Best Practices in Data Center Relocation

Best Practices in Data Center Relocation

Data center relocations are complex initiatives that cross every aspect of IT and the business. Preparing for success requires an in-depth understanding and proper documentation of all facets of the interrelationships between the technology infrastructure and the supported business operations.

Many organizations make significant investments in new data center facilities, resulting in a state of the art physical plant. A frequent oversight, however, is carrying poor processes, procedures, architecture and documentation into the new site. In order to achieve the desired availability of applications and data, the maturity level of the IT infrastructure and processes must meet or exceed the design criteria of the facility.

Organizational Readiness Determines Scope

In order to understand the scope of preparations and investment required for a smooth relocation, an organization must first evaluate its readiness to undertake the initiative. The maturity of an organization’s IT infrastructure processes, procedures and documentation has a direct correlation to the complexity of the undertaking, and the level of complexity is a major factor in an initiative’s cost and risk to the business.

Organizations with well-documented, actively-managed asset management, disaster recovery, monitoring and management, and change control programs have the essential elements required to successfully complete the data center relocation. They will not have to invest in the discovery, validation or development of information and processes in order to prepare.

Conversely, gaps in these processes and documentation must be addressed prior to or in conjunction with the project. Failure to address gaps will introduce a high degree of risk to the project and could lead to outages that negatively impact the business.

Five Steps to a Successful Data Center Relocation

Step 1 – Perform a readiness assessment
Performing a best practices check-up for infrastructure management provides a baseline of the organization readiness to undertake this initiative. The objective is to evaluate the accuracy and completeness of processes, procedures and documentation. Focus areas include:

§ Support Structure – Are problem management, notification and escalation processes current and documented?

§ Service Level Agreements – Do they exist? Are they documented? Are they current?

§ Documentation – Do the five basic documents (configuration, startup, shutdown, backup, recovery) exist for each asset? Is there a central repository? Is there a document control system? Is the documentation current?

§ Asset Management – Does a current system exist that reflects all assets and related portfolio information?

§ Maintenance Contracts – Are these consolidated into a single data source, preferably the asset management system? Do the maintenance contracts reflect service levels proportionate to criticality and usage of the assets? Are contract expirations proactively managed?

§ Financial Management – Does all information related to environment lifecycle costs exist in a central repository (asset management system)? Does a total cost of ownership (TCO) model exist for each asset?

§ Change Control – Is there an actively managed process that tracks and audits all changes to the environment, including facilities, hardware, software, applications and data structures?

§ Architecture – Is the IT architecture well defined and documented? Is the architecture team involved in the design and validation of initiatives?

§ Capacity Planning – Does an automated system exist to track the usage baseline and deltas in the environment at a component level?

§ Performance Management – Does an automated system exist to track the baseline and deltas of the environment’s performance to a component level?

§ Monitoring and Management – Does an automated system exist to track the availability and service levels of the IT environment? Are support and escalation procedures automated and current?

§ Business Initiatives – Is there an overall perspective on the parallel initiatives that will be undertaken by IT and the business during the life of the data center relocation project? Are the impacts and resource requirements understood and documented?

§ Stakeholder Management – Have the basic requirements and value proposition for the data center relocation project been communicated to the business and internal/external partners? Has a communication plan been established and implemented?

§ Resource Availability – Is there a commitment of resources from each of the stakeholder groups in direct relation to the project timeline?

§ Industry Regulations – Are the compliance ramifications of the project understood and overseen by a certified organization?

§ Logistics – Have the decisions related to the location of the destination facility been finalized? Is there a strategy for the location of assets by class by facility?

§ Relocation Project – Has the project executive defined the basic initiative timeline? Is there a dedicated project manager? Does a corporate project management office (PMO) exist and has this initiative been registered with the PMO?

§ Disaster Recovery Plans – Do current validated plans exist for each environment? Because a data center relocation is essentially a managed disaster recovery event for which the IT environment will be reestablished at a different location, disaster recovery is the most pertinent area to the success of the project. A thorough disaster recovery plan provides key information about the interrelationships between the infrastructure and the business, the criticality of applications and data, and the mechanisms to mitigate risk.

Based on the project timeline, a determination needs to be made for each gap area on whether to implement a long-term or interim solution.

