What is the specific content of the discussion on the electrical design of sauna facilities? Zhongda Consulting will answer it for you below.
Discussion on the electrical design of sauna places_Bisen Youxin_Architectural Design_Architecture Chinese Network Sauna is a special place, and there are special electrical safety issues that are different from general places. The International Electrotechnical Commission (IEC) ) has formulated a special standard for this - IEC60364-7. The author wants to deepen the understanding of the IEC clauses and the relevant provisions of my country's electrical regulations by analyzing and sorting out the decoration project examples of a hotel's underground sauna city. Any inappropriate points are still hoped for. Peers are willing to correct me.
1. Strong current system
1.1 Power distribution system
The grounding system of the low-voltage distribution system of this project is TN-S, and the main distribution box is in the strong current The shaft is exposed and the power supply is led from the low-voltage power distribution room of the building using low-smoke and halogen-free five-core cross-linked power cables.
Article 4.4.3 of "Low Voltage Distribution Design Specification GB50054-95" stipulates that "the environment where the equipment is located is a normal environment, and the safety voltage limit for personal electric shock (UL) is 50V." In a humid environment, the contact voltage that causes ventricular fibrillation is much lower than 50V. In order to prevent electric shock accidents caused by potential introduced from outside the site, local equipotential bonding must be done. Therefore, the bathrooms, dry steam rooms, wet steam rooms, and pools (including hot pools and cold pools) in this project should all be equipped with equal potential connections by referring to pages 16 and 17 of the national standard atlas "Equipotential Bonding Installation 02D501-2" .
It should be noted that if there are no PE lines and Class I equipment in the area (such as the pool in this project, which only has 12V pool lights), do not introduce PE lines from outside the area to avoid self-defeating and introducing fault voltage. , but increases the risk of electric shock. In this project, the pool is not cast in place, and there is no steel mesh at the bottom of the pool, so potential equalization wires should be laid, using ф3 iron wire to form a 150mmX150mm grid.
Because there are many power equipment in the sauna, the environment is humid, and the normal leakage current of electrical equipment is large, so the incoming circuit breaker of the main distribution box does not use a leakage circuit breaker, but only the lighting of its outlet circuit Leakage circuit breakers are installed on the box power distribution circuit, dry steam room, and wet steam room power distribution circuits. The lighting distribution box circuit is equipped with a fire-proof leakage circuit breaker, and the leakage action current value is set to 300mA, with a specified delay, which can effectively remove arc ground faults; the dry steam room and wet steam room power distribution circuits are set with a leakage action current of The 30mA instantaneous and fast-acting leakage circuit breaker can quickly remove metallic ground faults. Doing so can not only avoid frequent tripping of the incoming circuit breaker, reduce the scope of power outages, reduce people's panic, but also effectively prevent electrical fires and protect personal safety. Judging from the operation over the past year, this design idea was correct.
1.2 Lighting system
1.2.1 Normal lighting
The stairwell, elevator front room, parking aisle, service desk, and rest hall of this project , VIP rooms, massage rooms and other places use three-color energy-saving downlights, and the lines are all made of flame-retardant polyvinyl chloride insulated wires and laid in steel pipes in the ceiling (ACC).
The pool light uses 12V safety extra-low voltage and is powered by a step-down isolation transformer. It should be noted that the 220V/12V transformer should be installed in a dry place, and the secondary circuit wire of the isolation transformer and the lamp shell are not grounded. When a wire collision failure occurs, there is no potential difference between the shell and the ground. In order to avoid introducing fault voltage, the lines cannot use metal pipes, but should be laid through hard plastic pipes. The protection level of the pool lamp is IPX8.
The top lighting of the pool area uses waterproof energy-saving downlights, and the protection level is IPX4. The lines are all made of flame-retardant polyvinyl chloride insulated wires and are laid through steel pipes in the ceiling (ACC).
Dry steam rooms and wet steam rooms are places of high temperature and humidity, so their electrical safety requirements are mainly to prevent electrical insulation from being harmed by high temperatures. According to IEC regulations, Zone 4 of the sauna is the area between the horizontal plane 0.3m away from the roof and the roof, which is a space where high-temperature air is concentrated. The lighting fixtures are waterproof energy-saving downlights with a protection level of IPX5. The lighting circuits are double insulated, and heat-resistant polyvinyl chloride insulated wires are used to pass through hard plastic tubes and laid in the ceiling to avoid reducing the insulation level of the circuits due to high temperature and humidity.
However, it should be noted that the rigid plastic pipe must be flame-retardant and its oxygen index should be at least 27% to meet the requirements of Article 5.2.12 of the "Low Voltage Distribution Design Code GB50054-95" and the "Electrical Design of Civil Buildings" Comply with the requirements of Article 9.5.1 of Specification JGJ/T16-92.
There is a controversial issue here. Article 5.2.7 of the "Low Voltage Distribution Design Code GB50054-95" stipulates that "metal tubes and metal trunking must be used for wiring in the ceiling of the building." Article 5.2.1 of the Electrical Volume of the "National Civil Construction Engineering Design Technical Measures" released in 2003 also stipulates that "metal tubes and metal trunking should be used for wiring in the ceiling of the building." Article 9.5.1 of the "Electrical Design Code for Civil Buildings JGJ/T16-92" stipulates that "in the ceiling of the building, flame-retardant rigid plastic pipes can be used for wiring." It can be seen that there are differences between domestic electrical design specifications and between domestic electrical design specifications and IEC standards. The author believes that the standards for special places or devices formulated by IEC just make up for the shortcomings of my country's electrical standards in this regard, so national standards cannot be blindly copied in design. The electrical design of special places such as saunas must comply with IEC standards and fully reflect the "people-oriented" principle. Therefore, the author agrees with the use of flame-retardant hard plastic pipe wiring in saunas instead of metal pipe wiring.
