"I was struck by its beauty and design, but didn't know what it was," Ma recalled. "I was later told it was a 'fire meter', an old colloquial name for electricity meter in Shanghai."

Since that moment, Ma kept a constant lookout for these old meters. As there were hardly any people interested in this object, he managed to build up his collection quickly.

All the meters in his collection were salvaged in Shanghai. And the oldest was made around 1905. The majority of them were made between 1910 and the 1940s.

As his unique collection grew, so did his knowledge of the city. For example, he shared that it was through these meters that he learned about the opening of the first power plant in Shanghai in 1879 and the inaugural lighting up of 16 road lamps on the Bund in 1882, which marked the beginning of power supply in the city.

"Shanghai was the first city in China to use electricity. Soon after the technology was developed in the West, it was introduced to Shanghai," says Ma.

"With the introduction of electricity meters, electrical power could be measured, widely used and merchandized. These objects remind us of the past and the importance of electricity and saving power," he adds.

"These meters belong in a proper museum, but because there is no museum about electricity in Shanghai, I built one myself. It is my mission to keep these objects as evidence of the city's history."