• Document No.

  • Transportable Switch Room Checklist


  • Time

  • Inspection Type

  • Basic Location

  • Specific Location/s
  • Attendees

2.1 General Building Design

2.1 General Building Design

  • The switchrooms shall be designed to be fully transportable structures, either in one piece or in a multi-part modular form. The maximum allowable outside dimensions for any transportable switchroom or part thereof shall be 6500 mm wide, 4000 mm high and 25000 mm long unless otherwise specified or approved by the Company Representative.

  • The switchrooms shall be designed and constructed to meet the requirements of this specification, the local switchroom codes and regulations and fire service regulations. All nomenclature, definitions and ratings shall be in accordance with the relevant standards where applicable.

  • Any departures from the specified requirements shall be submitted for approval to the Company Representative prior to commencing any design, fabrication or construction. Such approvals shall only be provided after due consideration of any conflict with the standards, codes and good design practice.

  • Standard replacement parts for all components shall be readily available in the event of damage or wear. All materials of construction shall be non-combustible.

  • Where switchrooms are designated as being transported in parts, they shall be modularised for ease of separation for transport and rejoining on site. The roof and walls shall include sufficient flashing on site to produce a weatherproof and dustproof room once sections have been rejoined.

  • Switchrooms being transported in sections shall be designed for the expected lifting, transport and in service loads in accordance with the design intent. Remounted switchrooms on site shall be connected structurally. The switchrooms shall be temporarily braced and made weatherproof as necessary during transport and site erection.

  • All equipment housed within the switchrooms shall be installed in their final position before the switchrooms are delivered to site. The switchrooms, including all equipment, structural systems, finishes and materials shall be designed and constructed to withstand all loads imposed during lifting, transport and erection and operation over 25 years in a highly corrosive environment.

  • The design shall ensure that the site labour content associated with the final installation, testing and commissioning of the switchrooms is minimised to essential activities such as lifting, coupling and flashing of modules, connection of services, installation of equipment removed for transport, final testing, commissioning and similar.

  • Switchroom buildings shall be divided into separate rooms as detailed on the layout drawings. HV and LV shall be housed in separate rooms, and where nominated communications rooms shall be separate from LV or HV rooms.

  • Room sizes shall suit the size and nature of the equipment being housed, yet minimum sizes may be specified in the Contract Documentation.

  • Switchrooms shall be provided with sufficient space for future extensions of the switchgear and switchboards. Unless otherwise specified in the Contract Documentation, a minimum future spare space allowance for an extra full tier at each end of switchgear and switchboards shall be made.

Switchrooms shall be sealed to prevent the ingress of dust, vermin and insects, minimum IP55 (except for dedicated fan and air conditioner installations approved by the Company Representative). The buildings shall be designed and constructed to maintain their protection rating and construction integrity with minimal consequential damage to fitted equipment under the following typical conditions:

  •  Site conditions as specified in the Scope of Work

  •  Rough road transported by truck

  •  Ocean transport on the deck of a container ship

  •  Loads due to loading and unloading at ship wharves, with similar treatment as would be given to a standard shipping container.

Measures to prevent ingress of dust shall include, but not be limited to:

  •  Sealing of all roof, wall and floor spaces to prevent dust migration to internal spaces

  •  Use of air locks for all personnel entry points if specified

  •  Approved seals to all external doors and other openings

The Contractor shall pay particular attention to and develop appropriate solutions for:

  •  Low maintenance

  •  Minimising heat loads into switchrooms

  •  Minimising electrical operating load/costs

  • If specified in the Scope of Work, the Contractor shall fit out the switchrooms with free issued equipment. The free issued equipment shall be delivered free on transport to the Contractor’s site; the Contractor shall be responsible for unloading, safe keeping, and storage of the equipment. The Contractor shall supply and install the cable gland plates complete with glands, cable ladders and any cable supports for all the free issued equipment.

  • The Contractor shall supply and install all interconnecting cables between the equipment installed within the switchroom. The Contractor shall be issued with cable schedules detailing those cables considered part of the switchroom design scope. Generally this is considered to be all cables running from one location within the switchroom to another location within the same or immediately adjacent switchroom, and excludes field cabling.

  • The Contractor shall run all control and communications cabling between switchroom equipment in overhead cable ladder, and all power cabling between switchroom equipment in cable ladder below the floor within the base frame cavity. The Contractor shall ensure that the cable ladder within the base frame cavity is suitably mounted and protected such that it does not require removal during transport to site.

