Mike Dolt Enterprises
Mike Dolt Enterprises
User: Keep It Simple Simon, Location: California
Asked on: Friday, March 7, 2025 at 2:52 pm EST
Answered on: Tuesday, March 11, 2025 at 9:32 pm EDT
Question: First post on this forum. I spent over 20 years in the industry as an industrial, then commercial, then residential and off grid systems electrician, however, have spent the last 10 years cosplaying as a plant engineer for a small manufacturing company, so some of my knowledge may have become dated. I do have a 2014 copy of the NEC which I do use to consult for questions I do not know the answers to already. On this topic, I need some help.Our business is preparing to move to a new location where the in-suite primary 480 volt 3 phase sub panel (along with a series of poorly laid out transformers and 208 volt sub panels) in mounted to a wall where we need to install pallet racking. I plan to consolidate and relocate the transformers and low voltage panels, but relocating the primary panel will be cost prohibitive unless absolutely necessary. Before I get too far down the rabbit hole laying out new locations and racking plans, I need some help determining relevant clearances we will need to maintain.I am aware of the 30" horizontal working space, and the 36" depth rules for sub panels, but I have not identified a required clearance from the side of the sub panel to the nearest frame of any pallet racking. Our rack guy says we need 36" of clear space from the side of any panels or transformers to the nearest rack structure, but he admits he does not know NEC.My own research on the topic shows that I need to provide a cross aisle and down aisle clearance of the rack structure in proportion to the highest point a load will be placed upon, but this does not differentiate between structure or utility devices. I know that I could install a sub panel with its side up against a wall as long as there is 30" of side to side working space, 36" of depth clearance, and if the ability to open the door of the sub panel 90 degrees or more is maintained.I also know that dry type transformers only require manufacturer specific clearances for ventilation.My questions to this forum are:Is our rack guy correct?Do I need to allow for 36" of rack structure to side of sub panel or side of transformer clearance?Appreciate the advice. Stay safe.
Welcome to the forum! It sounds like you've got a solid background. Let's break down the clearance requirements.
Short Answer
No, your rack guy is likely not entirely correct, but erring on the side of caution isn't a bad thing. You need to carefully differentiate between working space required by the NEC and general safety/operational access which is often a business decision (and can exceed NEC minimums).
Detailed Breakdown (Based on your 2014 NEC)
Working Space (110.26(A))
This is the crucial NEC requirement.
Width (110.26(A)(2))
Yes, the 30" width is correct in front of the equipment. It's measured from side-to-side of the equipment you might need to work on. You've got this right.
Depth (110.26(A)(1))
The 36" depth is likely correct, but it depends on the voltage to ground and the conditions opposite the equipment. For a 480V system, assuming the condition is "Exposed live parts on one side and grounded parts on the other side" or "Exposed live parts on both sides," the 36" is the right minimum. "Grounded parts" includes a concrete wall. If the opposite side is considered "Insulated" (unlikely in this scenario), the depth can be reduced to 3 feet (36 inches).
Height (110.26(A)(3))
The working space must be clear and extend from the grade, floor, or platform to the height specified in 110.26(E). Generally, it needs to be the height of the equipment or 6.5 feet, whichever is greater. So, no obstructions (including racking) within this space.
No Obstructions (110.26(B))
"The working space required by this section shall not be used for storage. When normally enclosed live parts are exposed for inspection or servicing, the working space, if in a passageway or general open space, shall be suitably guarded." This is important – racking cannot encroach on the required working space.
Specific Answers to Your Questions
Is our rack guy correct? Probably not exactly correct regarding NEC requirements. The NEC doesn't explicitly state a 36" clearance from the side of electrical equipment to racking structure outside of the defined working space. However, his recommendation may be based on practical considerations (discussed below) beyond the NEC.2. Do I need to allow for 36" of rack structure to side of sub panel or side of transformer clearance? Not necessarily for NEC compliance if you're maintaining the required working space in front of the equipment. You could place the racking right up against the side of the panel, provided the required working space in front is maintained and that there is no encroachment within 6.5 feet from the ground or the height of the equipment itself, whichever is higher.
Dry-Type Transformers
As you mentioned, clearances for dry-type transformers are generally manufacturer-specific for ventilation and cooling. Consult the transformer's nameplate and documentation. The NEC doesn't have a blanket minimum distance outside of the manufacturer's recommendations.
Important Considerations Beyond the NEC (Why Your Rack Guy Might Say 36")
Practical Access
Even if NEC compliant, 36" from the side of panels or transformers might be a good idea for general access for maintenance, inspections, and future modifications. It provides room to maneuver around the equipment without being cramped.
Accidental Contact/Damage
Pallet jacks, forklifts, and other equipment operating in the aisles can accidentally bump into or damage electrical equipment. A buffer zone reduces this risk.
Future Expansion/Changes
Leaving extra space allows for potential future expansion or reconfiguration of the electrical system or the racking layout without major disruptions.
Company Policy/Best Practices
Your company or insurance carrier might have internal policies or best practices that exceed the NEC requirements.
Recommendations
Prioritize NEC Compliance
Ensure you meet the minimum working space requirements in 110.26(A) – width, depth, and height. This is non-negotiable.
2.
Check Transformer Documentation
Review the manufacturer's documentation for the transformers to determine their specific ventilation clearance needs.3.
Consider Practicality
Weigh the cost of relocating the panel against the potential long-term benefits of having more accessible workspace.4.
Consult with Your Insurance Carrier
They may have specific requirements for electrical equipment clearances in a warehouse environment.5.
Err on the Side of Caution
If space allows, consider implementing your rack guy's 36" recommendation as a best practice for safety and accessibility. This might save you headaches down the road.6.
Document Everything
Keep detailed records of your layout, including measurements and justifications for your decisions, to demonstrate compliance.
In summary, you are not required* to have 36" on the side of the equipment as long as the working space in front of the equipment is maintained. However, that measurement may be required by your company/insurance or be wise to install if the space allows.
Hopefully, this clarifies the requirements! Don't hesitate to ask if you have more questions. Flag for review