Disconnection Time Requirements?

[mbrooke]

Why do circuits 32 amps and under require a 0.8 or 0.4 second disconnection time, but circuits over 32 amps are legally allowed 5 seconds? 60-115 volts for 5 seconds is enough to cause injury to the human body. What would possibly be the reasoning behind this?

https://imgur.com/a/iN5TTvr

https://imgur.com/a/04PsLYW

 

[mbrooke]

Actually on a 277/480 volt supply it would be 138 volts from the metal object to the ground a person is standing on.