Inspections in Missouri
Ameren Missouri is complying with reliability rules issued by the Missouri Public Service Commission (MoPSC) regarding the inspection of underground facilities.
inspections-main
Improving Reliability
Every day, Ameren Missouri is inspecting our equipment to provide safe and reliable power to 1.2 million customers. We also monitor the electric grid 24/7. Equipment inspections ensure reliable service and allow us to proactively address any possible issues or concerns before they impact customers.
Learn More (PDF)
Equipment Inspections

Ameren Missouri is complying with reliability rules issued by the Missouri Public Service Commission (MoPSC) regarding the inspection of underground facilities.

Under the rules, utilities must visually inspect underground transformers and other pad-mounted equipment once every four years, and open this equipment and perform detailed inspections once every eight years.

How this impacts you - the property owner:

If you receive a letter from Ameren Missouri indicating your pad-mounted equipment will be inspected, please note that some action may be required on your part. We will follow a standard procedure for completing this work:
  • Within a few weeks of the date of the letter, Ameren Missouri representatives will be in your area to inspect our underground facilities. Please prepare for their visit. Check the area around the pad-mounted equipment. Assess what you need to remove to obtain proper clearance. See the illustration above.
  • Keep the area clear - within 10 feet of the equipment access door, and within 30 inches on all other sides of the pad-mounted equipment.
Note: These clearances are required for the proper maintenance and operation of Ameren Missouri's equipment. Inability to maintain or operate our equipment can lead to a lengthy outage for property owners and their neighbors.

Please call 811 before you dig so underground utilities can be marked and identified.

Pad-Mounted Equipment Inspection Types

Ameren Missouri representatives will complete the inspection or equipment testing. If they find any obstructions in the required clearance areas, they may not be able to complete the inspection or testing process. As the property owner, you may be contacted by an Ameren employee to discuss options to remove the obstruction, which will allow us to complete our inspection.

Minor vegetation, bushes and shrubs may be trimmed or removed by Ameren Missouri representatives, in order to complete the inspection, or for operating and maintenance purposes. Ameren Missouri personnel conduct two types of inspections:

Note: Some vegetation, where trimming is required to complete our inspection, may be left for homeowners disposal. For more information, call 800.552.7583.

 

Patrol Inspections

Completed once every four years.
Visual inspection of equipment.
Designed to identify problems or hazards.

Detailed Inspections

Completed once every eight years.
Careful examination of transformer structure.
Transformer is opened, and its condition rated and recorded.
Visual and thorough use of routine diagnostic testing, if needed.
Pad-Mounted Equipment
inspections-pad-mounted
Pad-Mounted Transformer

A transformer is a device that reduces the high level voltage found on Ameren Missouri's distribution system, to the more useable voltage levels found inside homes and businesses.

A pad-mounted transformer is the underground equivalent of the overhead transformer. In residential areas they look like forest green colored boxes. The dimensions are approximately 32" tall x 34" wide x 34" deep. All cables come into the transformer below ground, and all connections are made inside and kept out of view.

Note: All pictures are free of obstructions on all sides, and top of our equipment.

inspections-junction
Junction Box
A junction box is a simple piece of pad-mounted equipment, used for splitting high voltage circuits into multiple directions. As with pad-mounted transformers, junction boxes are forest green in color. Two sizes of junction boxes are used on the Ameren Missouri system. The smaller one is approximately 3' x 2' x 3' (H x W x L), and the larger one is approximately 3' x 2' x 6' (H x W x L). Crews inspect junction box equipment once every four years, and open and test this equipment once every eight years.
inspections-switchgear
Switchgear
Pad-mounted switchgears are used to provide switching points, and fuse protection for Ameren Missouri's underground facilities. As with pad-mounted transformers, switchgears are forest green in color. They are approximately four feet tall, and sit on a 6' x 6' pad. They are more common in commercial and industrial areas, but can be found in some residential areas. Crews inspect switchgear once every four years, and open and test this equipment once every eight years.