Step 2 – Assess the environment

This phase of the project involves gathering, combining and correlating information about assets and their use in support of the business. Analogous to a disaster recovery plan, this step baselines the environment and begins the process of asset classification. Each asset must be identified and the portfolio of information regarding its use and interrelationship to the whole environment must be established and documented. The output of this phase is the asset repository that reflects the current inventory, technical and business interrelationships, and supporting asset lifecycle information. Best practices include automated asset discovery and tracking, and the use of an industry standard repository such as a configuration management database (CMDB) that is capable of providing a comprehensive view of all aspects of each asset.

Step 3 – Design, validate and plan the project

Building upon the assessment, each asset must be correlated to the business function it supports. This step parallels the disaster recovery process of defining recovery groups; for the sake of this project, these groups will be referred to as “move groups.” Each move group represents a consolidated collection of assets that support a key business function or IT support function.

Each move group is analyzed for its criticality to the business and assigned a corresponding ranking. The disaster recovery plan for each move group is consulted, along with the technical architecture employed for availability and recovery. The result is a relocation methodology tailored for each move group based on the service level agreement, risk mitigation capabilities that currently exist and an approved business case for additional investment required to support availability or limit risk during the relocation.

The output of this project phase will be an overall project plan that includes detailed task plans, time budgets, and resource and contingency plans. A relocation calendar should detail the timing of move events in relation to business initiatives and cycles. A communication plan and command center structure should be documented and validated with all stakeholders.

Step 4 – Implement the plan

This phase is where the detailed analysis and planning pays off. Each stakeholder should understand his or her role and tasks. Decisions regarding contingencies and timelines have been established. The command center coordinates the activities, tracks and communicates progress, and performs problem management and escalation coordination. Successes and failures are documented and utilized post-relocation to improve the process for subsequent events.

Step 5 – Manage the environment post-relocation

Upon completion of the data center relocation, it is imperative to take one additional step: the incorporation of knowledge, updated processes, procedures and documentation into the normal support structure of the IT infrastructure. The relocation project will have validated or generated current information about the IT infrastructure. As change is constant in information technology, this information will have a limited shelf life. In the normal course of business, these processes, procedures and documentation all too often become a low priority for compared to the demands of the business on IT organizations. Quickly incorporating this information and implementing a process to continually refresh it will achieve a far greater long-term result than solely the relocation of assets.

The Long-term Benefits of a Successful Data Center Relocation

The benefits of carefully planned and executed data center relocation go well beyond what meets the eye of the user or customer. Done correctly, the end result is not only a seamless transition for the business, but also the creation of a set of business continuity disciplines that can validate or provide groundwork for disaster recovery and business continuity planning – as well as IT and physical security, asset management, systems documentation, change control, operating standards and processes, capacity planning, maintenance and license management, service and operating level agreements, business alignment and data center facility management.

In other words, successful data center relocation can completely transform the overall operating environment – its processes, procedures, documentation and personnel – in a way that has significant, lasting benefits for an organization’s disaster recovery readiness as well as day-to-day operational efficiencies.

About the Author:

As the director of Forsythe's data center relocation services practice, Fred Latala is responsible for the company's overall data center relocation strategy, vision, best-practice models, and the quality of solutions delivered. Latala has more than 20 years of experience in internal and external IT management roles.

By Fred Latala

Harmonic

Harmonic Studies
Harmonic studies are performed to determine harmonic distortion levels and filtering requirements within a facility. Field measurements and computer simulations are used to characterize adjustable-speed drives (ASDs) and other nonlinear loads and simulations are then performed to determine the filter specifications and effectiveness. The application of harmonic filters will significantly alter the frequency response of the power system. An evaluation of the harmonic voltage and current limits, (e.g., IEEE Std. 519) is completed to determine the effectiveness of the proposed filter installation.

The potential for harmonic distortion problems is dependent on two important factors:
-The level of harmonic generation which can be associated with loads in the plant. Harmonic currents are generated by loads which have nonlinear voltage-current characteristics. The number and sizes of these devices at a given bus determines the level of harmonic current generation.
-The system frequency response characteristics. The frequency response at a given bus is dominated by the application of capacitors at that bus. Series reactors for transient control or harmonic control significantly change the frequency response. Problems occur when the system response exhibits a parallel resonance near one of the harmonic components generated by the loads on the system (usually the 5th or 7th harmonic). Resistive load provides damping near these resonant frequencies.