  • Where buildings are split into transport sections, a suitable, approved method shall be employed to allow the reconnection of the cabling and/or building wiring on site in the shortest time possible.

  • Cable support, ladder and gland plates shall be designed to suit all interconnecting cables within the switchroom and field cabling. The Contractor shall submit detailed design drawings of the cable support systems and gland plates for review.

  • The Contractor shall test and pre-commission all electrical equipment and interconnecting cables. The scope of testing and pre-commissioning shall be detailed in the Contractor's inspection and testing procedures.

2.2 Construction

2.2 Construction

  • The building construction integrity is vital to the long term operations on site. Sandwich-panel type construction is not acceptable.

The general construction of prefabricated, transportable type, switchrooms shall be:

  •  Heavy duty, structural steel framed construction

  •  Steel fabricated fully welded base frame, walls, floor and roof

  •  Unless otherwise specified, prefabricated switchroom buildings shall be designed as elevated buildings

  •  Unless otherwise specified prefabricated switchroom buildings shall be supplied complete with all support footings, landings and stairs

  •  Except where approved otherwise, switchroom buildings shall be designed for cable entry into switchboards from below, and sufficient switchroom internal height for cable ladder above the switchgear.

  • Alternative methods of construction may be approved for certain low risk installations which cannot cause serious loss in the event of equipment damage. Approval shall be given by the Company Representative.

  • All materials used shall be new.

2.2.1 Walls

  • Walls shall be constructed from minimum 75 mm galvanised welded frames, insulated with non-combustible thermal insulation and sarked to achieve the specified insulation R-values.

  • Wall and ceiling panels shall feature exterior and interior metal skins. Metal skins shall be manufactured from Colorbond® steel at least 0.5 mm thick and fixed at centres no less than 200 mm apart. All metal skin exterior and interior wall and ceiling cladding shall be earthed.

  • The type of external cladding, Colorbond® Standard, Ultra or Stainless ranges, shall suit the corrosive nature of the environment into which the switchroom shall be installed.

The exterior colours shall be:

  •  Sides Colorbond® Pale Eucalypt

  •  Roof Colorbond® Dune

  •  Trim Colorbond® Cottage Green

  • Internal cladding shall be of the Lysaght Panelrib® or approved similar light panel rib type, minimum 0.4mm thick, and installed as per manufacturer’s recommendations, with the ribbing running vertically to avoid dust accumulation. Horizontal ribbing shall not be used in any location. The switchroom Contractor shall provide a method of sealing and fixing the sheet overlaps so that pressurisation loss is eliminated. All openings in the switchroom panelling shall be made vermin, insect and dust proof. Each switchroom building, whether it contains a gas suppression system or not, shall be suitably sealed at the time of the FAT testing, such that it shall pass a Fan Integrity Test in accordance with AS 4212.

The interior colours shall be

  •  Sides Colorbond® Surfmist

  •  Ceiling Colorbond® Surfmist

  • Walls nominated as fire rated on the switchroom drawing layouts shall be designed and fabricated to include a certified minimum FRL120/120/120 fire rated barrier. Walls that are directly adjacent to transformer compounds, plus five (5) metres on each side of this shall be fire rated. There shall be no openings or penetrations through the walls nominated as fire rated. Furthermore, the extent of the fire rated walls shall be identified with signage that includes the words “FIRE RATED WALL DO NOT PENETRATE” or equal approved.

  • Equipment mounted on interior or exterior walls shall be rigidly supported from a structural member of the switchroom. Wall panels shall not be used for mounting equipment. Unistrut (or equivalent) shall be used for mounting of equipment on the walls and shall be rated to hold the weight of the equipment nominated plus 50% additional weight.

  • Equipment that is to be wall mounted shall have a centre of gravity that is 200mm off the wall and 1500mm above the floor. All wall-mounted equipment shall be installed with cable ladder running from the underside of the equipment to the floor. Cable ladder covers secured to the cable ladder for the entire run length shall be provided for mechanical protection of the cables.

2.2.2 Roof and Ceilings

  • The roof framing shall be of steel construction and the cladding shall be installed to match that of the walls.

  • The roof shall be a raft style platform with galvanised sections used as perimeter members and joists. The roof shall be sloped away from the high voltage side of the building. All laps and seams in the roofing shall be sealed using appropriate flexible sealant.

