The biggest labour union at South Africa’s Eskom demanded a 15% wage increase, as the cash-strapped utility struggles to generate adequate electricity to meet the country’s needs, resulting in daily blackouts.

The National Union of Mineworkers wants the same raise for all workers, along with other increases in allowances for housing and other benefits, it said in a copy of a letter to Eskom seen by Bloomberg.

Wage negotiations at the utility come at a contentious time for Eskom and South Africa. Measures implemented by President Cyril Ramaphosa to end power shortages have included expanding a program to buy renewable energy and creating the post of electricity minister. Those steps haven’t halted outages that have deepened in recent days.

The first round of this year’s wage negotiations will run from April 19-21 in Johannesburg, according to NUM spokesman Livhuwani Mammburu. Eskom didn’t immediately respond to a request for comment.

Solidarity, another labour union at the utility, has also submitted its demand for a pay increase of 3 percentage points above the average inflation rate. Price-growth averaged 6.9% last year and the central bank projects that will slow to 6% for 2023.

Labour unions agreed to a wage deal with Eskom last year after violent protests that intimidated some workers from reporting for duty and exacerbated an electricity shortage that contributed to record outages.

Eskom employees aren’t allowed to strike legally, because the provision of power is considered an essential service.

Read: Stage 9 load shedding warning for South Africa