The combination of these two factors determines whether or not a harmonic problem will exist at a particular bus. It is also possible for harmonic problems to occur at buses remote from the harmonic source if local resonances exist. If capacitors are applied at any locations that have large adjustable-speed drives, the potential for resonance problems must be considered carefully. A harmonic study evaluates these concerns as described in the following sections:

Develop Base Case Harmonics Model
The first step in a harmonic study is to develop a system model to be used for the analysis. The model is developed from the oneline diagrams, the electrical equipment data (transformers, cables, machines, etc.), the utility system characteristics, and the load information. The result is a database that includes the following elements:
-Representation of the utility system supplying the facility. This system can be represented as a simple equivalent as long as there are no switched capacitors. However, it is quite likely that the utility does have switched capacitors on the supply system and these must be represented.
-Step-down transformers (ratings and nameplate impedances).
- Important low voltage circuits (specifically ASDs).
-Load data for each bus (kW, kVAr, kVA).
-Capacitor data (level of compensation, kVAr).

The electrical database developed at this stage is used for the development of the harmonic analysis model of the system. The model must include important connected capacitors, cable capacitances, transformer characteristics, reactor values, motor representations, and an equivalent representation for the utility supply system.

Harmonic measurements are very useful in that they provide information necessary to characterize the loads as well as provide a means for verifying the harmonic model. Measured harmonic currents are used as input to the model and simulated harmonic voltage distortion levels are then compared with measured values to determine the accuracy of the model.

The model is developed for the SuperHarm® computer program used by Electrotek for harmonic analysis. This program permits convenient analysis of system frequency response characteristics as well as direct representation of important harmonic sources in order to simulate system harmonic levels.

Harmonic Measurements
Harmonic measurements are an important part of the overall investigation for a number of reasons. Most importantly, the measurements must be used to characterize the level of harmonic generation for the existing nonlinear loads. Voltage and current harmonic levels are measured at multiple sites to accomplish this. It is important to accurately document system conditions at the time of the measurements so that the results can be used to verify analytical results.
The specific objectives of the measurements include:
-Determine the harmonic generation characteristics of the nonlinear loads (e.g., dc drive waveform below). This is done by performing current measurements at a variety of locations within the facility. Three-phase measurements are made so that characteristic and non-characteristic (triplen) harmonic components can be determined.
-Determine system response characteristics for particular conditions. Voltage measurements are used in conjunction with the current measurements to characterize system response for specific system conditions. These conditions are then be the basis for verifying the analytical models.
-Determine the background harmonic voltage and current levels.

The measurements typically are performed over a period of 1-5 days in order to assure that adequate data is collected to characterize the system operation and for verification of the analytical models.

Develop Harmonic Source Models
A list of nonlinear loads is compiled and representations of these loads as harmonic generating devices is developed. Loads at the individual buses are categorized as follows:
-ac Motor Loads
-Resistive Loads
-Adjustable-Speed Drives
-SCR Bridge Rectifiers (furnaces)
-dc Motor Drives
-Welding Loads
-Other Loads
The motor loads and resistive loads have important impacts on the system frequency response but they are not sources of harmonic distortion. These representations are used in conjunction with the system model to estimate harmonic levels throughout the facility.

Determine System Frequency Response Characteristics
Simulations (frequency scans) are performed to determine the frequency response characteristics looking from the 480 volt buses. Output consisting of magnitude and phase angle for the driving point impedance is produced. The effect of important system parameters (capacitors, loads, transformer sizes) is evaluated and the potential for problem resonance conditions is determined (5th or 7th harmonic resonance is the most important). Tabular and graphical results (e.g., scan figure below) of various switching conditions is prepared so harmonic resonance conditions can easily be identified.

If problem conditions are identified at a given bus, filter designs are developed to alleviate the resonance problems. These filter designs should be coordinated closely with the transient analysis.

