The prosecution was bought by Kensington and Chelsea Council after officials visited sites in the area.
Council officers visited Adam and Eve Mews and Queen’s Gate Mews last year in May to inspect works being carried out by UK Power Networks.
During the inspections officers found operatives working on site with an open excavation and a mini digger and works on a large excavation with an open trench were happening partly outside of a residential property.
On both occasions UK Power Networks Operatives had failed to fully enclose the works area with a continuous barrier system to keep members of the public safe from harm.
The company pleaded guilty at an earlier hearing to charges under the New Roads and Street Works Act and was sentenced at Westminster Magistrates Court this week.
Cllr Cem Kemahli, Lead Member for planning and public realm said: “The outcome of this case is a good result, but it’s disappointing that we’re still having to bring these cases to court at all. It is the bare minimum to ask that companies make sure our streets are safe when they are working in them.
“We will continue to hold those companies to account who neglect safety measures, so we can drive up standards and protect the public.”
UK Power Networks said: “Our highly trained teams always strive to maintain a safe environment around our streetworks and we apologise that on these occasions our high standards were not met.
“To maintain reliable electricity supplies for local homes and businesses, connect and modify power supplies, we carry out approximately 13,700 excavations annually in London. As part of our constant focus on compliance, we have completed further refresher training and briefings with our teams.”