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Two times the capacity of equipment or systems required to support the critical load.


Operations conducted 7 days per week, 24 hours per day for 365 days a year.

A and B Electrical Supplies

Electricity provided through two separate cables from diverse electrical feeds.

AC Power

Alternating current power.

Abnormal Incident

An event that:

  - Directly and immediately impacts the functionality of the data centre.

  - Compromises the safety of an individual within the data centre and its environment.

  - Failure of any equipment or service that jeopardises the normal operation of the data centre.


Aspirated early warning smoke detection system. Sometimes referred to by the trademark VESDA.


A customer contract with Global Switch for the rent of space and / or power including:

  - Services Agreement (suites and cages)

  - Colocation Agreement (single racks)

Air Handling Unit (AHU)

A mechanical ventilation unit comprising fans and air treatment i.e. humidity control that supplies or extracts air from a space.

Amp (A)

A unit of electrical current.


An American National Standard that specifies the minimum requirements for telecommunications infrastructure of data centres and computer rooms including single tenant enterprise data centres and multi-tenant Internet hosting data centres. Further information can be found at www.tiaonline.org.

Anti-Pass-Back Doors / portal

A sophisticated control implemented on a set of doors or portals which prevent tailgating.


A gas suppression agent that is safe for human occupants. Works primarily by inhibiting oxidation of flammable materials and by physically removing heat from the fire.


The open space between rows of cabinets.

Annual Recurring Charge

The Annual Recurring Charge (ARC) is the yearly charge applied to all cross connect installations for the capacity management, control and administration of cross connect cabling infrastructure.


A drawing depicting the data centre infrastructure as it was constructed and subsequently modified.


American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) is an international engineering society. Further information can be found at www.ashrae.org.

Asset Categories

Definitive list of Global Switch asset types.


Automatic Static Transfer Switch (solid state device).


Automatic Transfer Switch.

Authorised Personnel

Customer Personnel who have been given authority to request specific data centre management activities and order services at Global Switch data centres through the Customer Portal.


An air balancing instrument primarily used for efficiently taking direct air volume readings at diffusers and grilles.


Global Switch Business Continuity Plan (please also see below Business Continuity Management).

Biometric Access

A technique used to authenticate an operator using physical characteristics, i.e. facial recognition, fingerprint scans, retinal scans, iris recognition and hand geometry.

Black Building Test (BBT)

A Black Building Test is a planned action to remove the utility (mains) power supply to a facility and confirm the stand-by systems operate as expected and protect critical load.

Blanking Panel

A device mounted in unused U spaces in a cabinet (rack), also called blanking or filler plates. Used to prevent bypass air, preventing cool air from moving through the cabinet without cooling the electronics.


Building Research Establishment Environmental Assessment Method (BREEAM) is an environmental standard that rates the sustainability of buildings. Further information can be found at www.breeam.org.


British Standards European Norm; a maintenance standard created by the British Standards Institute that has been normalised to European standards. Further information can be found at: www.bsi-global.com/en/Standards-and-Publications/About-BSI-British-Standards, www.cen.eu/cenorm/homepage.htm and www.iso.org/iso/home.htm.

Building Management System (BMS)

An integrated computer system that monitors and, where appropriate, controls a building's key engineering systems and critical services.

Business Continuity Management (BCM)

A holistic management process that identifies potential impacts which could threaten an organisation and provides a framework for building resilience with the capability for an effective response that safeguards the interests of its key stakeholders, reputation, brand and value creating activities. (Source: The Business Continuity Institute).


Device for holding IT equipment, sometimes also referred to as a rack.

Cable Baskets

Secure system to support either electrical or telecommunication cables.

Cable entry points (also known as chambers)

External entry points or chambers provided by Global Switch at the border of the data centre where communications infrastructure providers can interconnect their own external duct infrastructure. These entry points or chambers provide onward access to the duct or sub duct building entry systems to enable connectivity into the data centre.

Cable Management

The process of managing the routes of all cables entering and travelling within the data centre, ensuring that they are labelled and documented to facilitate installation and removal.


A secure and restricted area built within a Shared Data Suite to the customer's security requirements. Normally constructed of perforated sheet steel or wire mesh, hence 'cage'.

