If you touched one of the phase conductors on a 480/277V 3-phase ungrounded system what would be the current traveling through your body assuming we used 500ohms as the standard resistance for a human body. I konw on an ungrounded system there will be no current during a L-G fault so what happens when you come in contact with a conductor on an ungrounded system? Will there still be enough current through the system capacitive coupling to cause sever injury?
Now on a solidly grounded system again using the same 500ohm body resistance if you touced one of the phase conductors would this current through your body be 277V/500ohm = .554A, assuming an infinite bus on the 480V system? This does not seem like much current, but I suppose it is enough to cause severe damage to a human.
Now if someone were to come in contact with one phase of this system at an MCC level would the shock current be the same there as it would be lets say if they came in contact with a phase at a downstream lighting circuit that when through an isolation lighting transforer? Would you still use 277V/500ohms in both cases? Would you assume an infinite bus in both cases since the body resistance would be much greater than system impedance? Or would the current be less from the lighting circuit due to the fact that the upstream impedance would be greater at the lighting circuit as opposed to the MCC?
Now on a solidly grounded system again using the same 500ohm body resistance if you touced one of the phase conductors would this current through your body be 277V/500ohm = .554A, assuming an infinite bus on the 480V system? This does not seem like much current, but I suppose it is enough to cause severe damage to a human.
Now if someone were to come in contact with one phase of this system at an MCC level would the shock current be the same there as it would be lets say if they came in contact with a phase at a downstream lighting circuit that when through an isolation lighting transforer? Would you still use 277V/500ohms in both cases? Would you assume an infinite bus in both cases since the body resistance would be much greater than system impedance? Or would the current be less from the lighting circuit due to the fact that the upstream impedance would be greater at the lighting circuit as opposed to the MCC?