1.2.2 Emergency lighting
According to the provisions of Articles 10.2.6 and 10.2.8 of the "Code for Fire Protection Design of Buildings GBJ16-87" (2001 Partially Revised Edition), this The project is equipped with fire accident lighting in the front room of the closed stairwell, elevator front room, evacuation aisle, rest hall and pool area; luminous evacuation indication signs are set up in the evacuation aisles and main evacuation routes. The distance between aisle indication signs shall not be greater than 20m. According to " Article 24.8.5 of the Electrical Design Code for Civil Buildings JGJ/T16-92, the above lines must be protected by metal pipes.
The fire accident lighting and evacuation indicator lights in this project have a small capacity and are relatively scattered. Therefore, the centralized emergency power supply was not considered during the design, and the battery in the light was used as a backup power supply. Article 10.1.2 of the "Code for Fire Protection Design of Buildings GBJ16-87" (2001 Partially Revised Edition) stipulates that the continuous power supply time should be no less than 20 minutes in this case. This provision (a mandatory provision) is consistent with the norm "Fire Emergency Lamps GB17945" -2000》is a far cry from the 90 minutes required. It is not uncommon for my country's current electrical design specifications to conflict with each other. The author believes that wherever the specifications conflict with each other, they should be implemented according to the provisions with high requirements and strong professionalism. Therefore, the author did not copy the mandatory provision "emergency time 20 minutes" in the construction drawings, but marked "emergency time 90 minutes" and implemented it according to a higher standard.
1.3 Power Distribution
IEC stipulates that the sauna room is divided into Zone 1 within a vertical plane 0.5m away from the edge of the heater and the height ends at 0.3m away from the ceiling. Within this area No extraneous equipment and wiring should be installed except for the heater itself. Therefore, the heater circuit uses heat-resistant polyvinyl chloride insulated wires, which are passed through hard plastic pipes and laid concealed along the ground, and are also double-insulated. Since both the dry steam room and the wet steam room use complete sets of equipment, this part of the power distribution only needs to lay the power pipelines in place and embed the junction box on site. Equipment capacity shall be based on the equipment list provided by Party A.
The sewage pump, bath massage pump, water treatment circulation pump, dosing pump and other power equipment of this project are all installed in a dedicated equipment room and are controlled centrally by two customized electric control boxes. The door is equipped with control buttons and operation indicator lights. The sewage pump has one use and one standby, and the liquid level is automatically controlled. Its secondary circuit adopts the standard control circuit diagram according to the national standard design atlas "Common Water Pump Control Circuit Diagram 01D303-3".
The building uses centralized air conditioning, and the underground sauna city is integrated into the original air conditioning system. The terminal equipment is a fan coil unit, which serves as temperature regulation for independent rooms. The temperature controller - some people call it a "speed control switch" is inaccurate - is located near the door of each room or in an easily accessible location, and is placed at the same height as the room's light switch. Note that there are five wires between the thermostat and the fan coil junction box, and the plan view should be clear. The author found that the four lines marked on some design institute drawings are incorrect. Looking through the manufacturer's product samples, we can see that fan coil units are all single-phase equipment, with low power of only tens of watts and high power of only about 200 watts.
Therefore, several fan coil units in the design can completely use one power supply circuit. There is no need to set up an independent distribution box for the fan coil unit. It is enough to use several independent outlet circuits of the lighting distribution box. This is also a common practice among people in the industry.
Coordination and communication between majors should also be strengthened in the design. The electrical major should work closely with the HVAC major to jointly determine the locations of air outlets, fan coils and lamps to avoid each major doing its own thing. , resulting in construction difficulties and visual failure in decoration.
2. Weak current system
2.1 Automatic fire alarm system
In accordance with the "Building Design Fire Protection Code GBJ16-87" (partially revised in 2001) Section 10.3.1B According to the regulations, the underground sauna city must be equipped with an automatic fire alarm system. Since the building has a fire control room, it is only necessary to set up a fire wiring terminal box in the weak current shaft on this floor, through which the fire alarm circuit and linkage control circuit can be integrated into the original system. The design only needs to strictly abide by the relevant provisions of the "Design Specification for Automatic Fire Alarm Systems GB50116-98". However, it should be noted that the model specifications of the fire alarm system components should be consistent with the original system.
2.2 Cable TV system
This project will set up cable TV outlets in the VIP rooms and lounges. Each VIP room is equipped with an outlet, which is positioned according to the building decoration drawings and installed 0.3m away from the ground. The leisure hall is equipped with two outlets, which are installed on poles 1.3m above the ground. This is because if the installation height is low, customers will not have a good view; if the installation height is too high (if the TV is hoisted in some places), over time, customers will suffer from neck fatigue due to the excessive elevation angle. Engineering design should take these human aspects into account.
2.3 Communication system
The communication system of this project is functionally divided into two parts: internal call system and local telephone system. An internal call system is set up between the VIP room, massage room and main service desk to respond to customer requests in a timely manner. In order to reduce the project cost, mature call system products (such as Hongyan Electric's DX-128 series) were not used in the design. Instead, the expansion slot of the program-controlled switch in the building was fully utilized to expand the capacity of the switch and use the switch to complete internal communications, which reduced the cost of the project. Project cost. As for local calls, only two direct-dial telephones need to be installed at the main station to communicate with external parties.
2.4 Closed-circuit television monitoring system
In order to protect people's personal and property safety, this project has set up a closed-circuit television monitoring system to monitor key parts. Install fixed cameras on evacuation stairs, elevator front rooms, walkways, and service desks, and install dome cameras in the leisure hall. Major equipment such as monitors, embedded hard disk video recorders, matrix controllers, and control hosts are all set up at the main service desk.
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