AutoQuiz: What is the Recommended Limit for the Length of an Ethernet Cable Segment?

AutoQuiz is edited by Joel Don, ISA's social media community manager.

Today's automation industry quiz question comes from the ISA Certified Automation Professional certification program.  ISA CAP certification provides a non-biased, third-party, objective assessment and confirmation of an automation professional's skills. The CAP exam is focused on direction, definition, design, development/application, deployment, documentation, and support of systems, software, and equipment used in control systems, manufacturing information systems, systems integration, and operational consulting. Click this link for information about the CAP program. This question is from the CAP study guide, Domain II.

What is the recommended limitation in meters for the length of a Fast Ethernet (100 megabits per second) segment on twisted pair cable?

a) 10
b) 100
c) 300
d) 350
e) none of the above

Because of the high speed of Fast Ethernet, the use of twisted pair cable is limited to 100 meters (328 feet). Ten meters would limit installations unnecessarily. Three hundred meters and 350 meters would exceed recommendations substantially, resulting, potentially, in signal errors.

The correct answer is B, 100 meters.