Electrical Room / Sub Switching Room Guidelines

July 13, 2023 2 Comments

 

IEC 61936-1
DOOR: Doors shall have a fire resistance of at least 60 minutes
Doors which open to the outside are adequate if they are of fire-retardant material and construction
Ventilation openings necessary for the operation of the transformers are permitted
When designing the openings, the possible escape of hot gases shall be considered
The doors of switchgear cubicles or bays should close in the direction of escape.
Length of Escape Route in Electrical Room Exits shall be arranged so that the length of the escape route within the room does not exceed 40 meter for installation of rated voltages Um greater than 52 kV, and 20 meter  for installation of rated voltages up to Um = 52 kV. This does not apply to accessible bus ducts or cable ducts
Permanently installed ladders or similar are permissible as emergency exits in escape routes.
No of Door If an operating aisle does not exceed 10 m, one exit is enough. An exit or emergency possibilities shall be provided at both ends of the escape route if its length exceeds 10 Meter
Service areas Service areas comprise aisles, access areas, handling passages and escape routes
Aisles and access areas shall be adequately dimensioned for carrying out work, operating switchgear and transporting equipment.
Aisles shall be at least 800 mm wide. The width of the aisles shall not be reduced even where equipment projects into the aisles, for example permanently installed operating mechanisms or switchgear trucks in isolated positions.
Space for evacuation shall always be at least 500 mm, even when removable parts or open doors, which are blocked in the direction of escape, intrude into the escape routes. For erection or service access ways behind closed installations (solid walls), a width of 500 mm is sufficient.
Windows Windows shall be designed so that entry is difficult. This requirement is considered fulfilled if one or more of the following measures are applied
The window is made of unbreakable material.
The window is screened
The lower edge of the window is at least 1.8 Meter above the access level
The building is surrounded by an external fence at least 1.8 Meter high.
External fences or walls and access doors Unauthorized access to outdoor installations shall be prevented. Where this is by means of external fences or walls, the height and construction of the fence/wall shall be adequate to deter climbing.
Height and construction of the fence/wall shall be adequate to deter climbing.
The external fence/wall shall be at least 1 800 mm high. The lower edge of a fence shall not be more than 50 mm from the ground.
Access doors to outdoor installations shall be equipped with security locks.
External fences/walls and access doors shall be marked with safety signs
Any adjacent fences, other structures and trees outside the installation should also deter climbing.

 

IS 3034: 1993
Cable Entry All cable entries in the switch gear room shall be effectively sealed by use of fire stops ( see IS 12459 : 1988 ).

 

Section 50A in The Indian Electricity Rules, 1956
FIRE BARRIER No other service pipes shall be taken along the ducts provided for laying power cables. All ducts provided for power cables and other services shall be provided with fire-barrier at each floor crossing

 

4.2-Substations and Switch Rooms (NATIONAL BUILDING CODE 2016)
   
At Basement Location of substation in the basement should be avoided, as far as possible.
Only One Basement In case there is only one  basement  in  a building, the substation/switch room shall not be provided in the basement.
Also, the floor level of the substation shall not be lowest point of the basement.
Central of Load Centre Ideal location for an electrical substation for a group of buildings will be at the electrical load Centre.
Generally  the  load  Centre will  be somewhere between the geometrical Centre and the  air  conditioning  plant  room,  as  air conditioning plant room will normally be the largest load, if the building(s) are centrally air conditioned.
Prevention of Strom Water / Water seepages In order to prevent storm water entering the transformer and switch rooms through the soak pits, the  floor  level  of  the  substation/ switch room shall be at least 300 mm above the highest  flood  water  level  that  may  be anticipated in the locality.
Also, facility shall be provided for automatic removal of water.
Not Above Water Tank / Sewage Plant Substation shall not be located immediately above or below plumbing water tanks or sewage treatment plant (STP) water tanks at the same location.
Sub Station Door All door openings from substation, electrical rooms, etc, should open outwards.
Vertical shutters (like fire rated rolling shutters) may also be acceptable provided they are combined with a single leaf door opening outwards for exit in case of emergency
For large substation room/electrical  room  having  multiple equipment,  two  or more  doors  shall  be provided which shall be remotely located from each other
More Distance between Transformer and HT Panel  In case of HV panel and Transformers located at different floors or at a distance more than 20 Meter, HV  isolator  shall  be  provided  at transformer end
More Distance between Transformer and MV/LV Panel In case transformer and main MV/LV panel room are located at different floors or are at a distance more than 20 Meter , MV/LV isolator shall be  provided  at  transformer  end. In  case transformer and main MV/LV panel room are located at different floors, the designer should

also take care of the safety requirements caused by lack of direct visibility of the status of the controlling switch. To cater to the safety requirements under different conditions of operation as well as maintenance, it may be

