Question regarding water collection pits in indoor cable trenches
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Dear seniors, the national standard GB 50054-95 for low-voltage power distribution design states: “Article 3.3.4 Cable trenches in power distribution rooms shall be equipped with waterproofing and drainage measures.” ” “ Articles 5.6.18 Cable trenches and wire tunnels shall be provided with waterproofing measures ； The slope of the drainage ditch at its bottom should not be less than 0.5%, and a sump should be provided ； The accumulated water can be pumped out through sump pits; when conditions permit, it can be directly discharged into the sewer system. ” May I ask: Is it necessary to have a sump in indoor cable trenches? Is it enough to just ensure good waterproofing? (In general, the interior of a distribution room is relatively dry and lacks any sources of water; under normal circumstances, is it only water from outside that seeps into the cable trench through the walls of the trench?) Is it sufficient to apply a layer of waterproof polyurethane building sealant at the joints in the trench walls? ) Also, does anyone have detailed information on how to construct sump pits for cable trenches? (There are two methods described in 94D164; I wonder if there are other reference books that provide more detailed instructions?) ）?
I’ve never seen indoor cable trenches used as sump pits. It is true that no pipes are allowed to pass through indoors. It shouldn’t be necessary to do it. I forgot the standard diagram for the sump pit. The manual isn’t here either: L
It is better to create a sump in the cable trench
Articles 5.6.18 should apply to outdoor cable trenches.
I’ve never seen water accumulation pits created in indoor cable trenches; however, water often accumulates in outdoor cable trenches. I think the standard refers to outdoor cable trenches
It depends on the actual situation. If the groundwater level is high, drainage pits are necessary outdoors, along with proper waterproofing measures. If a cement floor is installed in the cable trench, then there is no need for drainage pits; waterproofing measures indoors are sufficient. .
Based on years of construction experience, it is not necessary for projects in the north, while it is essential to have water collection pits in indoor areas of projects in the south; moreover, these water collection pits must not be connected to the outdoor drainage system.
Are there any regulations that specify more clearly the requirements for constructing sump pits? Is it still personal experience that suggests using a sump pit is better? Are there any other drainage measures (indoor cable trays)? Is it enough to just ensure good waterproofing? Thank you!
Should a separate drainage pump be installed? Is the drainage pump installed inside or outside the substation?
What are the disadvantages of using an aggregate pit in an indoor cable trench? Or are there any regulations that clearly specify which types of indoor cable trenches cannot be used as sump pits? Thank you!
There are no specific regulations requiring the creation of sump pits. In areas with high groundwater levels, I think it’s better to use sump pits. The main function of a sump is to facilitate pressure-driven drainage, that is, by placing a sewage pump in the sump to pump out water. The bottom of cable trenches is generally provided with a certain overhang, sloping toward the sump. This hardly increases the cost, and in the event that water enters the cable trench, it can be drained promptly and easily.
It is essential to have a sump pit; although the regulations do not require it, having one can be very effective in dealing with any potential water intrusion issues.
I’ve seen it; it’s in a switchgear room on the second floor – I’m not sure if that’s the correct term – a room where switchgear is kept. On the side by the window, there is another row of slats.
I’m the owner of a construction project; by checking the design specifications for 10KV substations, you should be able to find what you need, (GB50053-94)
Outdoor ditches should be constructed, and indoor ditches are advisable to facilitate drainage after water enters. Personal opinion.
After a risk analysis, if there is no possibility of rainwater backflow or leakage in the indoor cable trenches, it is not necessary to install sump pits. Drainage is absolutely essential to consider outdoors.
After a risk analysis, if there is no possibility of rainwater backflow or leakage in the indoor cable trenches, it is not necessary to install sump pits. Drainage is absolutely essential to consider outdoors.
Most electrical installations serve a preventive purpose, such as drains and sump pits. It is still recommended to carry out the work; otherwise, water will accumulate in the cable trench due to various reasons such as leakage or water needed for extinguishing fires, and this water cannot be drained, which affects the insulation of the equipment. Generally, the cable trench is led outside the building (with measures taken to prevent small animals from entering), and a sump pit is created outdoors. As long as the water in the trench is pumped below the level of the cable trench, the trench can be kept dry. In outdoor cable trenches, sump pits must be installed.