Carbon Footprint

A measurement of the volume of carbon dioxide generated by business operations, usually measured in metric tons.

Carrier Neutral

A carrier neutral data centre is independent of the telecommunications operators located in the facility and allows interconnection between multiple telecommunication carriers and / or colocation providers.


European Committee for Electrotechnical Standardization who are responsible for standardization in the electrotechnical engineering field. Further information can be found at www.cenelec.eu.

Change Control Process (CCP)

A Global Switch procedure to mitigate and or control the effect of human error in the data centre maintenance, repair and / or installation of systems and / or equipment.


Chilled Water.


Computational Fluid Dynamics (CFD) is a numerical analysis technique commonly used in the analysis of airflow in data centres.

Close Control Units (CCUs)

Equipment delivering cooling to technical spaces within the data centre.


A Computerised Maintenance Management System (CMMS) enables Global Switch to manage the maintenance of Global Switch assets within the data centre.

Cold Aisle

An aisle where rack fronts face into the aisle. Chilled airflow is directed into this aisle so that it can then enter the rack fronts to provide a cooling effect to IT equipment contained within the racks.

Co-location (CoLo)

Housing of IT equipment in a shared area, available from a single rack upwards.

Computer Room Air Conditioner (CRAC)

The perimeter cooling equipment installed within each data suite.


The provision of facilities such as cables, devices or bandwidth to support voice and data connections.

Corrective Maintenance

Also known as Reactive Maintenance, these include:

  - Maintenance services arising from an unplanned fault or event in respect of Global Switch assets.

  - Repairs, small works, and other similar non-specialist handyman tasks in relation to the building fabric.

In each case provided or managed by Global Switch and which are in addition to the Planned Preventative Maintenance Services (PPMS).

Corporate Governance

The system / process by which the directors and officers of an organisation are required to carry out and discharge their legal and regulatory accountabilities and responsibilities.


Control of Substances Hazardous to Health (COSHH) is a law that requires employers to control substances that are hazardous to health (applicable in the United Kingdom). Further information can be found at www.hse.gov.uk/coshh.

Critical Environments Programme (CEP)

The Global Switch Critical Environments Programme (CEP) is a comprehensive programme that governs the operations and maintenance of all Global Switch critical infrastructure to a common global set of best practice standards, systems, policies, processes and procedures. The CEP is the mechanism for maintaining and continuously improving the quality of operations and maintenance programmes.

Critical Facility Equipment

Critical Facility Equipment includes the following:

  - All electrical equipment from the site utility incomer to the individual distribution panels and power circuits within the technical customer areas including generators, battery plant and UPS systems.

  - All mechanical equipment that provides cooling to the essential and none essential heat loads within the data centre including air handling units, heat exchange equipment, pumps and piping.

  - Protective equipment including fire and smoke detection and suppression systems, leak detection, security systems and remote monitoring equipment.

  - Control equipment including Power Monitoring Systems, Building Management Systems or other systems that are in any way connected to the Critical Facility Equipment for control and / or monitoring purposes.

Critical Facility Works Rules

Global Switch Critical Facility Works Rules apply to work being performed on or around Critical Facility Equipment which are authorised by Global Switch under a Method of Procedure (please see MOP below).

Critical Load

A system that directly affects business operations so must be kept running even in the event of mains power failure, i.e. is uninterrupted.

Critical Spare Part(s)(or list)

A Critical Spare is a vital component part which may be subject to failure in service and is used in plant and machinery necessary to service a critical environment. Critical Spares would typically be required to affect an immediate repair on site at the building.

Cross Connect

Any cabling connection provided to establish voice or data connectivity and which traverses common areas or pathways inside a Global Switch data centre. Copper cabling containing multiple twisted pairs but a single sheath and connector per end, a single coax cable or up to a pair of fibre cables used to establish a single connection (Tx-Rx, Rx-Tx) shall be considered an individual Cross Connect.

Customer Incident Report (CIR)

A Global Switch report for distribution and communication to customers affected by an Incident.

Customer Portal

An online Global Switch customer facing system to facilitate and enhance the provision and management of Global Switch products and services by customers.

