Your critical power questions answered: Electrical systems and rooms

Learn best practices for designing electrical rooms and additional information from the webcast.

By Consulting-Specifying Engineer November 2, 2023

Electrical insights

  • Electrical rooms are sometimes an afterthought when it comes to building design and planning.
  • This shortsightedness can have unfortunate consequences on the cost, operations and flexibility of the electrical systems for the future.

NFPA 70: National Electrical Code (NEC) dictates the minimum amount of space needed around the equipment for access, operations, safety reasons and conduit installation. Together, with the actual equipment sizes, this defines the overall minimum dimensional requirements of the room.

Good engineering practice will often go beyond code in accommodating enhanced operation and maintenance of electrical equipment within the room. In addition, NEC does not cover the many important considerations in coordinating with architectural, structural, HVAC or fire protection disciplines.

During this webcast on Critical power: Electrical systems and rooms, several questions were left unanswered. Read responses from Yevgeniya (Jane) Baikadanova, PE, IPQ LLC here.

Question: A panelboard working clearance question: Could you use a shallow electrical closet to house panels, if the working clearance of 3 feet or 3.5 feet is only available in front of the panel, when the door(s) to the closet are open?

Answer: Yes, if the closet is only, say 2 feet or 2.5 feet deep? Yes, if you are meeting NEC 110.26 requirements.

Question: Opinion on stacked transformers?

Answer: You can stack them.

Question: The dedicated work space for electrical equipment, can it be shared with equipment for the same system? i.e., The step-down transformer being wall mounted above the panel it is feeding?

Answer: Not within dedicated electrical space. Nothing can be installed above the panel in the dedicated electrical space. It can be installed above the dedicated electrical space or next to it.

Question: What can an electrical engineer suggest when an electrical room ends up having a passing domestic water pipe, or ductwork when the contractors on-site make the executive decision to create their shortest paths in the building?

Answer: It is OK to install if they are avoiding dedicated electrical spaces. You can always suggest providing a tray and leak detector in case of the pipe breakage.

Question: A picture is worth a thousand words. Is there any push to include more visuals in the NEC?

Answer: That would be awesome. Not sure about the push.

Question: Are emergency lights required inside electrical rooms?

Answer: I believe International Building Code requires this in electrical (or equipment) rooms. It is a good idea to provide one when is not required.

Question: Can you stack transformers?

Answer: Yes.

Question: How can you comply with dedicated workspace when there is existing horizontal piping mounted on the wall when placing a new panel?

Answer: Good question. Either reroute the pipe or place the panel somewhere else.

Question: I see clearances in front of panelboards on all plans, but never transformers. Do transformers require the clearance? Also, how about fire alarm panels, lighting control panels, etc.

Answer: Yes. Any equipment operating at 1,000 V or less to ground and likely to require examination, adjustment, servicing or maintenance while energized needs to comply with NEC 110.26.

Question: If a water line is above panel and we install a drip pan, must that pan have leak detection?

Answer: Does not have to, but it is not a bad idea.

Question: If there is no option to route HVAC duct to another location and it needs to pass above electrical equipment, is code accept to have drain pan to comply code?

Answer: If it is above dedicated electrical space.

Question: Regarding this comment: “Telecom closet should be separate from the electrical closet,” are the closets in the same room?

Answer: No, you can have telecom and electrical equipment in the same room (if electrical is not Level 1 loads) if all clearances are met. Refer to TIA and BICSI.

Question: What says you cannot install a disconnect switch above a panelboard?

Answer: NEC 110.26 (E) (1) (a)

Question: Why is the disconnect above the panelboard a problem, its electrical gear in dedicated electrical space. What is wrong with that?

Answer: The issue that I see is the future access to running branch circuits from the panel to the loads.