Power cabling

1.1 Install Physical Hardware

📘CompTIA Server+ (SK0-005)

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Power is critical in IT environments. Servers, storage devices, networking hardware, and other data center equipment all rely on reliable, safe, and properly managed power. The Power Cabling section of the exam focuses on how to supply, protect, and manage electrical power for IT hardware.

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1. Redundant Power

Redundancy in power ensures that your IT equipment keeps running even if one power source fails. This is vital for servers, network devices, and storage systems because downtime can be costly.

Key Concepts:

1. Uninterruptible Power Supply (UPS)
   • A UPS provides backup power in case of power outages.
   • It also stabilizes voltage (protects against surges and brownouts).
   • Types:
     • Standby (Offline) UPS: Powers equipment when mains fail. Simple and cost-effective.
     • Line-interactive UPS: Adjusts for small voltage fluctuations without switching to battery.
     • Online (Double-conversion) UPS: Constantly converts power, providing the cleanest and most stable power.
   IT example: A server rack might have an online UPS that powers all servers and network switches to avoid downtime during blackouts.
2. Separate Circuits / Providers
   • Critical systems often connect to two separate power sources from different circuits or utility providers.
   • If one source fails, the other continues to provide power.
   IT example: A data center may have servers connected to Power Distribution Unit A (PDU A) and PDU B, each connected to a separate utility line.

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2. Power Connector Types

Servers and IT hardware use different connectors depending on voltage, device type, and country standards. Knowing the common types is important for proper installation.

Common Connectors in IT:

1. C13/C14 (IEC)
   • C13 = connector on the device (server, switch, monitor).
   • C14 = connector on the power cord (from PDU or UPS).
   • Standard in most racks and servers.
2. C19/C20 (IEC)
   • Used for high-power devices, like large servers or storage arrays.
3. NEMA Connectors (North America)
   • NEMA 5-15: Standard 120V household plug (rare in enterprise servers).
   • NEMA 5-20 or 6-20: Higher power devices.
4. Server Redundant Power Supplies
   • Some servers have dual power supplies, often with C13/C14 or C19/C20.
   • Connect each supply to separate PDUs for redundancy.

Tip: Always check the power rating of devices and connectors to avoid overloads.

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3. Cable Management

Proper cable management ensures safety, airflow, and easy maintenance in IT environments.

Best Practices:

1. Organize Power Cables Separately
   • Keep power cables away from data/network cables to reduce interference (EMI).
2. Use Cable Trays and Labels
   • Label each cable at both ends.
   • Use Velcro straps or cable ties (not too tight) to bundle cables.
3. Maintain Airflow
   • Avoid blocking rack ventilation with messy cables.
   • Good airflow helps prevent overheating.
4. Allow Easy Access for Maintenance
   • Cables should be long enough to replace or move devices without disconnecting everything.

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Summary Table – Key Points for the Exam

Topic	Key Points	IT Example
Redundant Power	UPS, dual power sources, separate circuits	Server racks powered by UPS & separate PDUs
UPS Types	Standby, Line-interactive, Online	Online UPS stabilizing power for critical servers
Power Connectors	C13/C14, C19/C20, NEMA types	Dual power supply server connected to separate PDUs
Cable Management	Separate power/data, label cables, maintain airflow	Velcro-bundled cables in server racks

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✅ Exam Tips:

1. Know UPS types and their purposes.
2. Understand redundancy methods: dual PDUs, separate circuits.
3. Recognize common connector types and their uses.
4. Be able to explain why cable management matters for airflow, safety, and maintenance.