Underground power is not always practical
Have you ever wondered why some neighborhoods or developments have underground electric service instead of the standard overhead power supplied by lines on poles? There are pros and cons to both types of installations. Ultimately, owners — not PEC — make the decision to pay for underground lines.
Currently, about 72% of our primary power lines are overhead and 28% is underground. Several key factors play into the type of lines used in neighborhoods and developments. PEC’s standard installation is to use overhead lines since these costs are generally paid by all members.
Underground lines require substantially more infrastructure and equipment than overhead lines. If a subdivision, for example, wants underground service, the developer will have to dig a trench and install conduit for the cables to be installed in. Connecting service will also require pad-mounted transformers, enclosures, and switchgears. These are more expensive to install than their overhead counterparts and the costs are incurred by the owner.
Additionally, underground primary cables are costlier since they are constructed with insulation, shielding, and a protective jacket. As a result, building underground service is typically several times more expensive than overhead.
In areas with difficult terrain, the cost of putting in the required infrastructure can drive the price even higher. If cost is the biggest factor in the decision, most owners will opt for overhead service.
In areas that prioritize aesthetics over cost, underground service can be appealing. Without the need for power poles, underground service helps preserve unobstructed views, reducing the amount of power equipment in sight. However, underground service still requires aboveground equipment and ongoing maintenance.
For example, every home must be serviced by a pad-mounted transformer. These green metal boxes require 10 feet of space in front and 5 feet on all sides to allow our crews safe and efficient access in the event of an outage. This limits the ability to hide the boxes with plants and landscaping, but they’re generally considered less unsightly than overhead lines. One pad-mounted transformer can service up to eight homes. If looks are the main consideration, most developers will choose to install underground service.
Overhead and underground lines each pose their own safety risks. Overhead lines are not insulated, and therefore must never be touched directly or with other objects like ladders. Always keep at least 10 feet of distance between you and the nearest power line.
Never climb near poles or other power equipment, and do not trim trees near lines yourself. If you see trees growing near our lines and facilities, request tree-care service online or call us at 888-554-4732, Monday through Friday, between 8 a.m. and 6 p.m. A service order will be issued, and a PEC utility forester will contact you and send a crew to safely clear the vegetation.
Always call 811 before you dig, even if you don’t think underground power lines are in your area — it’s the law, and it could save your life. Even if there are no power lines, other important and potentially hazardous utilities could be buried. High-voltage electricity flows through pad-mounted transformers, so PEC has created a list of tips to protect your family, our employees, and your electric service. See them here.
Typically, outages are easier for our crews to diagnose and repair on overhead lines. In many cases, PEC lineworkers can work on overhead lines while they are “hot,” or actively conducting electricity. This means more members can be kept online during repairs and maintenance. Underground service requires the line be deenergized before lineworkers can begin restoration work.
On the other hand, underground lines are significantly less likely to be impacted by common causes of outages such as lightning strikes, fallen trees, and animal interference.
Ultimately, there is no significant difference in reliability between overhead and underground lines. Owners make these decisions based on cost or aesthetics. Regardless, PEC’s crews in blue are ready to ensure members get safe and reliable electricity to their homes or businesses.