Customer Portal Administrator

A customer representative that has administrator privileges for their company in respect of the Customer Portal. Personnel with this type of user account are able to make all types of customer requests and create other administrator users for their company within the Customer Portal.

Customer Services Handbook (CSH)

A document for Global Switch customers that sets out the measures determined by Global Switch as necessary to mitigate any risks to the environment, business, operational efficiency, security and physical well-being of Global Switch data centres, personnel at those data centres and to protect its customers' on-going business operations.

Daisy Chain

The inter-linking of electrical sockets from one electrical power distribution strip to another is not permitted. This is sometimes termed as 'Daisy Chaining'.

Data Centre

A Global Switch facility.

Data Risers

Conduits between floors or areas within Global Switch data centres for the purposes of running cross connects or other associated data cabling.

DC Power

Direct Current power.

Down Flow Unit (DFU)

Computer room Air Conditioning unit used to distribute conditioned air within the underfloor plenum. Also known as CRAH.


Diesel Generator.

Disaster Recovery Sites

Off-site locations set up by organisations to allow them to re-establish operations and continue to trade in the event of a disaster.


Diesel Rotary Uninterruptible Power Supply.

Emergency Control Procedures

The procedures implemented by Global Switch which all Personnel must adhere to in the event of an emergency.


Electromagnetic Interference.


Energy Management System.


An Emergency Operating Procedure (EOP) is a Global Switch process document within the Critical Environments Programme outlining procedures to be followed in an emergency or scenario test.


Emergency Power Off (EPO) is implemented on a per equipment or per location basis to interrupt the power supply to equipment immediately. This can be triggered by human operation of an EPO button, or by automatic system operation.


Ethernet is a packet based network technology that segments data and transports it inside a set of frames. Throughput ranges from 10 megabits per second to 100 gigabits per second with further development expected.

Evacuation Muster Point

An external gathering point used in the event of an evacuation of a Global Switch data centre.

Evacuation Procedure

The procedure by which a Global Switch data centre is evacuated in the event of an emergency.


A Global Switch data centre.


Facilities Management, and also the delivery of Facilities Management services.


A gas suppression agent that works primarily by inhibiting oxidation of flammable materials and by physically removing heat from the fire.

Front Desk (also termed Reception)

The principal point of entry into a Global Switch data centre with 24x7x365 manned presence.

Goods In

See Loading Bay.


High Availability refers to a system or a component that is continuously operational for a long duration. Measured relative to 100% availability.

Hazardous Substances

Solids, liquids, or gases that can harm people, other living organisms, property, or the environment.


High Efficiency Particulate Accumulation (HEPA) is a type of vacuum air filter that catches a very high percentage of all particles that could damage or destroy sensitive data centre equipment. These filters are able to trap extremely small particles missed by other types of filters.

Horizontal Distribution Area (HDA)

The horizontal distribution area (HDA) is the space that supports cabling to the equipment distribution areas. The LAN, SAN, console and KVM switches that support the end equipment are typically located in the horizontal distribution area for nearby equipment or the entire computer room if the computer room is small.

Hot Aisle

An aisle where cabinet backs face into the aisle. Heated air from the equipment in the cabinets is exhausted into this aisle.

Hot Spot

An area, typically related to a rack or set of racks, where ambient air temperature is above acceptable or specified levels. Typically caused by poor airflow management (insufficient cool air supply or an excess of recirculation).

Hot Works

The use of any smoke or flame producing apparatus, for example: hot air guns, soldering irons, welding or Oxy-Acetylene equipment.


High Sensitivity Smoke Detector (HSSD) - sometimes referred to using the trade mark VESDA (Very Early Smoke Detection Apparatus).


An electrical supply of greater than 1,000 Vac between conductors.


Heating, Ventilating and Air Conditioning (HVAC).


An Intermediate Distribution Frame is used in telecommunications equipment systems and networks.

Inlet Air

The air that enters the IT equipment so to cool the respective piece of equipment.


An inert gas consisting of nitrogen, argon, and carbon dioxide that is used for fire suppression, and is electrically non-conductive.


Infrared (IR) is invisible radiant energy with longer wavelengths than those of visible light, extending from the nominal red edge of the visible spectrum at 700 nanometres.

