Free Practice Questions for Exin CDCS Exam

ANSI/TIA-942 specifies minimum floor live load capacities based on Rated levels:

Rated-1/2: ~7.2–8.4 kPa

Rated-3: 12 kPa

Rated-4: 15 kPa

These values ensure raised floors can support racks, cabling trays, cooling units, and maintenance loads without structural compromise. For Rated-3, concurrent maintainability requires higher floor robustness to handle additional infrastructure.

Therefore, the correct requirement is 12 kPa.

A hypoxic-based fire suppression system works by reducing the oxygen level in a room to below what is necessary to sustain combustion. This makes it effective in fire prevention, but it is not suitable for continuous occupancy by personnel. Low oxygen levels can cause discomfort or even health risks for people spending extended periods in the space. Therefore, these systems are typically deployed in areas where continuous human occupancy is not required, such as storage rooms or data halls with limited personnel access.

Detailed Explanation:

Hypoxic fire suppression systems lower oxygen levels to around 15-16%, which is safe for short periods but not sustainable for continuous occupancy without risk to health. Data center environments where staff need to spend long periods monitoring and maintaining equipment would need alternative systems, like gas-based suppression that allows for safe evacuation rather than oxygen reduction.

EPI Data Center Specialist References:

The EPI Data Center Specialist curriculum emphasizes that fire suppression systems must be chosen based on occupancy requirements. Hypoxic systems are specifically noted as unsuitable for spaces requiring continuous human presence due to the low oxygen environment they create.

The formula used to calculate the gas content differs significantly between halocarbon and inert-based fire suppression systems. Halocarbon systems function by absorbing heat, while inert systems work by reducing oxygen levels. Due to these differences in fire suppression mechanisms, distinct formulas are applied, factoring in the specific properties of each gas type and the required concentration levels.

Detailed Explanation:

Halocarbon systems like FM200 require a formula that accounts for the concentration needed for cooling, while inert gases like nitrogen or argon need a formula that calculates the volume based on oxygen displacement. As the design concentration and characteristics of these gases differ, it’s essential to use the correct formula specific to the gas type.

EPI Data Center Specialist References:

EPI recommends consulting the specific design requirements and formulas provided by each gas manufacturer when switching fire suppression systems to ensure the correct amount of gas is deployed for effective fire suppression.

According to ANSI/TIA-942 standards, the overall data center rating is determined by the lowest rating among all evaluated categories. Therefore, if a data center is rated 2 in architectural, despite being rated higher in mechanical and electrical, the overall rating is Rated-2. This approach ensures that all aspects meet a minimum standard and prevents a higher rating if any critical area does not comply.

Detailed Explanation:

ANSI/TIA-942 evaluates data centers across several areas, including mechanical, electrical, architectural, and telecommunications. The overall rating reflects the lowest rated category, ensuring that no aspect of the data center’s design or operation falls below the specified level. Thus, in this case, the architectural rating of 2 dictates the final rating, ensuring a comprehensive and balanced assessment of reliability and resilience across all aspects.

EPI Data Center Specialist References:

EPI Data Center Specialist training aligns with ANSI/TIA-942, stating that the final rating must reflect the lowest score to ensure comprehensive reliability across all critical infrastructure categories. This avoids overstating the data center's resilience and ensures uniform standards across areas.

Forced-entry ratings use defined attack tools and durations (time-to-breach) executed by attacker profiles.

ANSI/TIA-942 defines ratings across four areas:

Architectural

Electrical

Mechanical

Telecommunications (network cabling + architecture)

A data center cannot be considered Rated-3 unless all four areas meet the concurrent maintainability criteria. For telecom/networking, this means dual redundant backbone cabling, proper pathways, and separate routes to ensure no single point of failure.

A and B are incorrect because they limit scope to electrical/mechanical or cabling only.

C is incomplete: administration (ANSI/TIA-606) is part of compliance but architecture redundancy is mandatory.

The aisle pitch is the total width of a rack row plus cold aisle plus rack row. For 1.0 m racks on each side with cold aisle containment, ASHRAE and TIA-942 recommend the 7-tile rule (each tile ~0.6 m). This ensures enough width for equipment clearance, airflow distribution, and human access.

5-tile pitch is too narrow, restricting containment effectiveness.

8–10 tiles may be used in some hyperscale layouts but are not standard for 1 m racks.

Thus, the correct design recommendation is the 7 tiles pitch rule.

The amount of FM200 gas required can be calculated using the formula:

Weight of Gas=Net Volume×Design Concentration×S-Factor\text{Weight of Gas} = \text{Net Volume} \times \text{Design Concentration} \times \text{S-Factor}Weight of Gas=Net Volume×Design Concentration×S-Factor

Using metric units:

Net Volume: 2,500 m³

Design Concentration: 7% (or 0.07)

S-Factor: 0.1359

Calculation:

2,500 m3×0.07×0.1359=821.325 kg2,500 \, \text{m}^3 \times 0.07 \times 0.1359 = 821.325 \, \text{kg}2,500m3×0.07×0.1359=821.325kg

Rounded to the closest answer: 820 kg

In imperial units:

Net Volume: 88,287 ft³

S-Factor: 1.885

Calculation:

88,287 ft3×0.07×1.885=1,165.27 lbs88,287 \, \text{ft}^3 \times 0.07 \times 1.885 = 1,165.27 \, \text{lbs}88,287ft3×0.07×1.885=1,165.27lbs

Rounded, this is approximately 1,800 lbs.

EPI Data Center Specialist References:

EPI instructs on using specific formulas and S-factors provided by manufacturers for each gas type, ensuring that calculations reflect the correct concentration for the given room volume.

To reduce Electromagnetic Fields (EMF) emanating from the electrical riser near sensitive IT equipment, three-phase power cabling in a combined cable (such as XLPE) is effective. Combined cabling helps reduce EMF by keeping the conductors tightly packed, which minimizes magnetic fields generated by current flow. Cables like XLPE (cross-linked polyethylene) also offer better insulation, which helps mitigate EMF interference with nearby IT equipment.

Detailed Explanation:

Using a combined three-phase cable reduces EMF because the magnetic fields generated by each phase tend to cancel each other out when in close proximity. This arrangement helps reduce the overall magnetic field strength. In addition, XLPE and similar materials provide good insulation, making them a preferred choice for reducing EMF emissions around sensitive equipment.

EPI Data Center Specialist References:

EPI data center best practices recommend mitigating EMF interference through combined cabling arrangements, especially near areas where sensitive IT equipment is located. Reducing EMF is crucial to maintaining equipment reliability and ensuring compliance with safety standards.

The diagram shows three UPS modules, each 100 kW, connected in parallel to support a 100 kW IT load. That means:

One module (100 kW) can support the load (N).

Two additional modules are installed as redundancy.

This equals N+2 redundancy.

2+N+1 and 2(N+1) imply dual active paths not shown.

N+N+N is not an industry term.

Thus, the correct redundancy level is N+2.