Data centers are ideal markets for the electrical contractor because they have a lot of communications cabling and require vast numbers of power cables for the digital electronics and air conditioning. How familiar are you with data centers? The correct answers and explanations are in red.

1. Data centers are facilities that store and distribute data for ________.
A. The Internet
B. Big companies
C. The government
D. All of the above

Data centers are the storage for Internet data, including web pages, video and programs and data for cloud computing.

2. ________ are very fast computers optimized for finding and moving data.
A. PCs
B. Servers
C. Supercomputers
D. Clients

The computers that find and transfer the data are called servers.

3. Data centers are connected to the Internet by ________ cables.
A. Twisted-pair
B. Coaxial
C. Fiber optic
D. No cables at all. They are connected wirelessly.

The Internet runs on singlemode fiber, so the connection to the Internet is on fiber.

4. Most data centers will contain a mix of fiber, coax and unshielded twisted-pair (UTP) cabling.

Fiber is used for external connections to the Internet and longer links inside the data center, Cat 6A UTP can be used for medium length links, but has higher power consumption and CX-4 is based on coax.

5. Due to the speed requirements of data center connections, up to 10 gigabits per second, ________ and ________ are the preferred multimode optical fibers. (Choose two of the following.)
A. OM1
B. OM2
C. OM3
D. OM4

OM3 and OM4 laser-rated fibers offer the highest performance for links of 10-100 gigabits per second.

6. If UTP copper is used in a data center, ________ is needed to ensure proper operation at 10 gigabits per second.
A. Category 5
B. Category 5e
C. Category 6
D. Category 6a

Of all the UTP rated cables, only Cat 6A is rated for use with 10 gigabit links.

7. A copper alternative to UTP cable, called ________, is designed for short links of up to 10 m (33 feet).
A. RG-58
C. CX-4
D. Channel

CX-4, or 10Gbase-CX4 is a parallel coax link for short connections.

8. In order to prevent crosstalk, Cat 6a cables should not be neatly bundled.

Neatly bundled Cat 6 cables may suffer alien crosstalk, where crosstalk occurs between the same pair in two different cables.

9. The actual layout of power and data cables in a data center has to be coordinated with the layout of equipment racks because ________ of the equipment is quite sophisticated.
A. Placement
B. Spacing
C. Cooling
D. Repairing

Cables and equipment in data centers are arranged to maximize cooling to reduce AC costs.

10. Generally, data centers are kept much cooler than regular offices to ensure proper temperatures for all the equipment, so air conditioning ________.
A. Typically uses as much power as the equipment
B. Has to be carefully designed to provide even cooling to all equipment
C. Must be designed carefully to minimize power consumption
D. All of the above

All true. Power is a big issue for data centers!

HAYES is a VDV writer and educator and the president of The Fiber Optic Association. Find him at