In Row Cooling

Cooling equipment that delivers targeted cool air. Usually positioned between equipment cabinets in a row, but can also be placed within a cabinet.


The Internet Protocol is the principal communications protocol which forms the infrastructure of the internet and enables interworking between devices.


International Organization for Standardization (ISO) is an independent, non-governmental membership organization and the world's largest developer of voluntary International Standards. ISO International Standards ensure that products and services are safe, reliable and of good quality. Further information can be found at www.iso.org.

ISO 9001

A Quality Management System. Defines a quality management system to help businesses manage processes efficiently and effectively and to incorporate best practice methodology.

ISO 14001

An Environmental Management System. Defines environmental management processes to help businesses manage their environmental responsibilities.

ISO 27001

An Information Security Management System. Provides a systematic approach to security information management. Assists businesses in identifying, analysing and addressing information security risks.


An isolation is an action performed by Global Switch to remove a potential hazard from an installation, most often used prior to a maintenance operation. Typical examples include isolation of the power supply or a fire protection system. Returning the installation to an operative state is usually referred to as removal of the isolation, re-energisation or re-instatement.


Key Performance Indicator. A measurable value that demonstrates how effectively a company is achieving key business objectives.


A derived unit of power (Joule/second). 1 kilowatt = 1,000 watts. In electrical circuits, power = current (amps) x potential (volts), and in AC electrical circuits power = power factor x current x volts.


A unit of energy equivalent to one kilowatt (1 kW) of power sustained for one hour.


A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. Used in the transmission of data along fibre optic cables.


Latency is the amount of time it takes for a packet of data to get from one designated point to another.


Leadership in Energy and Environmental Design (LEED) is a set of rating systems for the design, construction, operation, and maintenance of buildings with strong green credentials. Further information can be found at www.usgbc.org/leed.

Loading Bay (also termed 'Goods In')

A point of entry into a Global Switch data centre allowing, in most instances, vehicle access for the loading and unloading of deliveries.

Local Loop

The physical connection from the telecom carrier's Point of Presence (POP), and the subscriber's premises. The local loop can be provided over any suitable transmission medium.

Lockout-Tagout (LOTO)

A safety procedure which is used to ensure that potentially dangerous machines or sources of energy are properly shut off and not able to be energised or started up again prior to the completion of maintenance work. The relevant circuit breaker or operating switch is locked in an off position using a padlock and identified with a tag. These remain in place until removed by the technician following completion of the works.

Low Smoke Zero Halogen (LSOH, LSZH)

Refers to the classification of material used in cable sheathing. In the event of a fire, LSOH cable will emit lower levels of smoke, and non-toxic levels of halogen based gases.


An electrical supply of less than 1,000 Vac between conductors. (Low Voltage).


Mechanical and electrical.

Main Distribution Area (MDA)

The main distribution area (MDA) is the central space where the point of the distribution for the structured cabling system is located. The data centre shall have at least one main distribution frame. The core routers and core switches for the data centre network are often located in or near the main distribution area.

Managed Diverse Fibre Ingress

Multiple entry points for fibre running into the building which are owned and managed by Global Switch.

Material Safety Data Sheet

A form containing data regarding the properties of a particular substance; used to estimate necessary precautions. Sometimes referred to as Material Safety Data Sheets (MSDS).


Physical objects, stored data such as paper, hard disc drives, tapes and compact discs.

Meet-Me Rooms (MMR)

Highly secure areas in Global Switch data centres specifically designed to house telecommunication providers' network equipment and cable termination infrastructure.

Metered Power

A way of measuring power consumption that ensures the customer only pays for the amount of power used over a designated period of time.

Method of Procedure (MOP)

A Method of Procedure (MOP) forms part of Global Switch's Critical Environments Programme describing the detailed actions which must be undertaken in the carrying out of Mechanical and Electrical services.

Method Statement

A 'Method Statement' is a detailed document describing the works or activity which will bring about a change in operating condition, including any mitigating steps required to make the work safer as highlighted in a risk assessment.


Critical operational and / or business support activities (either provided internally or outsourced) without which an organisation would quickly be unable to operate.


Activities designed to reduce or eliminate risk to persons or property or to lessen the actual or potential effects or consequences of an incident.