Estimate System Harmonic Voltage and Current Levels
The frequency scan cases identify system conditions that can cause harmonic problems due to resonance conditions. These system conditions are emphasized when evaluating the response to estimated harmonic current injection levels. The simulations to estimate actual harmonic distortion levels include representations of the harmonic generating devices and the important system conditions. The output for these cases consists of individual harmonic levels (harmonic spectrums), bus voltage distortion levels, current distortion levels, RMS voltage and current levels, and important waveforms.
Severe Secondary Bus Voltage Distortion
Expected harmonic voltage distortion levels are evaluated based on recommended limits outlined in IEEE Std. 519. This standard states that the bus voltage distortion level should be limited to 5%. This limitation should prevent any harmonic problems with process controls, capacitors, transformers, or adjustable-speed drive controls.
One of the most important impacts of the harmonic currents caused by nonlinear loads and system resonances is the increased heating in system equipment. Transformers are the most important devices affected but cable ratings could also be impacted. Spreadsheets are developed during the study to evaluate the transformer and cable derating required to accommodate harmonic currents. Recommendations for derating factors as a function of the harmonic current distortion level are presented.
Motors in the plant can be adversely impacted by the voltage distortion levels at the various buses. Motors and controls are the primary reasons for the 5% limit in IEEE Std. 519. A more detailed evaluation of the impact of harmonic voltages on motors can be performed by evaluating the individual frequencies involved. A spreadsheet for this purpose is developed and motor heating concerns are identified.

Filter Design and Specification
Harmonic voltage levels determined through both simulation and measurement are evaluated with respect to recommended limits. If harmonic voltage distortion levels are not within acceptable limits the frequency response characteristics of the facility or system can be altered by changing capacitor sizes and/or locations, or be installing harmonic filters. In many instances, harmonic filters are an excellent solution because they can be designed to provide power factor correction at the fundamental frequency and a low impedance path for harmonic currents. Filter components must be designed to withstand both harmonic and fundamental frequency voltages and currents.
A filter design spreadsheet is completed for each filter installation. The information provided can be used to develop specifications for power factor correction/harmonic filter equipment.

Evaluation of Harmonic Voltage and Current Limits (IEEE Std. 519)
Harmonic current and voltage levels determined through both simulation and measurement are evaluated with respect to recommended limits, such as those presented in IEEE Std. 519. If harmonic distortion levels are not within the acceptable limits the impact of harmonic filters is evaluated.
One possible harmonic current limitation is given in Table 10.2 of IEEE Std. 519. Many utilities will require their industrial customers to meet a guideline such as this. This will make the evaluation of power factor correction / harmonic filters even more important.

Basic Electrical Definitions

Definitions:(in alphabetical order)