necessary to provide additional isolator or an emergency push button in the vicinity to trip the supply. Decision has to be taken based on the possible risks.
HT CABLE / HT Services The power supply HV cables voltage shall not be more than 12 kV and a separate dedicated and  fire  compartmented  shaft  should  be provided for carrying such high voltage cables to upper floors in a building. These shall not be mixed with any other shaft and suitable fire detection and suppression measures shall be provided throughout the length of the cable on each floor.
Horizontal  routing  of HT  cable  through  functional/occupied areas should be avoided in view of safety.
Wherever transformers are planned at higher floors, the HT cables shall be routed through a separate shaft having its own fire resistance rating of 120 min. Wherever HT generators are planned centrally at ground or first basement level, redundant transformers and HT cables shall be planned for buildings above 60 Meter in height.
No Shaft Opening in Sub Station Room No services or ventilation shafts shall open into substation or switch room unless specific to substation or switch room.
Derating Factor If substation is located at a height 1000 Meter above MSL,  then  adequate  derating  of equipment shall be considered.
Electrical Room The minimum height of the substation/HV switch room/MV switch room shall be arrived at considering 1200 mm clearance requirement from the top of the equipment to the below of the soffit of the beam.
For all buildings above 15 Meter in height and in special occupancies, like educational, assembly, institutional, industrial, storage, hazardous and mixed occupancies with any of the aforesaid occupancies having area more than 500 Sq. Meter on each floor, provision shall be made for an independent and ventilated meter (service) room, as  per  requirements  of  electric  (service)  supply undertakings on the ground floor with direct access from outside for the purpose of termination of electric supply from the licensees service and alternative supply cables. The door/doors provided for the service room shall have fire resistance of not less than two hours.
Cable Trench In case of cable trench in substation/HV switch room/MV switch room, the same shall be adequately drained to ensure no water is stagnated at any time with live cables
Power supply to emergency fire and life safety systems Emergency power  supplying distribution system for critical requirement for  functioning of fire and life safety system and equipment

(i) Fire pumps;

(ii) Pressurization and  smoke  venting systems including dampers and actuators

(iii) Fireman’s lifts (including all lifts).

(iv) Exit signage lighting;

(v) Emergency lighting;

(vi) Fire alarm system;

(vii) Public address (PA) system

(viii)Magnetic door hold open devices; and

(ix) Lighting in fire command Centre and security room.
Cables for fire alarm and PA system Cables for fire alarm and PA system shall be laid in metal conduits or armored to provide physical segregation from the power cables.
Stand By Supply (D.G Set) Diesel generator set(s) shall not be installed at any floor other than ground Floor or below first basement. In case of DG set located in basement, the ceiling of the DG room shall be the ground floor slab.

It is preferable If the same are installed indoors, proper ventilation and exhaust shall be  planned.  The DG  set  room  shall  be  separated by 120 min fire resistance rated walls and doors.
electrical supply, present at the time of fire. The height of diesel generating (DG) set rooms shall however be not more than 3 000 mm above the DG set height, unless required due to DG room ventilation requirements
The oil tank for the DG sets (if not in the base of the DG) shall be provided with a enclosure having a volumetric capacity of at least 10 percent more than the volume of the oil tank. The enclosure shall be filled with sand for a height of 300 mm.
Location of MV/LV Switch Room Other than in Substation provided, a separate switch room shall be provided this shall be located as close to the electrical load Centre as possible, on the ground floor or on the first basement level of the building.
Substation Safety Enclose any part of the substation which is open to the air, with a fence (earthed efficiently at both ends) or wall not less than 1800 mm (preferably not less than 2400 mm) in height to prevent, so far as is reasonably practicable, danger of electric  shock  or  unauthorized access;
Supply Company  High Voltage Meter Board (HTMC PANEL) Suitable isolating device fixed in a conspicuous position at not more than 1.7 m above the ground so as to completely isolate the supply to the building in case of emergency.
HV Cables When HV cable is hanging/running below the basement ceiling slab, the cable shall be laid in a fire rated enclosure/ cable tray.
Transformers The total installed transformer capacity shall be at least 15 to 20 percent higher than the anticipated maximum demand

 

Section 64 in The Indian Electricity Rules, 1956
Where It is necessary to locate the sub-station/switch station in the basement following measures shall be taken The room shall necessarily be in the first basement at the periphery of the basement.
The entrances to the room shall be provided with fire resisting doors of 2 hours fire rating. A curb (sill) of a suitable height shall be provided at the entrance in order to prevent the flow of oil from a ruptured transformer into other parts of the basement. Direct access to the transformer room shall be provided from outside.
The transformer shall be protected by an automatic high velocity water spray system or by carbon dioxide or BCF(Bromo chlorodi feuromethane)  or BTM (Bromo trifluro methane) fixed installation system
Oil filled transformers installed indoors shall not be on any floor above the ground or below the first basement.
A sub-station or a switch station with apparatus having more than 2000 liters of oil shall not be located in the basement where proper oil draining arrangement cannot be provided.

 

 

 

Filed under Uncategorized