At ridges and eaves, the ends shall be treated as follows:

  •  Provide pre-cut notched eaves flashing and bird-proofing where necessary

  •  Project sheets 50mm into location of gutters

  •  Provide purpose-made ridge fillers of closed cell polyethylene

  •  Close off ribs at bottom of sheets by mechanical means or by purpose-made fillers or end caps

  •  Finish off along ridge and verge lines with purpose-made ridge capping or barge rolls

  •  Where end laps are unavoidable, and the sheet profile is not suitable for interlocking or contact end laps, construct a stepped type lap as recommended by the panel manufacturer.

  • Cornices and flashing shall be finished in the identical material as that of the external wall cladding and match both the colour and profile of the cladding. Gaps between the sheeting and flashing shall be sealed to prevent the loss of building pressurisation.

  • A rain canopy shall be installed for the full extent over each landing entrance door. The canopy and its final installation, shall fully comply with operation under the site conditions. It shall thus be suitably strong in design, to withstand the maximum site weather conditions at each switchroom location. The canopy shall be removed for transport to site.

  • Gutters, downpipes and flashing shall be manufactured from the same material as the cladding or approved equivalent.

  • Gutters and down pipes shall be provided on both sides of the switchroom with provision for down pipes at both ends of the switchroom. The down pipes are to extend to 200mm above AFFL of the ground below.

  • Prior to transport the down pipes shall be removed, and packed for transport to site where they shall be re-attached.

  • All ceilings and / or roof systems shall be provided with non-combustible thermal blanket insulation and fire retardant sarking to a minimum R-value required by the Contractor to meet the air conditioning design requirements. The Contractor shall recommend suitable alternatives for approval by the Company Representative.

2.2.3 Switchroom Base

  • The substructure of each switchroom shall be designed as a complete structural system including main base frame members, floor joists, and equipment landings, supporting columns, bracing systems, support footings, landings and stairs.

  • The base of the switchroom building shall have a perimeter frame constructed on parallel flange channel members with floor joists spaced no more than 1000 mm apart. The base frame and floor joists shall be an all-welded steel construction manufactured in accordance with the referenced standards. The base frame members and floor joists shall be arranged such that they maintain clear openings for cable entry points.

  • The base frame and substructures shall be designed for the switchroom equipment weight plus a minimum floor live load of 10 kPa within the switchroom and cable ladder system load of 5 kPa supported under the base frame. It is intended to support the cable ladder system from a varying combination of the support footings, base frame and from the ground below, depending on the location and composition of the switchroom.

  • The switchroom Contractor shall design and supply lifting lugs to allow lifting of the transportable switchrooms fully fitted out with all electrical equipment. The lifting lugs shall be removable.

  • The building dead load weight, including all installed equipment shall be provided to the Company Representative. The switchroom Contractor shall design, document and provide a lifting study and plan for each transportable switchroom, including dimensioned details of the estimated centre of gravity point of the switchroom. This point shall be marked on the building.

  • The steel support frame for the building, including the ceiling supports, shall be effectively earthed to the base frame.

  • A 2mm x 50mm galvanised threaded steel stud shall be welded to each end of the base support structure for site earthing. The studs shall be fitted with two galvanised flat and one galvanised spring washer and two galvanised nuts.

  • The base frame shall be hot dipped galvanised or specially painted following an approved system to ensure longevity and a durable finish, refer Section 2.2.7.

2.2.4 Flooring

  • The flooring shall be manufactured from compressed fibre cement (CFC) sheet with a minimum thickness of 18mm. Fixings shall be countersunk, filled and sanded smooth.

  • A fire resistant material shall be installed between the structural members and the CFC for added fire protection

  • The maximum permissible floor deflection during equipment fit-out, lifting and transportation shall be 1mm in 1000mm in all directions.

  • Cable openings for future switchgear and switchboards shall have removable panels fitted. The panels shall be made from the same material as the flooring and covered with the same coating material as the floor. The panels shall be fixed in place with countersunk screws. If required galvanised support brackets shall be fitted into the opening to carry the panels. If support brackets are used they shall be designed to support 500 kg of weight.

  • Alternatively, 4mm aluminium checker plate may be used to fill the cut-outs. The top of the checker plate shall be level with the top of the floor.

  • Floor covering shall be industrial, heavy duty type, minimum slip group R9 (according to AS/NZS 4586), antistatic, minimum 2.5mm, Vinyl Sheet floor covering reinforced with a polyurethane finish. The floor covering shall be installed once all floor-mounted equipment has been fixed within the switchroom and before transport to site. All joins in the vinyl sheets shall be butt welded with no gaps and the edges butted-up against plinths of floor-mounted equipment in a neat tradesman-like fashion. The vinyl shall wrap up the walls by 100 mm to provide an additional dust seal between the wall and the floor.