Multimode Fibre

Multimode fibre is a physical transmission medium used in data networking and supporting high bandwidths, typically used within buildings and supporting distances of up to 500m.


A mega volt amp is a unit of apparent power. The apparent power refers to the total current and voltage in an electrical circuit. The term is preferred in descriptions of total electrical power in installations, and it captures both true and reactive power in an electrical circuit. It is the common rating used in major electrical installations, such as transformers and generators.


A megawatt is a measure of real power equal to one million watts. Often used to describe the power capacity of data centre or an installation within a data centre.


The required capacity of equipment or systems to support the critical load; refers to the sizing of infrastructure capacity to support business operations.


N+1 redundancy is a form of resilience that ensures system availability in the event of component failure. Components (N) have at least one independent backup component (+1).

Non Critical Spares

A component or spare part (other than consumables and Critical Spares) that would need to be replaced in the event of a plant and / or machinery failure.

Occupational and Health and Safety Standards (OHSS)

Country specific Occupational and Health and Safety Standards (OHSS) regulations and practices which are required to be complied with when working in Global Switch data centres.


An original equipment manufacturer is the manufacturer of assets used by Global Switch within the data centre. Maintenance is performed on such assets by contractors appointed by Global Switch which could include the OEM manufacturer, a specialist contractor, or the FM contractor.

OHSAS 18001:2007

Occupational Health & Safety Management (OHSAS) is an internationally-applied British Standard for occupational health and safety management systems. It exists to help all kinds of organisations put in place demonstrably sound occupational health and safety performance.

Optical Distribution Frame (ODF)

An Optical Distribution Frame (ODF) is a passive piece of equipment where a fibre cable can be terminated to provide easy access to individual fibres using standards-based interface types.

Optical Fibre

Sheathed strands of glass fibre used to transport information (digital signals) from one point to another.


Power Distribution Unit (PDU) is a point of electrical connection to a customer's cabinets.

Permanent Access Cards (PAC)

A Global Switch data centre access card allocated to a particular individual. It must be carried and displayed by the individual at all times and allows the individual access to the data centre for 24x7x365 without the need for pre-booking or clearance by security.

Permanent Access Schedule

A list of Permanent Access Card holders to a Global Switch data centre which is available via the Customer Portal.

Permit Holder

Personnel nominated on a Global Switch Permit to Work as being responsible for the work that is due to be or is being carried out.

Permit to Work (PTW)

A Global Switch document that controls access to a data centre for the purpose of undertaking work.

Personal Protective Equipment (PPE)

Protective clothing and other devices designed to protect an individual while in potentially hazardous areas or performing potentially hazardous operations.


Portable fire-fighting equipment.

Planned Preventative Maintenance (PPM)

A series of planned maintenance works in a Global Switch data centre against a specific timetable or schedule. The work tickets are managed by a computerised system and are normally accompanied by a documented procedure describing the work to be performed and permits required or isolations to be implemented prior to the work taking place.


Plenum refers to a housing that is at a positive pressure to the surroundings and is commonly used for air distribution. This space is commonly found between two ceilings or between a raised floor and the actual floor.

Point of Presence (POP)

The locations at which a carrier establishes itself to provide access to its network infrastructure, to interconnect customers to its services, or to interconnect with other carriers or third parties for the purpose of exchanging network information and traffic.

Power Usage Effectiveness (PUE)

A metric used to determine the ratio of total facility energy to power IT equipment energy. Total facility energy is defined as the energy dedicated solely to the data centre (e.g. the energy measured at the utility meter of a dedicated data centre facility or at the meter for a data centre or data room in a mixed-use facility). The IT equipment energy is defined as the energy consumed by equipment that is used to manage, process, store, or route data within the compute space. A ratio closest to unity is preferred. There is considerable misuse of this term in the data centre industry and great care is required when using or quoting such metrics.

Private Suite

A highly flexible, resilient and self-contained private data centre space within purpose-built facilities.

Proximity Card System

A computer controlled access system using electrically controlled locks that are released when an authorised card is placed against a proximity reader.

Purchase Order (PO)

The reference number issued from customers to Global Switch when purchasing a product or service.


