Underground School

Minnesota Municipal Utilities Association, along with our partners at Minnesota Rural Electric Association (MREA), are pleased to offer the 2025 Underground School.

The Underground School features two class options for hands-on training:

• Option 1: Multi-session class - participants will rotate through six different sessions, covering a variety of topics and activities to develop new skills and enrich proficiency.
• Option 2: Advanced class - participants in this class will delve deep into Equipotential Grounding and the Isolation Method through classroom discussion and activities in the field.

NOTE: Members of MREA need to register on their site directly.

What you will learn - general sessions

The general sessions are held on the first and last day of the school. Participants must attend these sessions to receive full credit for course hours.

Tuesday, May 6

Gopher State One Call/Office of Pipeline Safety

Hear from experts on how Gopher State One Call works behind the scenes and recent updates we should know about. Learn about accidents that have caused severe damage, and the costs associated with those.

Friday, May 9

Hurricane Milton recap
We will discuss our mutual aid deployment to Florida for Hurricane Milton, which occurred in October of 2024. Participants will gain an understanding of the process—from the initial request for crews and equipment to safety briefings and restoration efforts in Florida to returning home.

What you will learn - hands-on training

Participants rotate through the following sessions.

Session #1 - Circuit isolation and switching

This session will cover the importance of following switching orders when they are needed to be completed. Instructions on proper steps will be taken to cover the techniques needed to switch and isolate underground equipment. The required procedures and use of tools and equipment will be taught on how to effectively test and ground your work area.

Session #2 - Cable pulling
This session will focus on the proper procedures for pulling wire. Crews will pull in 1/0 wire using state of the art pulling equipment. Participants will be instructed on preparing the site on which the work will take place and identifying the hazards that may be in the area. This class will focus on safety and proper procedures to increase confidence and expand knowledge of the tasks at hand. 

Session #3 - Locating

This session is designed to give individuals a better understanding of locating underground cables. Individuals will be able to try different brands of locators and go through the different techniques used in locating, including using the A-frame locator to locate faulted secondary wires..

Session #4 - Troubleshooting and fault-finding primary cable
In this session, students will be taught how to isolate and restore power on underground primary systems. Proper use of phasing sticks with direct current hi-pot adapters, fault indicators, and thumpers will be demonstrated to help students understand and address the issues related to underground cable faults.

Session #5 - Leaking transformer changeout

This session will cover how to properly change out a leaking transformer. Students will be taught what needs to be done with the contaminated area, as well as materials and tools, and what to do if the oil has polychlorinated biphenyls (PCBs).

Session #6 - 600-amp terminations
This session will help participants gain important knowledge in the process of terminating 500 MCM aluminum wire. Terminations for a riser, splice, and elbows will be taught. Proper tool selection and grounding will also be covered. 

This course will focus on equipotential grounding and the isolation method. Proper testing and grounding is one of the single most important safeguards we have in our industry. It establishes a safe work zone where all conductors are at the same potential. It ensures that even if a circuit becomes energized the lineworker is still protected. Also, utilizing the isolation method for underground construction, will prevent any fault current from entering the worker.

• Discuss changes made to the APPA safety manual regarding equipotential grounding of underground and overhead distribution lines.
• Discuss what the isolation method is and the science behind why equipotential grounding is the safest way to ground.
• Hands-on equipotential grounding dealing with different scenarios in both underground and overhead applications.
• Hands-on using the isolation method on underground distribution cables.

Optional activities

Wednesday, May 7

Sporting clay shoot, golf, or archery
Participants are responsible for any fees associated with these optional activities. For archery, participants need to supply their own bow and arrows.

Thursday, May 8

Lineworker mystery event
This mystery event is open to all lineworkers, from first-year apprentice to the seasoned journeyman. This is a fun event which demonstrates safe work practices and a little speed. The individual with the best time and fewest infractions will be recognized.