Accessible - (As applied to wiring methods) Capable of being removed or exposed without damaging the building structure or finish, or not permanently closed in by the structure or finish of the building.
Accessible - (as applied to equipment) Admitting close approach: not guarded by locked doors, elevation, or other effective means. (see Accessible, Readily)
Accessible, Readily - (Readily Accessible) Capable of being reached quickly for operation, renewal, or inspections, without requiring those to whom ready access is requisite to climb over or remove obstacles or to resort to portable ladders,chairs,etc.
Ambient Temperature - The temperature of the air, water, or surrounding earth. Conductor ampacity is corrected for changes in ambient temperature including temperatures below 86°F. The cooling effect can increase the current carrying capacity of the conductor. (Review Section 310-10 of the Electrical Code for more understanding)
Ammeter - An electric meter used to measure current, calibrated in amperes.
Ampacity - The current-carrying capacity of conductors or equipment, expressed in amperes.
Ampere - The basic SI unit measuring the quantity of electricity.
Bonding Jumper - A bare or insulated conductor used to ensure the required electrical conductivity between metal parts required to be electrically connected. Frequently used from a bonding bushing to the service equipment enclosure to provide a path around concentric knockouts in an enclosure wall: also used to bond one raceway to another.
Continuity - The state of being whole, unbroken.
Continuos Load - A load where the maximum current is expected to continue for three hours or more. Rating of the branch circuit protection device shall not be less tan 125% of the continuos load.
Demand Factor - For an electrical system or feeder circuit, this is a ratio of the amount of connected load (in kva or amperes) that will be operating at the same time to the total amount of connected load on the circuit. An 80% demand factor, for instance, indicates that only 80% of the connected load on a circuit will ever be operating at the same time. Conductor capacity can be based on that amount of load.
Dustproof - Constructed or protected so that dust will not interfere with its successful operation.
Dusttight - Constructed so that dust will not enter the enclosing case under specified test conditions.
Duty, continuos - A service requirement that demands operation at a substantially constant load for an indefinitely long time.
Duty, intermittent - A service requirement that demands operation for alternate intervals of load and no load, load and rest, or load, no load, and rest.
Duty, periodic - A type of intermittent duty in which the load conditions regularly reoccur.
Duty, short time - A requirement of service that demands operations at a substantially constant load for a short and definitely specified time.
Duty, varying - A requirement of of service that demands operation at loads, and for intervals of time, both of which may be subject to wide variation.
Explosionproof - Designed and constructed to withstand and internal explosion without creating an external explosion or fire.
Feeder - A circuit, such as conductors in conduit or a busway run, which carries a large block of power from the service equipment to a sub-feeder panel or a branch circuit panel or to some point at which the block power is broken into smaller circuits.
Ground - A large conducting body (as the earth) used as a common return for an electric circuit and as an arbitrary zero of potential.
Grounded, effectively - Intentionally connected to earth through a ground connection or connections of sufficiently low impedance and having sufficient current-carrying capacity to prevent the buildup of voltages that may result in undue hazards to connect equipment or to persons.
Grounded Conductor - A system or circuit conductor that is intentionally grounded, usually gray or white in color.
Grounding Conductor - A conductor used to connect metal equipment enclosures and/or the system grounded conductor to a grounding electrode, such as the ground wire run to the water pipe at a service; also may be a bare or insulated conductor used to ground motor frames, panel boxes, and other metal equipment enclosures used throughout electrical systems. In most conduit systems, the conduit is used as the ground conductor.
Grounding Equipment Conductor - The conductor used to connect the noncurrent-carrying metal parts of equipment, raceways, and other enclosures to the system grounded conductor, the grounding electrode conductor, or both, of the circuit at the service equipment or at the source of a separately derived system.
Grounding Electrode - The conductor used to connect the grounding electrode to the equipment grounding conductor, to the grounded conductor, or to both, of the circuit at the service equipment or at the source of a separately derived system.
Ground Fault Circuit Interrupter - A device intended for the protection of personal that functions to de-energize a circuit or portion thereof within an established period of time when a current to ground exceeds some predetermined value that is less than required to operate the overcurrent protection device of the supply circuit.
Ground Fault Protection of Equipment - A system intended to provide protection of equipment from damaging line to ground fault currents by operating to cause a disconnecting means to open all ungrounded conductors of the faulted circuit. This protection is provided at current levels less than those required to protect conductors from damage through the operations of a supply circuit overcurrent device.
In Sight From - (within sight from, within sight) Where this Code specifies that one equipment shall be "in sight from", "within sight from" or m"within sight", etc. of another equipment, the specified equipment is to be visible and not more that 50´ distant from the other
Interrupter Rating - The highest current at rated voltage that a device is intended to interrupt under standard test conditions.
Labeled - Items to which a label, trademark, or other identifying mark of nationally recognized testing labs has been attached to indentify the items as having been tested and meeting appropriate standards.
Listed - Equipment or materials included in a list published by an organization acceptable to the authority having jurisdiction and concerned with product evaluation, that maintains periodic inspection of production of listed equipment or materials, and whose listing states either that the equipment or material meets appropriate designated standards or has been tested and found suitable for use in specified manner.
Location, damp - A location subject to moderate amount of moisture such as some basements, barns, cold storage, warehouse and the like.
Location, dry - A location not normally subject to dampness or wetness: a location classified as dry may be temporarily subject to dampness or wetness, as in case of a building under construction.
Location, wet - A location subject to saturation with water or other liquids.
Megger - A test instrument fpr measuring the insulation resistance of conductors and other electrical equipment; specifically, a megaohm (million ohms) meter; this is a regiestered trade mark of the James Biddle Co.
Megaohm - A unit of electrical resistamce equal to one million ohms.
Megaohmmeter - An instrument for measuring extremely high resistance.
Noninductive Circuit - A circuit in which the magnetic effect of the current flowing has been reduced by one several methods to a minimum or to zero.
Nonlinear Load - A load where the wave shape of the steady state current does not follow the wave shape of the applied voltage.
Ohm - The derived SI unit for electrical resistance or impedance; one ohm equals one volt per am-pere.
Ohmmeter - an instrument for measuring resistance in ohms. Take a look at this diagram to see how an ohmeter is used to check a small control transformer. The ohmmeter's pointer deflection is controlled by the amount of battery current passing through the moving coil. Before measuring the resistance of an unknown resistor or electrical circuit, the ohmmeter must first be calibrated. If the value of resistance to be measured can be estimated within reasonable limits, a range selected that will give approximately half-scale deflection when the resistance is inserted between the probes. If the resistance is unknown, the selector switch is set on the highest scale. Whatever range is selected, the meter must be calibrated to read zero before the unknown resistance is measured.

