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Essential Information About Rolling Blackouts (Load Shedding)

Satyajeet Vispute Jun 30, 2019
Rolling blackouts are a precautionary counter-measure against excessive power demand. Here, we shall find out what rolling blackouts actually mean, what causes their need, and how are they implemented.

Rolling Blackouts in California

In the early 2000s, California faced an electricity crisis, which resulted in frequent blackouts, said to be triggered by the hot summer temperatures that led to a huge surge in the use of air conditioners. However, in 2004, taped conversations of Enron traders revealed that they had been manipulating the electric supply to raise energy prices.

What Does a Rolling Blackout Mean?

A rolling blackout is the term used to describe an intentional power cut that is made to take place for the purpose of load shedding, that is, for reducing the load on the electricity generation system and grid.
These are employed when the demand for power surpasses the supplying capacity of the electricity network.

Rolling blackouts are used by electric utility companies as a last resort for preventing a total blackout situation, wherein the electric supply to the entire distribution region stops.
Depending upon the requirements, rolling blackouts may affect a small part or the electric network, or even entire cities and states.


Rolling Blackouts are initiated when insufficient power generation due to production issues, shortage of fuel, excessive demand, and other similar reasons. Caused by inadequate power transmission as faulty or antiquated distribution systems.

Mechanism of Working

In electricity generation and distribution stations, independent monitors are used, which continuously assess the power being supplied and drawn to and from the grid. Typically, when one of these monitors detects a constant spike in the power demand, or if the energy supply dips, it alerts the operators.
The station issues a notice to the public to reduce power consumption to avoid rolling blackouts.

This supply-demand imbalance continues, either a brownout (drop in voltage) or a rolling blackout is initiated. 'Rolling' is the power delivery to different regions cut at different, non-overlapping time internals, ensuring that a mass outage doesn't occur.
The following is how a rolling blackout typically works:

The distribution region is divided into a number of outage blocks, and a priority level is assigned to each one. The high priority blocks are least affected, as a power outage usually doesn't take place there. They include hospitals, police stations, and other such important installations.
In the low to moderate blocks, a power outage occurs at different time intervals. Importantly, it is ensured that the blocks which will be experiencing power outages at the same time interval are widely separated from each other, so that a large community doesn't experience a complete blackout.
This is done mainly for reasons of safety, as according to statistics, most common crimes such as looting, robbery, etc., usually take place in the dark.

Distribution and Frequency

In many underdeveloped or developing countries, such as Nepal, Pakistan, Philippines, India, South Africa, etc., rolling blackouts or load shedding is a frequent and even daily occurrence.

Depending upon the region, these may last for an hour or even for 8 hours at a stretch.
They are the result of shortage of funds for electricity generation, and/or the use of outdated and/or mismanaged power infrastructure.

This occurrence is usually not seen in developed countries, where funding is sufficient, the demand forecast is accurately, and networks are well managed.
Also, in these regions, power failure is considered as a lack of planning, which can adversely affect the political mileage of the government. Hence, every effort is taken to keep them from happening.

However, even so, unexpected events such as storms, floods, hurricanes, etc., may necessitate a rolling blackout in developed regions as well.
Man-made faults and equipment failure may also lead to the same. Importantly, as far as possible, prior warnings are issued to the public so that the people can work around these events.

Safety Considerations

One should ensure that all sensitive electric equipment is turned off, and preferably unplugged when the power supply is cut.
When the power returns, one can turn the appliances back on, but should try to restrain from using high-power-consuming devices, such as air conditioners, immediately. After some time, if the power continues to remain constant, then one can resume the use of all these devices.
Since rolling blackouts are intentionally created occurrences, the chances of them causing damage to electric equipment in homes, or the power lines and grids as a whole, are relatively slim. Yet, it is advisable to take the same precautions that one would take in case of an unscheduled power outage.
Thus, rolling blackouts are deliberately induced power cuts that are meant to protect the distribution region from a complete blackout situation. In most cases, they are well managed and designed, so that they have minimum impact on the consumers.