Radio Frequency Interference or Request For Information.

Raised Flooring

A flexible suspended access flooring system mounted above concrete floor slab with removable tiles. The void that is formed provides an air plenum and space for cable basket and other building services to pass underneath the finished floor level.


See Risk Assessment and Method Statement.


Following completion of work which has required isolation of the whole or part of a system, a removal of the isolation, re-energisation or re-instatement is required.


See Front Desk.

Request User

A group of users within the Global Switch Customer Portal which are permitted by a Global Switch customer to request products and services through the Customer Portal.


Root Cause Analysis.


Having one or more back-up components or systems available in case of failure of the prime system. See N, N+1.

Registered Email Address

The email address of a customer's 'Authorised Personnel'; associated with the authorisation levels each individual has in respect of data centre management requests and ordering of Global Switch services through the Customer Portal.

Restricted Areas

Space(s) within the data centre where sensitive business operations take place and access is strictly controlled.

Restricted Materials

Any material prohibited from entering technical space due to the potential for it to cause harm or damage to the operation of equipment within the technical space.

Risk Assessment and Method Statement (RAMS)

A RAMS document details the way a work task or process is to be completed. It contains a risk assessment highlighting the significant hazards and control measures required to prevent injury or ill health whilst carrying out the task. The method statement should include a step by step guide on how to do the job safely. The method statement must also detail which control measures have been introduced to ensure the safety of anyone who is affected by the task or process.

Risk Management

The culture, processes and structures that are put in place to effectively manage potential opportunities and adverse effects.

Risk Mitigation

A selective application of appropriate techniques and management principles to reduce or mitigate either likelihood of an occurrence or its consequences, or both.

Safe Systems of Work (SSW)

A Global Switch process detailing how work will be carried out in a safe manner.

Services Catalogue

A list of prices for specific services available at Global Switch data centres.

Service Level Agreement (SLA)

A formal agreement between a service provider (whether internal or external) and their customer (whether internal or external) which covers the nature, quality, availability, scope and response of the service provider.

Service Provider Neutral

Not allied to any telecommunications or IT service provider, which means the customer has complete freedom to select their provider of choice.

Set Point

A Set Point is the value against which the variable that is being controlled is compared in an engineering control system. Temperature and humidity set points are common in data centre cooling systems.

Shared Data Suite

A suite for multiple customers sharing services with optional secure caging.

Single Mode Fibre

Single mode fibre is a physical transmission medium used in data networking supporting high bandwidth over very long distances.

Single Phase

Single Phase power refers to a two wire Alternating Current (AC) electrical circuit. Typically there is one 'line' conductor and one neutral conductor. In most jurisdictions, 230V is the standard single phase voltage with one 230V power conductor and one neutral conductor. Current flows between the line conductor (through the load) and the neutral conductor to provide power. These two conductors are normally accompanied by an earth conductor for reasons of safety and electrical protection.

Site Accident Book

A book held at each Global Switch data centre for the reporting of all accidents and near misses.

Site Induction

The process whereby each person entering a Global Switch data centre is educated and/or briefed on relevant health and safety and safe working practices to ensure adherence to relevant legislation and to comply with the strict working procedures required in a mission-critical data centre environment.

Site Services

External services that enter the data centre, for example, services such as power and connectivity.


A Scope of Service is a document associated to a specific asset category outlining the frequency and the actual steps required for Planned Preventative Maintenance for that type of asset.

Specialist Personnel

A professional resource provided by Global Switch to facilitate customers ad hoc requirements offering, but not restricted to; technical advice, technical engineering support, security management and programme management.

Specialist Personnel Charge

The charge to a customer associated with 'Specialist Personnel'

Splicing Chamber

A large highly secure pit or room where telecommunication cables are joined. Used to change from external grade cables to internal grade LSOH cables.


Single Point of Failure.

Standard Operating Procedure (SOP)

Procedures that are undertaken in Global Switch data centres on a day-to-day basis to ensure the safe and continuous running of the data centres.

Statutory and Regulatory Requirements

Local country, region or location specific legislative requirements that must be followed or put in place.

Structured Interconnect System (SIS)

Global Switch's managed cabling infrastructure.


