These BCER employees were part of the Arc Lamp Department and their job was to “trim” – i.e., replace – the two carbon rods that were the principal components of carbon arc street lights of Vancouver in the late 1800s and early 1900s.
The big advantages of the carbon arc lamp over the earlier technologies of gas or oil street lighting methods were that it was much less expensive and the light produced was much brighter. A significant disadvantage of the early arc lamps was that the carbon rods (between which the electric arc or spark created the light) needed to be trimmed quite often. According to one online source, carbon rods in the 1890s needed replacing after a mere 75 hours. By 1911, the technology had improved and rods needed to be trimmed after 175 hours. Even with the 175-hour rod turnover rate, however, a streetlamp needed to have attention by lamp trimmers every 21 days or so.
Within a couple of years of this photo being taken, carbon arc technology for street lamps would be eclipsed by incandescent lights. These only needed replacing 4 or 5 times a year.