Safe Generators in Blackouts

On Tuesday, 4 June 2024, a fault on the 275 kV Linggau-Lahat high-voltage transmission line cut power across much of southern Sumatra. PLN said 4.3 million customers in South Sumatra, Jambi, Bengkulu and Bangka Belitung were affected. On 5 June, supply in South Sumatra had reached only 74 percent, Bengkulu 80 percent and Lampung 60 percent, while the cause of the damage was still being traced (Putra, 2024b). According to PLN, the fault occurred at 11.00 WIB, and the loss of a heavily loaded transmission line tripped power plants automatically, so restarting them, especially coal-fired steam plants, took time (Uly, 2024).

Two things happened on the ground at the same time. In Bandar Lampung, residents bought up 1,500 to 3,000 watt generators because supply was still unstable, and several shops ran out of stock (Jaya, 2024). In Palembang, residents reported voltage reaching 250 volts after power returned, which tripped their meters again and again (Putra, 2024a). This article sets out a simple method for workplaces to run generators and take back grid supply without adding new risks.

The Core Idea

A large outage creates two risky periods. The first is while generators run: carbon monoxide (CO) from exhaust, fire from fuel, and electric shock from makeshift connections. The second is when grid supply returns: voltage can swing, and equipment still connected to a generator can meet the incoming PLN supply.

The strongest data on the first period comes from a systematic review of 28 articles covering the United States from 1991 to 2009. It found 1,888 disaster-related CO poisoning cases, including 75 deaths. Generators were the exposure source in 83 percent of fatal and 54 percent of non-fatal cases, and 67 percent of the generator deaths involved a generator placed indoors. Nearly 89 percent of deaths occurred within 3 days of the disaster's onset (Iqbal et al., 2012).

In Indonesia the legal basis is Minister of Manpower Regulation No. 12 of 2015 on electrical occupational safety and health in the workplace. Employers and managers must implement electrical OHS (Article 2), covering generation through to utilisation of electricity above 50 volts AC (Article 4). Companies with more than 200 kVA of generating capacity must have an electrical OHS expert (Article 7), and inspection and testing are required at installation, use and modification (Article 9) (Kementerian Ketenagakerjaan Republik Indonesia [Kemnaker], 2015).

Five Practical Steps

The steps below are our synthesis of the regulation and evidence above, not a procedure taken from a single standard.

• Map critical loads and generator capacity. Decide which loads must stay on (pumps, emergency lighting, alarms, servers) and make sure the generator can carry them without overload. Company generators above 200 kVA fall within the requirement for an electrical OHS expert (Kemnaker, 2015).
• Connect only through a transfer switch. A generator plugged straight into a socket or panel without a transfer switch and interlock can feed power back into the network. In our view this is the most underestimated hazard, because line workers and other staff may assume the circuit is dead.
• Place the generator outdoors. Keep it away from doors, windows and air intakes, and fit CO detectors in nearby rooms. The finding that two thirds of generator deaths involved indoor placement makes this a priority (Iqbal et al., 2012).
• Take back grid supply in stages. Disconnect sensitive loads, measure voltage at the main panel, then reconnect loads one by one once the voltage is stable. The 250 volt readings reported in Palembang show why this step matters (Putra, 2024a).
• Inspect and record once things are normal. Emergency hookups and hired generators are modifications to the installation, so they need inspection and testing before being kept as a permanent arrangement (Kemnaker, 2015).

A Worked Example

Consider a cold storage warehouse using a hired generator to keep its freezer rooms running. Under this method, the team places the generator in the yard, connects it to the freezer panel through a transfer switch, and only restarts pumps and compressors once grid voltage has been measured as stable. The example is illustrative, not an actual case from the 4 June outage.

Limits of the Method

The method is meant for low-voltage installations at workplaces, not for work on the PLN network. The CO data come from the United States, with different household and seasonal patterns, so the figures indicate direction rather than estimates for Indonesia. The cause of the 4 June transmission fault had not been announced at the time of writing, so we draw no lessons about the transmission system itself.

Where Nusa Safety Fits

Nusa Safety can help companies assess the readiness of backup power systems, including transfer switches, earthing and protection coordination, through its Electrical System Assessment. The Nusa Safety team also runs electrical safety training, with certified programmes delivered together with licensed PJK3 partners, and develops SOPs and technical guidelines for generator operation and supply restoration.

This article is general information and not legal or professional advice for any specific case.

References

1. Iqbal, S., Clower, J. H., Hernandez, S. A., Damon, S. A., & Yip, F. Y. (2012). A review of disaster-related carbon monoxide poisoning: Surveillance, epidemiology, and opportunities for prevention. American Journal of Public Health, 102(10), 1957-1963. https://doi.org/10.2105/AJPH.2012.300674
2. Jaya, T. P. (2024, June 5). Aliran listrik belum stabil, warga Lampung borong genset [Power still unstable, Lampung residents buy up generators]. Kompas.com. https://regional.kompas.com/read/2024/06/05/175437978/aliran-listrik-belum-stabil-warga-lampung-borong-genset
3. Kementerian Ketenagakerjaan Republik Indonesia. (2015). Peraturan Menteri Ketenagakerjaan Nomor 12 Tahun 2015 tentang Keselamatan dan Kesehatan Kerja Listrik di Tempat Kerja [Minister of Manpower Regulation No. 12 of 2015 on electrical occupational safety and health in the workplace]. Berita Negara Republik Indonesia Tahun 2015 Nomor 540. https://jdih.kemnaker.go.id/peraturan/detail/610/peraturan-menteri-nomor-12-tahun-2015
4. Putra, A. Y. K. (2024a, June 5). Aliran listrik di Palembang belum stabil, warga mengeluh elektronik tak bisa digunakan [Power in Palembang still unstable, residents say appliances cannot be used]. Kompas.com. https://regional.kompas.com/read/2024/06/05/114426778/aliran-listrik-di-palembang-belum-stabil-warga-mengeluh-elektronik-tak-bisa
5. Putra, A. Y. K. (2024b, June 5). 4,3 juta pelanggan PLN di Sumbagsel terdampak mati listrik [4.3 million PLN customers in southern Sumatra affected by the outage]. Kompas.com. https://regional.kompas.com/read/2024/06/05/161725378/43-juta-pelanggan-pln-di-sumbagsel-terdampak-mati-listrik
6. Uly, Y. A. (2024, June 5). Listrik Sumsel, Palembang-Bengkulu padam, PLN: Pemulihan secara bertahap [Power out in South Sumatra, Palembang and Bengkulu; PLN says restoration is gradual]. Kompas.com. https://money.kompas.com/read/2024/06/05/140448126/listrik-sumsel-palembang-bengkulu-padam-pln-pemulihan-secara-bertahap