General Requirements
Project Overview
• The forced ventilation system shall maintain acceptable temperature and air quality
levels in the MCC room, primarily by exhausting warm air and supplying fresh,
cooler air.
• The system must operate continuously (24/7) and ensure an optimal environment for
the operation of electrical equipment.
• Ventilation shall be sufficient to dissipate the heat load generated by the electrical
equipment.
Standards and Codes
• The design and installation of the ventilation system must comply with relevant local,
national, and international standards, including:
o ASHRAE 62.1 (Ventilation for Acceptable Indoor Air Quality)
o NFPA 70 (National Electrical Code)
o IEEE standards for electrical installations
o OSHA standards for workplace air quality
o Local Building Codes
Design Conditions
• External Ambient Temperature: Summer: 32°C and Winter: 22°C RH: 85%
• Room Internal Temperature: Maintain below 30°C (86°F), unless otherwise
specified by the equipment manufacturer.
• Heat Load:
• Electrical Classification: Non-hazardous environment
Ventilation System Design
Ventilation Capacity
• The ventilation system shall have sufficient airflow capacity to remove the total heat
load generated within the MCC room.
• The required airflow rate to maintain the room at 25°C should be at ___
Supply Fan
• The system shall include an appropriately sized fresh air supply fan to provide
continuous air exchange.
• Fans shall be equipped with speed control to adjust airflow based on room
temperature (e.g., using a thermostat).
• Noise level of the fan should not exceed 65 dBA to ensure a comfortable working
environment for personnel and attenuators should be selected to reduce the fan noise.
Air Distribution and Balancing
• A fresh air fan to be installed at high level with weather louvre (--mm x –mm) and
primary filter.
• Airflow should be directed towards heat-producing equipment (MCC panels,
transformers, etc.) to ensure efficient cooling.
• Exhaust air shall be pushed out via louvres from the upper parts of the room, where
hot air will accumulate.
• The system shall be balanced to ensure that hot spots are avoided, and adequate air
movement is maintained throughout the entire room.
Air Changes per Hour (ACH)
• The system shall provide a minimum of 6 air changes per hour (ACH). Higher ACH
may be necessary depending on the heat load.
Filters and Grilles
• Air intake grilles shall be equipped with filters (minimum MERV-8 rating) to
prevent dust and debris from entering the room.
• Exhaust grilles shall be located to maximize the removal of hot air and ensure proper
airflow through the room.
Pressurization
• The room should be slightly pressurized to prevent the ingress of dust and
contaminants. This can be achieved by supplying slightly more air than is being
exhausted (positive pressure ventilation).
3. Equipment Specifications
3.1 Fans
• Type: Centrifugal or axial fans with adequate capacity for the calculated airflow.
• Fans shall be rated for continuous duty and shall have a minimum efficiency of 70%.
• Motor power: Sized based on the fan selection and airflow requirements.
• Speed control: Variable speed drives (VSD) or controllers shall be included to adjust
fan speed based on real-time temperature.
3.2 Temperature Control
• A thermostatic control system shall be provided to monitor room temperature and
adjust fan speed accordingly.
• Temperature sensors should be placed near the MCC panels and at other strategic
points in the room.
• The control system shall include high-temperature alarms to alert operators if the
room temperature exceeds safe levels.
3.3 Exhaust and Intake Louvres
• Louvres shall be installed at the air intake and exhaust points to prevent rain, insects,
or debris from entering the ventilation system.
• Louvres should be adjustable to control airflow, and they should automatically close
when the system is not in operation.
4. Electrical and Safety Considerations
4.1 Power Supply
• The ventilation system shall be powered from a dedicated electrical circuit. In critical
facilities, it should be connected to an uninterruptible power source (UPS) or
emergency generator.
4.2 Fire and Smoke Protection
• Fire dampers shall be installed in all ducts passing through fire-rated walls or
ceilings.
• The ventilation system shall automatically shut down in the event of fire detection via
the room’s smoke detection system.
4.3 Explosion Proofing (if required)
• If the MCC room contains hazardous areas or equipment, fans and electrical
components shall be explosion-proof and meet appropriate classification standards
(e.g., Class I, Div 2 or ATEX).
1 5. Commissioning and Testing
5.1 System Testing
• The ventilation system shall be tested for airflow, temperature control, and proper
operation under typical and maximum heat load conditions.
• Balancing of the system shall be verified to ensure uniform airflow throughout the
MCC room.
5.2 Documentation
• Provide as-built drawings, operation manuals, and maintenance schedules for all
ventilation components.
• Training shall be provided for facility staff on system operation, controls, and
troubleshooting.
