Layout Requirements for High-Voltage and Low-Voltage Switchgear Rooms: Optimizing Space Arrangement and Safety Clearances
High-Voltage Switchgear Room
When the length of a high-voltage switchgear room exceeds 7m, two doors should be provided, preferably located at opposite ends. The access door for handling GG-1A type switchgear should be 1.5m wide and 2.5–2.8m high.
Recommended dimensions for operating aisles in front of fixed switchgear: 2m for single-row layout and 2.5m for double-row layout, measured from the front of the panels. When a large number of switchgear units are installed, the aisle width may be appropriately increased.
Generally, only high-voltage switchgear is installed in high-voltage switchgear rooms. However, when the number of cabinets is small (e.g., four or fewer), they may be placed in the same room as low-voltage distribution panels, but not facing each other. In single-row layouts, the clear distance between high-voltage switchgear and low-voltage panels should be no less than 2m.
For overhead outgoing lines, the minimum height from the outdoor line bushing to ground should be 4m, and the line suspension point should be no less than 4.5m above ground. The height of the high-voltage switchgear room should be determined based on the elevation difference between indoor and outdoor floors and the above requirements, with a typical clear height of 4.2–4.5m.
Cable trenches in the room should have a slope and sump pits for temporary drainage. Trench covers should preferably be made of checkered steel plate. Inspection pits beneath adjacent switchgear units should be separated by brick walls.
For distribution equipment supplying primary (critical) loads, fire-resistant barriers or partition walls with door openings should be installed at busbar segmentation points.
Low-Voltage Switchgear Room
Low-voltage switchboards are generally not installed against walls; the rear clearance should be about 1m from the wall. Protective panels should be provided at both ends if passages are present. When the number of switchboards is three or fewer, single-side maintenance against a wall is acceptable.
When the low-voltage switchgear room also serves as an on-duty room, the distance from the front of the switchboard to the wall should preferably be no less than 3m.
When the length of the low-voltage switchgear room exceeds 8m, two doors should be provided, preferably located at opposite ends. If only one door is installed, it should not open directly into the high-voltage switchgear room.
When the length of low-voltage switchgear exceeds 6m, there should be two exits behind the panels leading to the same room or another room. If the distance between two exits exceeds 15m, additional exits should be added.
For distribution equipment supplying primary (critical) loads from the same low-voltage room, fire-resistant barriers or partition walls should be installed at busbar segmentation points. Cables supplying primary loads should not run through the same cable trench.
The height of the low-voltage switchgear room should be coordinated with that of the transformer room, and generally follows these guidelines:
(1) Adjacent to a raised-floor transformer room: 4–4.5m
(2) Adjacent to a non-raised transformer room: 3.5–4m
(3) With cable entrance: 3m