  • Once the floor covering has been completed, inspected and accepted as ready for transport, the Contractor shall install temporary, yet durable disposable floor protection over the floor covering to protect it from damage during construction.

2.2.5 Internal Floor Spacing - The following criteria shall be used to minimise the floor area design of each switchroom:

  •  The minimum distance between non-withdrawable parts and any obstruction, including lifting handles, shall be 600mm

  •  The minimum distance between a withdrawable or hinged part and any obstruction shall be 600mm in any direction after the part is fully withdrawn or open at 90º

  •  At each end of a switchboard or MCC there shall be sufficient floor space to install at least one further switchgear unit or tier (including cable zone) plus a minimum of 1000mm clear access

  •  Switchrooms for HV switchgear which require separate earthing trucks shall include parking space for the storage of the earthing trucks. The parking bay shall not be in the emergency escape route

  •  The floor area shall include space for a desk with chair, battery charger and batteries, UPS unit, wall mounted steel storage cupboard for storage of small components and the storage of switchgear operating tools

  •  Sufficient space shall be allowed for distribution boards, transfer switch panels, PLC cabinets, VSD cabinets, communications racks, and similar to be installed within the switchroom

  •  Wall space shall be allowed in the rooms to hang the LV rescue kit

  •  Wall space shall be allowed for a telephone, FIP, ASD, manual call points, fire beacon, fire siren, RJ45 sockets, and for GPOs

  •  High Voltage switchgear shall be arranged within the switchroom to allow for access from the rear as well as the front

  •  Compliance with AS/NZS 3000 as applicable

  •  Compliance with AS 2067 as applicable

2.2.6 Foundations

  • The switchroom building shall be mounted on a steel column structure designed to carry the full weight of the switchroom with all switchboards and switchgear installed.

  • The Contractor shall design the switchroom support columns and substructure as a complete structural system with limited vertical plane cross-bracing between supporting columns under the switchrooms. Supporting columns shall be designed as pin based transferring no moments to the footings. The clear height under the switchrooms shall be a minimum of 1800 mm, measured from the lower edge of the base frame to the AFFL. The location of cross bracing shall be to approval of the Company Representative.

  • The Contractor shall supply the support columns to site with the least amount of delay, such that they may be erected prior to the switchrooms arriving on site. The design of the attachment of the support columns to the building base frame shall be such that it can be bolted from the outside of the perimeter formed by the columns, without personnel having to be under any part of the building during the lifting phase of the site installation. All stainless steel holding down bolts, nuts, washers, etc. shall be supplied as part of the columns.

  • Columns shall be designed and manufactured to provide support around the perimeter of each transportable switchroom module. Columns or cross members located under the switchrooms shall be coordinated with site installed cable ladder design as approved. The column or support spacing shall be coordinated with the cable ladder and gland plate arrangement design under each switchroom so that cable entry is not restricted and cable ladder supports can be installed on site.

  • The Contractor may be required to design the switchroom civil foundations as required in the Scope of Work or Contract Documentation. Alternatively the civil foundations will be design by Others. To facilitate the detailed design of the switchroom civil foundations the Contractor shall supply all information as required, including details of the support points, loads imposed by the switchroom structure and connection arrangements between footings and switchroom support columns.

  • The switchroom building foundations shall be level, true and shall meet the level tolerances required by the high voltage switchgear manufacturers.

  • To prevent animals (cattle, kangaroos etc) from sheltering under the building the perimeter of the foundations shall be clad with material such as Colorbond® K Rail. The cladding shall be strong enough to withstand large animals rubbing against it.

  • A lockable gate shall be provided for access to the underside of the switchroom. Where required, locked access shall also be provided to access condensers for the air conditioning

2.2.7 Corrosion Proofing

  • All finished work shall have corrosion-proofed surfaces or, alternatively, be fabricated using corrosion free materials.

  • The base shall be hot dipped galvanised with all surface roughness eliminated. Areas where galvanising is damaged or removed and cannot be rectified by hot dipping shall be sand blasted and have two coats of cold galvanising applied.

  • Alternative systems of corrosion proofing for the base, such as epoxy coating, may be submitted for approved by the Company Representative. Where an alternative system is proposed, construction shall not commence until the Company Representative’s approval has been obtained. Longevity of the system shall be demonstrated and guranteed

2.2.8 Access

  • Exits from switchrooms shall comply with the requirements of the Building Code of Australia, AS 2067, and AS/NZS 3000.

