Well that's right, that + on the ground in the control panels (or -48V power supply if you prefer) has always increased my attention. Interestingly, this power supply scheme has survived and radios for licensed bands still have the + power supply connected to the chassis.
DC power supplies, but also smaller power supplies with batteries and even UPS and VRLA battery strings also increased my vigilance, the effects of a short circuit could be quite explosive and dangerous due to the temperature and splattering of evaporating metal. At higher voltages on the battery string you have to be careful with shock as DC can lead to electrolysis of the blood, the effects of which can show up in the days to come....
DC power supplies, but also smaller power supplies with batteries and even UPS and VRLA battery strings also increased my vigilance, the effects of a short circuit could be quite explosive and dangerous due to the temperature and splattering of evaporating metal. At higher voltages on the battery string you have to be careful with shock as DC can lead to electrolysis of the blood, the effects of which can show up in the days to come....
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