Common Causes of Power Outage
Power outages occur for many reasons and can last from a few seconds to hours or longer.
Below are some examples of the most common causes of power outages in New Brunswick.
Most power outages are caused by severe weather – high winds, lightning, freezing rain and snow, rain or flooding. During a storm power poles are vulnerable to lightning strikes while strong winds can snap off tree branches and down power lines. Freezing rain or snow can build up on equipment causing damage.
New Brunswick has the highest percentage of tree cover of any electrical jurisdiction in North America. This means we invest in long-term, preventative maintenance to ensure NB Power can deliver electricity safely and reliably to customers. Areas densely populated with trees are more likely to have power outages. When a tree comes into contact with a power line, either due to bad weather or growth, circuit breakers or other protective equipment is designed to cut off the power until crews remove the tree and reset the equipment.
Wildlife such as squirrels, birds and raccoons are responsible for numerous outages in New Brunswick. When they come into contact with equipment in a substation for example, this may result in a service interruption.
Although our equipment is regularly maintained and updated, problems can occasionally occur. From time-to-time, cables, connectors, transformers, switches and many other types of equipment require replacement and can trigger a power interruption.
Vehicles that accidentally hit and damage power equipment can disrupt the power supply.
Occasionally, service interruptions are necessary in order to allow our crews to safely conduct maintenance or repair work. We try to schedule these repairs at the least inconvenient times for you and keep them to a minimum. Whenever possible, we provide you with prior notice before we interrupt service.
On occasion, NB Power customers will experience power interruptions due to vandalism to electrical equipment. Vandalism to electrical equipment jeopardizes the individuals’ safety, the public’s safety as well as the safety of NB Power employees. Damage to NB Power properties can lead to loss of electricity for entire communities including essential services such as hospitals and 911 services.
Severe weather conditions in New Brunswick that adversely affect power distribution can be generally categorized into any combination of rain, freezing rain, snow and high winds.
The following Gallery of the 2013 Ice Storm illustrates the effect of weather on power lines.
Rain can cause havoc on insulation of high voltage lines by reducing the insulation properties of porcelain bushings, switches, and the pin insulators that attach the lines to the poles.
Insulators play an important role in keeping the flow of electricity moving and not shorting out on structures. Any crack or breakage of an insulator allows water, mostly in the form of rain to cause a failure. This failure interrupts power by blowing a fuse, not unlike the ones found in our fuse panel in our homes.
Freezing rain poses a special concern with the electrical system where it tends to stick and build on all components. This may cause the same issues as rain in that it may compromise insulation.
Freezing rain can also build on conductors and sometimes causes them to form a heavy ice shell many times the diameter of the conductor and in some cases, when the weight exceeds the design strength of the wire, it breaks and falls to the ground resulting in an interruption.
Freezing rain also interacts with tree limbs that may be in close proximity, weighing down and contacting the conductor which in turn causes a short circuit, eventually resulting in an interruption.
Dry snow normally does not cause much concern with the electrical system. Wet snow, however, poses some of the same concerns that freezing rain does in that there is potential for insulation breakdown due to moisture or snow loading on tree limbs causing conductor contact and eventual power interruptions.
High Winds (90+ kilometres per hour)
These higher strength winds have the potential of breaking trees and tree limbs causing them to fall over the lines. They can also cause a conductor fault. In this instance, the customer may see the lights go out and return within seconds as our breaker protection momentarily clears the fault and recloses. If the fault is gone the power remains on. This type of momentary interruption may also occur when a tree limb falls onto the line and then falls off.
High winds also have the potential of creating salt spray conditions in our coastal areas that can cause some of our equipment to fail.
Moderate Winds (60 to 90 kilometres per hour)
When drastic temperature variation is present, lightning may result. Power interruptions can result when lightning contacts our structure or power lines. Lightning arrestors are placed at strategic places on the lines to protect critical switching and voltage regulation components.
Moderate winds also have the ability to cause conductor fault. In this instance, the customer may see the lights go out and return within seconds as our breaker protection momentarily clears the fault and recloses. If the fault is gone the power remains on. This type of momentary interruption may also occur when a tree limb falls onto the line and then falls off.
These lower strength winds typically create outages when the leaves are still present on trees. They act as a sail that in turn can increase the stresses on tree limbs and in turn contribute to the damage to the tree and our equipment. They have the potential of breaking trees and tree limbs causing them to fall over the lines.
Often with lightning storms there are periods of severe winds for brief periods that can also cause problems for our lines.
During the winter months severe cold is a fact of life in New Brunswick. Common failures associated with severe cold are frost breaks on conductors, system overload, and insulator failures.
During these cold snaps when the power goes out, our first reaction may be to turn heaters and lights on in anticipation of our power being restored. This can sometimes extend the outage because the fusing may be unable to take the stress of the high demand for power during the cold load pickup. Customers should wait for the power to return and slowly add their power requirements a bit at a time.