  • As a minimum, one (1) personnel access door and one (1) double door for equipment entry shall be located at each end of the switchroom. Doors at each end of the switchroom shall also facilitate safe evacuation of personnel in case of a fire.

  • Personnel doors shall have an opening of not less than 800 mm wide and 2000 mm high.

  • The double external door shall have an opening of not less than 1600 mm wide and 2400 mm high.

  • The communications room shall have an opening of not less than 800 mm wide and 2200 mm high.

External doors shall be constructed with a high-density foam core sandwiched between Colorbond® metal sheeting of 0.5mm minimum thickness. External doors shall:

  •  Have appropriate fire ratings

  •  Open outwards to at least 180°

  •  They shall be designed by the Contractor to withstand the wind loading specified as determined in AS 1170, and be fitted with cyclone bars and pins

  •  Have key locks fitted to prevent unauthorised access. Locks shall be keyed to the site standard

  •  Be fitted with internal panic bars to be able to be opened from the inside without the use of a key even when locked against outside access

  • All doors leading to the outside of the building shall open outwards onto a landing at the same level as the switchroom floor.

  • Equipment is to be laid out such that the escape path from any location is direct and does not involve turns which are not in line-of-sight of an exit. No blind corridor shall be longer than 2 m

  • All exits including stairways shall open into a safe area, i.e. not into a sump bund, opposite a transformer bund, potential fire zone, or other hazardous or restricted area.

  • All doors from switchrooms to the outside shall open outwards onto a suitably sized landing at the same level as the switchroom floor.

  • Exit and emergency lighting shall be in accordance with AS 2293.

  • Internal access doors may be of hollow core construction and may open in either direction.

All door-sets shall comply with the following:

  •  Be fitted with automatic door closers and latches

  •  Be side-hung (hinged), with minimum three (3) heavy duty stainless steel hinges with removable pins

  •  The doors shall be painted to match the respective cladding

  •  Only the inter-leading internal doors between switchrooms of the same substation complex shall be fitted with windows. The glass shall be manufactured from tempered reinforced safety glass. Such a window shall not be larger than 65,000mm 2 clear opening area. Doors that lead outside shall not incorporate windows

  •  If the switchroom is within a larger building used for other purposes and the door opens into a fire escape or general egress area, or otherwise as required by AS/NZS 3000, the door shall be a fire door having a FRL of not less than -/120/30 to AS 1905. The completed fire-resistant door-set installation shall be certified as such

  • Fire rated doors shall be provided where they are part of a fire rated wall. The extent of fire rating shall be indicated on switchroom layout drawings. The fire rating shall be equal to or greater than the specified 120/120/120 fire rating of the wall.

  • Fire rated doors shall otherwise be equal to the standard door specified herein in every other respect.

  • Door frames and edging shall be heavy duty aluminium or powder coated Galvabond to a minimum thickness of 1mm.

2.2.9 Windows

  • No windows shall be allowed, except as part of internal access door-sets, refer section 2.2.8.

2.2.10 Stairways and Landings

  • Each switchroom shall be supplied complete with one or more equipment landing and stair assemblies. The equipment landing shall be designed for the installation and removal of the largest items of equipment in the switchroom. The landing shall be a minimum of 1800mm long and the full width of the building.

  • Equipment landings (with double doors) shall include removable handrails to allow large equipment to stand on the landing prior to it being placed in the switchroom.

  • A separate personnel entrance landing shall be provided as necessary to suit the switchroom layout.

  • Landings shall be designed to be attached to the switchroom building once it has been installed on site.

  • Landings shall be complete with handrails and kick plates to comply with AS 1657 and in particular shall extend at least 600mm clear of the cross traffic or door swing as per section 4.4 of AS 1657. They shall be large enough to allow personnel to open the door without having to descend the steps. The landings shall allow doors to open 180°. Double door landings shall have single width steps.

  • Landings shall be made of grid mesh and fitted with fixed boot scrubbers adjacent to each door to facilitate boot scraping and minimise mud ingress.

  • Landings shall be designed to facilitate hosing and washing down with water jets while avoiding consequent ingress of water to the switchroom.

  • As with landings, stairways shall comply with AS 1657 and shall be made of non-slip grid mesh. RL level for stair landing at ground level shall be coordinated with the site conditions, and confirmed with the Company Representative at the time of order. Unless advised differently, this RL should be assumed to be at the same height as the TOC for the support footings.

  • Stairways shall not exit into potential fire zones created by oil-filled transformers.

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