35(A) (Door Locking)
This section specifically addresses high-voltage equipment (over 1000VAC). It mandates that "Doors that would provide unqualified persons access to high-voltage (greater than 1000VAC) energized parts shall be locked." This is a safety requirement to prevent accidental contact with high-voltage components.
The Conflict and Resolution
The apparent conflict arises from whether the locked fence completely satisfies the intent of 495.35(A). Here's the key consideration:
Purpose of the Second Lock
Article 495.35(A) is about preventing unqualified persons from accessing high-voltage parts.
Answering Your Question: Do you need the additional locks?
Likely, yes, you need to add an additional lock to the equipment access doors.Reasoning
The security personnel accessing the yard are not qualified persons. This is a crucial point. While the locked fence restricts general public access, it doesn't prevent unqualified facility personnel from entering.2. The intent of 495.35(A) is not fully met by the perimeter fence alone. The purpose of the section is to prevent unqualified personnel from accessing high-voltage energized parts. The fact that your security personnel, who are unqualified, have access to the yard means they have potential access to the doors on the equipment. Therefore, additional measures must be taken.
Key Takeaways & Recommendations
Err on the side of safety
When in doubt, prioritize safety and implement the additional locking mechanism.
Consult with a Qualified Electrical Engineer
Due to the specific circumstances and potentially high liability involved, consult a qualified electrical engineer familiar with the NEC and local codes. They can perform a hazard assessment and provide a definitive answer based on your specific installation.
Documentation
Keep thorough documentation of your safety measures, hazard assessments, and any consultations with engineers or inspectors.
In conclusion, while Article 110.31 provides a definition of "accessible to qualified persons only," Article 495.35(A) is very specific about the need to lock access points to equipment that is greater than 1000VAC, if unqualified persons have access behind the locked fence you will need to add the locks on the equipment Flag for review