NERC Vegetation Management 2 — Questions and Answers
Question 1: What is the general voltage threshold above which NERC FAC-003 typically applies to transmission lines?
- 69 kV and above
- 115 kV and above
- 200 kV and above (Correct answer)
- 345 kV and above
Correct answer: 200 kV and above
FAC-003 generally applies to transmission lines operated at 200 kV and above, as well as any lower-voltage lines that the Planning Coordinator designates as critical to bulk electric system reliability.
Question 2: What does the 'imminent threat' provision in NERC FAC-003 authorize Transmission Owners to do?
- Bypass FERC approval to de-energize a line immediately
- Take immediate action to remove vegetation posing an urgent risk to transmission line reliability (Correct answer)
- Issue public safety warnings without state utility commission approval
- Redirect transmission flows around affected lines automatically
Correct answer: Take immediate action to remove vegetation posing an urgent risk to transmission line reliability
The imminent threat provision allows Transmission Owners to respond immediately when vegetation poses an urgent risk of causing an outage, even outside normal scheduled maintenance windows.
Question 3: Which of the following is a mandatory element of a Transmission Owner's vegetation management program under FAC-003?
- A certified arborist permanently on staff
- A real-time remote sensor network monitoring vegetation height
- An annual vegetation work plan identifying areas and methods (Correct answer)
- A GPS-tagged inventory of every tree within the right-of-way
Correct answer: An annual vegetation work plan identifying areas and methods
FAC-003 requires Transmission Owners to create and implement an annual vegetation work plan that identifies the areas where work will be performed and the methods to be used.
Question 4: Under FAC-003, what must a Transmission Owner do if planned vegetation work cannot be completed as scheduled?
- File a formal exemption petition with NERC headquarters
- Document the reason and reschedule the work as soon as practicable (Correct answer)
- Immediately notify FERC and request a compliance extension
- De-energize the affected transmission segment until work is complete
Correct answer: Document the reason and reschedule the work as soon as practicable
When planned vegetation work cannot be performed on schedule, FAC-003 requires the Transmission Owner to document the reason for the delay and complete the work as soon as practicable.
Question 5: What vegetation management approach does NERC FAC-003 support that combines biological, mechanical, and chemical control methods for long-term effectiveness?
- Total Vegetation Elimination (TVE)
- Systematic Encroachment Prevention (SEP)
- Integrated Vegetation Management (IVM) (Correct answer)
- Precision Right-of-Way Control (PRWC)
Correct answer: Integrated Vegetation Management (IVM)
Integrated Vegetation Management (IVM) is the approach endorsed by NERC that uses a combination of biological, mechanical, and chemical methods to manage vegetation cost-effectively and with minimal environmental impact.
Question 6: In transmission right-of-way vegetation management, what is the 'wire zone'?
- The corridor where underground cables must be routed
- The restricted airspace above transmission conductors
- The area directly under and laterally adjacent to conductors where only low-growing compatible vegetation is allowed (Correct answer)
- The buffer strip separating transmission and distribution infrastructure
Correct answer: The area directly under and laterally adjacent to conductors where only low-growing compatible vegetation is allowed
The wire zone is the area directly beneath and adjacent to transmission conductors where vegetation management is most critical, allowing only low-growing species that cannot reach or fall into the conductors.
Question 7: How does increasing altitude affect the Minimum Vegetation Clearance Distance (MVCD) required under FAC-003?
- Higher altitude allows smaller MVCDs because thinner air conducts electricity less easily
- Higher altitude requires larger MVCDs because air at elevation has lower dielectric strength (Correct answer)
- Altitude has no effect on MVCD — only conductor voltage determines the required gap
- MVCD decreases above 5,000 feet due to reduced humidity levels
Correct answer: Higher altitude requires larger MVCDs because air at elevation has lower dielectric strength
At higher elevations, the lower air density reduces the dielectric strength of the air, meaning larger clearance distances are needed to prevent electrical flashover between conductors and vegetation.
NERC Vegetation Management 2
What is the general voltage threshold above which NERC FAC-003 typically applies to transmission lines?