Static Transfer Switch (solid state device).

Sub Duct

Duct connectivity between a telecommunication provider's external chamber or pit and the Global Switch operated chamber or entry point into the data centre.

Sub Floor

The open area underneath a raised computer floor, also called a sub-floor plenum.


The resource provided by Global Switch to oversee work or visits.

Supervision Requirement

The term used by Global Switch to estimate the resource that will be provided to oversee work or visits.

Supervisory Services Charge

The charge to a customer associated with 'Supervision'.


Static Uninterruptible Power System. A solid state UPS system which uses pre-charged batteries as the source of energy in the event of a power failure.

Supply Air

The cooled airflow emitted from air conditioning equipment.

Technical Real Estate

Purpose-built, resilient environments in which IT equipment is securely housed.

Three Phase

Three Phase power refers to three wire Alternating Current (AC) power circuits. Typically there are three (L1, L2, L3) line conductors (120 degrees out of phase with one another) and one neutral conductor.


The Telecommunication Industry Association represents manufacturers and suppliers of high-tech communications networks. Further information can be found at www.tiaonline.org.

Tie Cable

A cable that connects two distribution points within a network.

Tier 1

Single path for power and cooling distribution, no redundant components and 99.671% availability (as defined by Uptime Institute).

Tier 2

Single path for power and cooling distribution, redundant components and 99.741% availability (as defined by Uptime Institute).

Tier 3

Multiple power and cooling distribution paths, but only one path active, redundant components, concurrently maintainable and 99.982% availability (as defined by Uptime Institute). Also known as concurrently maintainable.

Tier 4

Multiple active power and cooling distribution paths, redundant components, fault tolerant and 99.995% availability (as defined by Uptime Institute). Also known as fault tolerant.

Tier 1 Market

A Tier 1 market is a principal metropolitan business, communication and internet hub.


A unit of space in a cabinet (rack), equal to 4.4cm. The vertical dimension of racks and IT equipment is often specified in U, for example, 42U.

Uninterruptible Power Supply (UPS)

A system which provides continuity of power in the event of a mains power failure. The source of energy in UPS systems is typically battery, generator and / or kinetic.


See HA (High Availability).

Uptime Institute

A commercial organisation that developed a 'Tier' system adopted by most data centres. Further information can be found at uptimeinstitute.com.

Valid Photo Identification

Acceptable forms of identification at Global Switch data centres, including a Passport or National Identity Card, photo Driving License, Government issued photo ID or company issued photo ID with a bank card.

VESDA Systems

Very Early Smoke Detection Apparatus.


An individual that has been authorised to access a Global Switch data centre, or specific areas of the data centre and who has not been issued a Permanent Access Card.

Visitor Access Card (VAC)

A Global Switch access card issued to a visitor which allows entry to the data centre or specific areas of the data centre for a single day. The card must be returned to Global Switch security prior to the visitor departing the data centre at the end of each day.


Waste Electrical and Electronic Equipment (WEEE) is a European Union directive that designates the safe and responsible collection, recycling and recovery procedures for all types of electronic waste.


Any activity within the data centre which may potentially affect or disrupt Global Switch or customer operations.

Work in a Confined Space

Any work in an enclosed or partially enclosed space as defined by local statute.

Work on Electrical Systems

Any work on Global Switch electrical plant, distribution pathways or customers' Power Distribution Units (PDU) that could impact Global Switch's infrastructure.

Workplace Substance Register

The register of chemical or hazardous materials stored within the data centre (see COSHH).

Works Supervision

The resource provided by Global Switch to oversee work.

Zinc Whiskers

The name given to very small particles of zinc that resemble hairs which can appear as a result of zinc electroplated materials residing in the data centre. Most commonly found on floor tile components and equipment brackets, they are considered a risk to continuous operation of IT equipment because if dislodged and able to enter IT equipment, can cause electrical short circuits.


A location or group of locations within a Global Switch data centre. It is normally used when discussing customer data suites and cages.

Zone Distribution Area (ZDA)

The zone distribution area should be limited to serving a maximum of 288 coaxial or twisted pair connections to avoid cable congestion, particularly for enclosures meant to be placed overhead or under floor tiles.