A single loudspeaker in a line array can draw up to 24A at 240V [0]. Even a very small rig of 6 speakers would require over 30kw. A 50kw UPS [1] can be purchases for a very affordable $25,000 in 2016 [2]. When building a performance art venue in 1960 or today, a technical ground is a much more suitable option than a UPS.