Power Restoration and Repairs
What We’re Doing and How Long it Takes
No matter how thoroughly we prepare, power outages happen. Most of the time, they’re caused by elements outside of our control, from violent storms to wayward vehicles or tree branches and even the occasional bird or Mylar party balloon.
We know our service is critical, so TEP teams work as quickly and safely as they can to restore power to our customers. Last year, we achieved 99.9 percent reliability, with typical customers experiencing just 48 minutes without power, on average, over the course of the entire year.
That’s a record we maintained in part because of our preparations to ensure our vast system is as resilient as possible during these extreme weather events. In July 2021, we replaced about 140 damaged poles during a very active month of monsoon storms. But that’s just one-tenth of 1 percent of the more than 110,000 poles we manage in our service territory, along with more than 100 substations.
So why can we fix some power outages in less than 30 minutes when others can take longer?
Restoring power is a complex task that requires significant logistical expertise, highly skilled workers and specialized equipment. These elements must come together in a coordinated cadence to restore the flow of energy through our network of power lines, substations, transformers, relays and circuit breakers.
Here are the six steps we follow when responding to an outage.
1. During extreme weather events, we might field more than 500 calls within a 12-hour period. That means we have to prioritize where we send our first responders. We address 911 calls first, and we often arrive at scenes before fire fighters and police officers. Then come other immediate threats to public safety, like damaged poles and lines impacting roadways or homes, and incidents affecting critical customers such as hospitals.
2. It’s usually not obvious why an outage has occurred, or exactly where the problem might be. Our Troublemen seek to answer those questions by driving out to the affected area and looking for the issue. This can take some time, particularly in remote areas, during harsh weather or if the problem is underground. Customers who witness damage to our system can report it by calling our emergency hotline: (520) 623-3451.
3. Secure the scene. Once we find the problem, our first priority is to address immediate safety issues, such as de-energizing and securing downed power lines and making necessary preparations that allow repairs to proceed safely. For larger problems, this may include erecting barricades and posting guards to keep members of the public out of harm’s way.
4. Isolate the problem. Sometimes, the Troubleman who identifies the problem can resolve it quickly – perhaps by removing a tree branch that has fallen across power lines or replacing a blown fuse. If so, that’s the end of the outage. But if repairs will take longer, we work to isolate the damage from the rest of our local energy grid so that we can begin restoring service before repairs are complete.
5. Our field teams work with system controllers to temporarily reconfigure our grid in ways that route power around the problem, using existing switches and/or installing “jumpers” that create short-term connections. To avoid overloads, we often must restore service step by step rather than all at once. This process can take longer during periods of high energy use, as reconfigured circuits may not have the same capacity as the original configuration. After critical facilities are energized, our process aims to restore power to the largest number of customers in the shortest amount of time. In most cases, we can restore service to all but a handful of customers before proceeding to the next and final step:
6. Repair the Damage. This step sounds simple enough, but it often takes the longest – particularly after a storm that causes damage all over town. We can’t just remove a damaged pole and slide a new one into its place. Even in the best case scenarios, since lives are at stake in the work we do, repairs can take several hours and must follow a meticulous plan.One of the first considerations is labor. In an emergency, our teams work 16-hour shifts, even in punishing conditions, so we need to build in time to recover. Our design team also needs time to evaluate outage impacts and system capabilities.
If we’re digging new holes, we have to get clearance from Emergency Blue Stake to make sure we don’t hit any other underground utility lines. We then gather the right materials and tools for the job, since different equipment is needed depending on the size of the pole and its function. We also have to coordinate with our warehouse and the heavy equipment and transportation teams to deliver poles and other large equipment that won’t fit on our bucket and digging trucks.
Restoration times sometimes change. A seemingly simple repair can become a more complex job if we determine there’s more going on than we initially recognized, and that can delay other jobs if storm damage is widespread.
Replacing each pole requires using a lift to pull it out, filling in the hole and removing all the pole-mounted equipment. The new pole is outfitted with new equipment and set in a new hole dug as much as 16 feet or deeper for stability. During the July storms, there was so much rain that some of the new pole holes were collapsing as they were being dug.
Even then, restoration is not as easy as just flipping a switch. Our teams carefully test to make sure the repair was done correctly and addressed the problems.
In rare cases, we initiate outages ourselves to allow for safe repairs or upgrades. Those planned outages are scheduled during periods of low demand, if possible, and are carefully planned to reduce the scale and length of the outage.
“We know our customers are relying on us to keep the power flowing, and to give them timely, accurate information,” said Cynthia Garcia, Vice President of Energy Delivery. “Restoration is universally complex and can be a changing landscape, and particularly in cases of widespread outages across the community. We appreciate our customers’ patience and want to reassure them we’re working as quickly and safely as we can to bring them back into power.”