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48V DC is mostly popular because human safety laws don't require special handling of 48v. Voltages above 48v/50v normally require testing/certification/etc.

48v is basically a voltage to avoid paperwork, while still being as high as possible to avoid spending too much money on copper.

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> 48v is basically a voltage to avoid paperwork

A less cynical take is that it’s a safe voltage for people to work with.

Please grab two terminals of a -48v system and repeat that statement.

I don't have a -48VDC power supply to test it with, but as far as I know +48VDC has the same effect. Firmly grabbing a lead with both hands results in absolutely nothing happening.

>I don't have a -48VDC power supply to test it with, but as far as I know +48VDC has the same effect.

Grab the same leads of +48VDC, but switch your hands, left lead to your right hand, right lead to your left hand. You will get -48VDC.

Doing it with wet sweaty hands is somewhere between "pretty painful" and "deadly". You're right that with dry non-sweaty hands, you can't even notice 48 volts.

If you do it a lot, you get used to it. (I work with 350VDC and 120VAC a lot with sweaty hands)

> and "deadly”

Hit us with those stats on people killed by touching 48volt systems. Compare that with people killed by AC at home.

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