Power supply and distribution design standards and code requirements for hotel fire elevators

Power supply and distribution design standards and code requirements for hotel fire elevators

I am electrical expert James Li, specializing in electrical system design and code application. The hotel fire elevator power supply and distribution design issue you raised is a core part of building electrical safety and directly relates to the reliability of occupant evacuation and fire rescue during a fire. According to the Code for Fire Protection Design of Buildings GB 50016-2014 (2018 Edition) and the Code for Design of Power Supply and Distribution Systems GB 50052-2009, fire elevators, as particularly important loads within Class I loads, must have power supply and distribution designs that meet the highest level of reliability requirements. The following provides a detailed analysis of design standards and code requirements based on code clauses and engineering experience.

Design Standards and Code Requirements

• According to Article 10.1.8 of GB 50016, the power supply for fire elevators shall be provided with an automatic transfer device at the final distribution box, and shall meet the power supply requirements for Class I loads. According to Article 3.0.1 of GB 50052, Class I loads shall be supplied by two independent power sources, and particularly important loads (such as fire elevators) also require an additional emergency power source (such as a diesel generator or UPS).
• Engineering Experience: In hotel projects, I often adopt a design using dual power sources (such as utility power + standby generator) coordinated with a terminal dual-power transfer box (ATSE). For example, in a certain five-star hotel, the fire elevator was supplied by two independent 10 kV power sources from the substation; after voltage reduction through transformers, a dual-power transfer box was installed in the fire elevator machine room, with a transfer time not exceeding 15 seconds, ensuring that the power supply would not be interrupted during a fire.

• According to Article 10.1.10 of GB 50016, fire protection distribution lines shall use mineral-insulated cables (such as BTTZ or YTTW) or flame-retardant fire-resistant cables, and shall be laid in dedicated cable trays or protected by metal conduits. Overload protection of the lines shall only actuate an alarm and shall not cut off the power supply (Article 6.3.4 of GB 50054).
• Actual Case: In a renovation project, the original design used ordinary cables, which did not comply with the code. I recommended replacing them with WDZN-YJY (low-smoke halogen-free flame-retardant fire-resistant cables), laid separately in fire-rated cable trays, with fireproof coating applied to the outside of the trays. During acceptance, fire resistance testing was passed, ensuring that the lines could maintain power supply for more than 180 minutes during a fire.

• The distribution box for fire elevators shall be provided independently and marked with the words "Fire Equipment" (Article 10.1.9 of GB 50016). The control box shall have automatic fire alarm linkage functionality, automatically homing the elevator to the ground floor and opening the doors during a fire (according to Article 4.7.1 of the Code for Design of Automatic Fire Alarm Systems GB 50116-2013).
• Engineering Experience: In hotel design, I require that the fire elevator distribution box be separate from the ordinary elevator distribution box and installed in a dedicated electrical shaft. For example, in a certain project, due to space constraints, the fire elevator distribution box and the ordinary elevator shared a shaft; I insisted on adding a fire partition to ensure a fire resistance rating of not less than 1 hour. During linkage testing, through the fire alarm signal, the elevator successfully homed within 60 seconds.

• According to Article 5.2.4 of GB 50054, the metal enclosure, guide rails, distribution boxes, etc. of fire elevators must be reliably grounded and connected to the main equipotential bonding (MEB) system. The grounding resistance shall be less than 1 ohm (Article 4.2.1 of GB 50057).
• Actual Case: In a certain hotel in the north, due to high soil resistivity, the measured grounding resistance reached 4 ohms. I recommended increasing the number of grounding electrodes and using resistance-reducing agent, ultimately reducing it to 0.8 ohms, meeting the code requirements. At the same time, local equipotential bonding (LEB) was provided in the elevator machine room to prevent electric shock risks caused by potential differences.

Concluding Summary