An electrical room is an integral part of a commercial or industrial facility. It plays a vital role in the electrical system’s safe operations and power distribution throughout the building.
Because of the delicate nature of the electrical equipment and wiring, electrical rooms must be designed and built to meet specific requirements. These include load calculations, clearances, and how electrical installations interact with other building systems to help ensure the safety of the facility’s occupants and the equipment.
Here, we take a closer look at what an electrical room is and what are the design requirements for one. We’ll also answer some common questions about electrical rooms to help subcontractors successfully complete their projects.
Table of Contents
What is an Electrical Room?
The electrical room is a room or space dedicated to housing all the sensitive electrical equipment in a facility for power distribution or communication purposes. They offer safe, accessible storage for sensitive, possibly dangerous electrical equipment. As a result, they make the operation and maintenance of circuitry much safer and more convenient.
Electrical rooms typically house medium- or low-voltage electrical distribution equipment, including electric switchboards, distribution boards, circuit breakers and disconnects, motor control centers, relays, transformers, busbars, fire alarm control panels, and distribution frames, switchgear fuse-switches, electrical panels, etc.
Working Space and Clearances
Working space holds a substantial role in an electrical room’s effective operation, maintenance, and repair. Adequate clearance must be available around equipment materials for employees’ safety during maintenance, repair, and installation activities.
The National Electrical Code (NEC) is a set of standards published by the National Fire Protection Association (NFPA) for the safe installation of electrical wiring and equipment to prevent fires and other electrical accidents. Electricians and contractors must be aware of the NEC to ensure that installations are safe, legal, and up to code.
Depth of working space
Table 110.26(A)(1) of the NEC states that the aisle space between low voltage installations (0-600 V) should be no less than 3ft to 4ft (0.9m to 1.2m). The distance between these installations depends on the presence of live wires on either side of the installations.
Source: up.codes
- 3 ft. if exposed live parts are on both sides of the working space effectively guarded by insulating materials.
- 3 1/2 ft if exposed live parts are on one side of the working space and grounded elements on the other. This includes walls made of concrete, brick, or tile.
- 4ft if exposed live parts are on both sides of the working space.
For moderate voltage installations (600-1000V), the aisle space required is even wider, ranging between 3ft to 5ft (0.9m to 1.5m). Even if safety enclosures or screens cover components, this rule still applies.
Width of the working space
The working space in front of electrical equipment must be at least as wide as the equipment itself, or 30 inches, whichever is greater. NEC also requires enough space for equipment doors or hinged panels to open at least 90 degrees.
Height of working space
The workspace should be clear and extend from the ground to a height of 2.0 meters (6 1/2 feet) or the height of the equipment, whichever is greater. Other electrical installation equipment or support structures, such as concrete pads located above or below the electrical equipment, may extend no more than 150 mm (6 in.) beyond the front of the electrical equipment.
Load Calculations
A deep understanding of the electrical consumption of a building or facility is key to ensuring smooth operation.
If an under-sized electrical service is facilitating the electrical requirements of a building, there won’t be enough power available to electrical appliances. Furthermore, there is the risk of overloading the service, leading to conductor heating, insulation breakdown, and eventually a fire hazard.
On the other hand, using an oversized electrical service for the building results in unnecessary costs. By conducting proper service load calculations, you can select equipment that can optimally handle your facility’s load and avoid overloading the system or incurring extra charges.
Coordination with other building systems
As per Article 110.26(E) of the NEC, there must be no piping, ducts, leak protection apparatus, or other foreign equipment installed within 6ft (1.8m) above or below the equipment to avoid unnecessary risks.
If any foreign systems such as mechanical or plumbing systems were to run above equipment in the electrical room, they would have to be above 6ft (1.8m) or the ceiling, whichever is lesser.
Foreign systems would be permitted to operate above the equipment under the condition that safeguards are in place to protect the electrical equipment from damage caused by condensation, leaks, or breaks in such foreign systems. Protection might be as simple as wrapping an HVAC duct with insulation or installing a drip pan below liquid transferring pipes.
