Layout of Power Distribution and Control Lines for Smoke Exhaust Fans in Commercial Buildings

Youtube:https://youtu.be/nX755jugC94

The layout of power distribution and control lines for smoke exhaust fans in commercial buildings needs to comply with 

relevant electrical codes and fire protection requirements. The following are the specific layout key points:

### Layout of Power Distribution Lines

- **Line Selection**: Wires and cables with good fire resistance performance should be selected, such as NH-YJV

 (Fire-resistant Cross-linked Polyethylene Insulated Polyvinyl Chloride Sheathed Power Cable), etc., to ensure that 

normal power supply can be maintained for a certain period of time in case of a fire. Calculate the required cable 

cross-sectional area according to the power and voltage level of the smoke exhaust fan to ensure that the cable 

can carry the rated current of the fan. At the same time, a certain margin should be considered to deal with possible

 overload situations.

- **Laying Methods**

    - **Exposed Laying**: When protected by metal conduits or metal trunking, fire protection measures should be

 taken on the metal conduits or metal trunking, such as applying fireproof paint.

    - **Concealed Laying**: It is advisable to lay it concealed through rigid conduits within a non-combustible

 structure, and the thickness of the protective layer should not be less than 30mm. This can effectively prevent

 the cable from being damaged by fire and improve the reliability of power supply.

- **Setting of Power Distribution Box**: A dedicated power distribution box should be set up to supply power to 

the smoke exhaust fan. The power distribution box should be installed close to the smoke exhaust fan and be easy

 to operate and maintain. Protective devices such as short-circuit, overload, and grounding should be set up in the

 power distribution box to ensure the safe operation of the power distribution system. At the same time, the shell 

of the power distribution box should be made of fireproof and moisture-proof materials.

- **Power Supply Introduction**: The power supply of the smoke exhaust fan should be introduced from the fire

 power supply distribution box of the building to ensure reliable power supply during a fire. The fire power supply

 should have an independent power supply circuit and be set separately from other non-fire power supplies to

 ensure the priority power supply of fire-fighting equipment in case of an emergency.

### Layout of Control Lines

- **Control Modes**: Smoke exhaust fans generally adopt three control modes: on-site manual control, remote 

control from the fire control room, and automatic control. The on-site manual control button should be installed 

at a position near the smoke exhaust fan that is easy to operate and should have obvious identification. The remote

 control from the fire control room is realized through the automatic fire alarm system, and the stable and reliable

 transmission of control signals should be ensured. Automatic control starts the smoke exhaust fan automatically 

according to the signals of the fire detectors.

- **Line Laying**: The control lines should be laid separately from the power distribution lines to avoid mutual

 interference. Generally, it is laid through metal conduits or metal trunking, and fire protection measures should 

also be taken. The control lines should try to avoid parallel laying with other high-voltage power lines. If parallel 

laying is required, a certain safe distance should be maintained to prevent electromagnetic interference.

- **Signal Feedback**: A signal feedback device should be installed on the smoke exhaust fan to feedback the 

operation status of the fan (such as running, stopped, faulty, etc.) to the fire control room. The feedback signal 

lines should also use reliable wires and cables and be laid together with the control lines to ensure the accurate 

transmission of signals.

- **Grounding Protection**: The metal conduits, metal trunking, power distribution boxes, etc. of the power 

distribution and control lines of the smoke exhaust fan should all be reliably grounded, and the grounding

 resistance should meet the requirements of relevant specifications. The grounding system should adopt the 

TN-S system, that is, the three-phase five-wire system, to ensure the safe operation of electrical equipment and

 the safety of personnel.

### Other Precautions

- **Neat and Aesthetic Wiring**: The power distribution and control lines should be arranged neatly and orderly 

during the layout to avoid being messy. The cable trays or trunking should be installed firmly, horizontally and 

vertically. The cables should be arranged neatly in the trays or trunking and fixed with cable ties or wire clips.

- **Reserve Maintenance Space**: When laying the lines, the needs of future maintenance and repair should be 

considered. Sufficient space should be reserved at the cable joints, power distribution boxes, and other parts to 

facilitate the operation of maintenance personnel.

- **Clear Identification**: Clear identification plates should be set up at the starting points, ending points, branch

 points, etc. of the power distribution lines and control lines, indicating information such as the purpose and 

destination of the lines to facilitate daily maintenance and troubleshooting.