What happens to a cellphone tower during load shedding?

When load shedding occurs, a cellphone tower remains fully functional for as long as the batteries last or the back-up generator keeps running. Once power is fully depleted, the tower stops working entirely and, depending on the configuration of nearby towers, may cause a coverage area to black out entirely or for customers to experience intermittent service. Generators run on diesel, which means they can continue to run while being refuelled. Batteries, on the other hand, will last anywhere from four to eight hours before they will need electricity to recharge.

How does this affect the customer and why would they experience intermittent service?

Typically with load shedding, if your nearest cellphone tower with the strongest signal (your primary cell) goes down, you could then be connected through 'signal spillage' from a secondary cell. In this instance, as the customer is on the edge of that cell, network service deteriorates and can result in intermittent service. Naturally if both the primary and neighbouring secondary cells are powerless, there is no signal at all. It is also worth noting that the network service quality will start degrading if more people connect to the sites which are still up – in other words, the number of mobile subscribers would stay the same, but the number of serving sites would be reduced.

Are some Vodacom coverage areas virtually blacked out during load shedding and others not at all?

It depends on how long the back-up power lasts, as the vast majority of our towers have battery or generator back-up power. It is when the period of load shedding exceeds one typical battery charge / deplete cycle that a tower goes off line, and with it, connectivity in that cell coverage area. If the outage lasts long enough for batteries to drain, some areas can be completely blacked out, and others not impacted at all. This is purely a function of the load shedding schedule, and the areas impacted. For example, Sandton may not have any power, while Rosebank may remain unaffected.

As an example, let’s say there are five sites servicing a particular area. When there is a black-out, and they all have battery back-up, they can keep going for a period of time of between four and eight hours, depending on how healthy the batteries still are. All five sites will not go down simultaneously. One might fail after two hours, one might fail after four hours or eight hours. If the grid outage is, for example, ten hours then you’ll have the sites failing from the worst battery life cycle of say two hours to about eight hours maximum.

What impact does load shedding have on batteries in cell phone towers?

Batteries have a limited number of charge / deplete cycles, which means the more often they are called on to work, the shorter their lifespan. With infrequent outages, a battery can last for five years, but with frequent outages due to load shedding this will reduce to one year or two years.

What are the cost implications of load shedding for Vodacom?

Vodacom spends significant amounts on backup power solutions such as diesel generators and batteries to maintain power to our sites. Additional input costs and revenue losses amount to tens of millions of Rands.

What would happen in the event of a national black-out for over twelve hours?

The radios would go down and the network would shut down. Our core facilities would still be up and our generators with huge fuel tanks would kick in but the radio base stations would start going down about eight hours into a black out and you’d have basically no signal. Vodacom’s key sites, such as transmission hub sites, have fixed generators that will keep the key sites up. We also have mobile generators which can be deployed in other key locations.

What is Vodacom doing to mitigate the impact of this situation?

Vodacom would like to assure customers that we have put proactive measures in place to help mitigate the effects of widespread load shedding. For instance, we have deployed additional resources, batteries and generators at numerous sites across the country. We would like to appeal to customers to take note of Eskom’s load shedding schedule to try and plan around areas affected by scheduled outages.

What are Vodacom’s back-up plans if the national Grid falls over?

Vodacom is doing everything it can to mitigate the effects of protracted load shedding which is having a detrimental impact on all mobile network operators. In the event of a national grid collapse, Vodacom can keep its core network up as long as it has access to diesel for its generators. We have plans in place to protect our key sites and continue to make the necessary investments to prepare for and manage the increased severity of load shedding as detailed above. Our core network remains well protected however in a time of crisis this would depend on the availability of fuel.

What impact does protracted Stage 4 load shedding have on your network?

Stage 4 load shedding places additional strain on network operators. A notable complication with Stage 4 load shedding over consecutive days is that batteries don’t get enough time to recharge to full capacity. In addition to this, more areas are down at the same time which affects more sites and we therefore have increased challenges in getting to all of the sites.

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