Electrical control rooms provide dedicated spaces for the installation and operation of power distribution and communication equipment. These rooms are common and are an integral part of commercial or industrial facilities for the safe operations of electrical machinery. In this article, we review the benefits of electrical control rooms, requirements, construction methods, and a typical layout.
Benefits of Electrical Control Rooms
The presence of electrical control rooms in facilities offers several benefits, including:
- Isolation of electrical equipment from other processes in the factory. Equipment such as distribution boards, switchboards, and motor control centers are sensitive to moisture, dust, and corrosive elements. Having a dedicated room for them improves safety both for the equipment and personnel as the risk of accidental contact is minimized. Also, isolating electrical equipment helps to minimize noise on the factory floor.
- Centralization of electrical controls improves efficiency of industrial processes. Connections between units are less exposed and shorter, which speeds up communication. In addition, the tracking and monitoring of equipment performance is easier, as well as maintenance.
- Because the entire room is for electrical equipment, making changes to the equipment is easier. The room layout usually allows for expansion and contraction in terms of the equipment. This is done without interfering with other equipment on the factory floor.
Electrical Control Room Requirements
Due to the delicate nature of electrical equipment and wiring, the design of control rooms must meet requirements from the National Electric Code (NEC). A major requirement is to carry out proper service load calculations to have a deep understanding of the electrical consumption within the facility. Undersizing the electrical service means power would be insufficient. As a result, there will be service overloading that risks conductor heating, insulation breakdown, and eventual fire hazard. On the other hand, oversizing the electrical service incurs unnecessary costs. Apart from load calculations, NEC covers working space/clearance requirements, as well as requirements for interacting with other building systems to ensure safety.
Clearance and Working Space Requirements
To ensure effective operation, maintenance, and repair, there must be adequate clearance available for operators. Moreover, the NFPA 70, NEC, dictates some of these clearance requirements as follows:
- For low voltage installations (0 to 600 V), the aisle space should not be less than 3 to 4 ft, depending on the presence of live parts. If there are insulation guards for the exposed live parts on both sides of the installations, then the aisle space can be 3 ft. But, if both sides of the working space have exposed live parts without insulative guards, an aisle spacing of 4 ft is more appropriate. When one side of the installation has exposed live parts, and the other has grounded elements, an aisle spacing of 3½ ft will suffice.
- On the other hand, for moderate voltage installations (600 to 1000 V), aisle space should be in the range of 3 to 5 ft.
- The width of the working space in front of electrical equipment must be at least 30 inches or as wide as the equipment, whichever is greater. In addition, the NEC requires panel doors to open at least 90°.
- Workspace should extend from the ground to the height of the equipment or 6½ ft, whichever is greater. Moreover, support structures and other installations above or below the equipment may not extend beyond 6 inches in front of the equipment.
Requirements for Interacting with Other Systems
- Foreign systems running above equipment in electrical control rooms must be above 6 ft or the ceiling, whichever is lesser. Any system below this height results in unnecessary risks.
- Also, these foreign systems are only permitted to run above the electrical equipment if there are safeguards in case of failure. Some of these safeguards include drip pans below water pipes and insulation wrapping for HVAC ducts.
Typical Layout of Electrical Control Rooms
The layout of a control room depends on the demands for electrical equipment in a facility. In large setups, a separate building serves as a housing for electrical equipment. Whatever the case may be, the layout of electrical control rooms varies, with the following figure highlighting an example.
Courtesy: ResearchGate
When designing the layout for electrical control rooms, key considerations are as follows:
- The design should result from an appropriate task analysis method, such as hierarchical or link task analysis.
- Layout must not hinder verbal and non-verbal communication. Also, spacing around each unit should promote teamwork.
- Distance between workstations should be sufficient to avoid operators intruding into each other’s ‘intimate zones’. Usually, minimum spacing should be between 12 to 28 inches.
- Emergency exits should accommodate egress by the 99th percentile user. In addition, access and egress should be suitable for disabled operators.
- Layout should be effective whether there are low or high staffing levels.
- Circulation of personnel should be with minimum disruption to operators.
- The electrical control room layout should reflect the allocation of responsibility and supervision requirements. It should also contribute to the room’s ability to survive an emergency situation.
- If there are multiple electrical control rooms within a facility, adopting similar layouts ensures consistency.
Requirements for Designing Layout of Electrical Control Rooms
The following documents are necessary when preparing the layout of electrical control rooms:
- The floor plan of the control room.
- Layout, design, and plans for other systems such as HVAC, electrical, lighting, plumbing, etc.
- Relevant industry standards, ergonomic standards, control room safety, and security standards.
- Information on the types, numbers, and configuration of equipment and apparatus that will be installed in the room.
- Also, information on the control room team, as well as their communication and collaboration requirements.
Construction Methods
The construction approach for an electrical control room depends on its location. When electrical control rooms are within a facility, their construction and layout depend on other building systems. For an effective design and construction, the room should not be an after-thought; rather it should be part of the initial design. Otherwise, it would be better to introduce it as a separate building with a suitable design and layout. This is the case mostly in large facilities that have several electrical equipment. Prefabricated control rooms are an increasingly popular option when having electrical controls in a separate building. They offer several benefits including:
- Flexibility in size, design, and layout as they are not limited by the building facilities.
- Offers better protection to electrical equipment.
- Because the installation of the units, piping, and all apparatus happens in the shop, there is better quality control.
- Its construction and installation offer minimal disruption to the site.
- There is on-demand floor space for expansion or contraction.