Overcurrent - Any current in excess of the rated current of equipment or the ampacity of a conductor. It may result from overload, short circuit or ground fault.
Overload - Load greater than the load for which the system or mechanism was intended. A fault, such as a short circuit or ground fault, is not an overload.
Panelboard - A single panel or group of panel units designed for assembly in the form of a single panel: includes buses and may come with or without switches and/or automatic overcurrent protective devices for the control of light, heat, or power circuits of individual as well as aggregate capacity. It is designed to be placed in a cabinet or cutout box that is in or against a wall or partition and is accessible only from the front.
Plenum - Chamber or space forming a part of an air conditioning system
Rainproof - So constructed, projected, or treated as to prevent rain from interfering with the successful operation of the apparatus under specified test conditions.
Raintight - So constructed or protected that exposure to a beating rain will not result in the entrance of water.
Separately Derived System - A premises wiring system whose power is derived from a battery, a solar photovoltaic system, or from a generator, transformer, or converter windings, and that has no direct electrical connection, including solidly connected grounded circuit conductor, to supply conductors originating in another system.
Service Drop - Run of cables from the power company's aerial power lines to the point of connection to a customer's premises.
Service Conductors - The supply conductors that extend from the street main or transformers to the service equipment of the premises being supplied
Service Entrance Conductors - (Overhead) The service conductors between the terminals of the service equipment and a point usually outside the building, clear of building walls, where joined by tap or splice to the service drop.
Service Entrance Conductors - (Underground) The service conductors between the terminals of the service equipment and the point of connection to the service lateral.
Service Equipment - The necessary equipment, usually consisting of a circuit breaker or switch and fuses and their accessories, located near the point entrance of supply conductors to a building and intended to constitute the main control and cutoff means for the supply to the building.
Service Lateral - The underground service conductors between the street main, including any risers at a pole or other structure or from transformers, and the first point of connection to the service-entrance conductors in a terminal box, meter, or other enclosure with adequate space, inside or outside the building wall. Where there is no terminal box, meter, or other enclosure with adequate space, the point of connection is the entrance point of the service conductors into the building.
Service Point - The point of connection between the facilities of the serving utility and the premises wiring.
Switchboard - A large single panel, frame, or assembly of panels having switches, overcurrent, and other protective devices, buses, and usually instruments mounted on the face or back or both. Switchboards are generally accessible from the rear and from the front and are not intended to be installed in cabinets.
Switch, general use - A switch intended for use in general distribution and branch circuits. It is rated in amperes and is capable of interrupting its rated voltage.
Switch, general-use snap - A type of general-use switch so constructed that it can be installed in flush device boxes or on outlet covers, or otherwise used in conjunction with wiring systems recognized by the National Electric Code.
Switch, isolating - A switch intended for isolating an electrical circuit from the source of power. It has no interrupting rating and is intended to be operated only after the circuit has been opened by some other means.
Switch, knife - A switch in which the circuit is closed by a moving blade engaging contact clips.
Switch, motor-circuit - A switch, rated in horsepower, capable of interrupting the maximum operating overload current of a motor of the same horsepower rating as the switch at the rated voltage.
Switch, transfer - A transfer switch is an automatic or nonautomatic device for transferring one or more load conductor connections from one power source to another.
Switch-Leg - That part of a circuit run from a lighting outlet box where a luminaire or lampholder is installed down to an outlet box that contains the wall switch that turns the light or other load on or off: it is a control leg of the branch circuit.
Voltage Drop - The loss of voltage between the input to a device and the output from a device due to the internal impedance or resistance of the device. In all electrical systems, the conductors should be sized so that the voltage drop never exceeds 3% for power, heating, and lighting loads or combinations of these. Furthermore, the maximum total voltage drop for conductors for feeders and branch circuits combined should never exceed 5%.
Watertight - So constructed that water/moisture will not enter the enclosure under specified test conditions.
Weatherproof - So constructed or protected that exposure to the weather will not interfere with successful operation.