brother
Senior Member
Current Effect
1 mA Barely perceptible
1-3 mA Perception threshold (most cases)
3-9 mA Painful sensations
9-25 mA Muscular contractions (can?t let go)
25-60 mA Respiratory paralysis (may be fatal)
60 mA or more Ventricular fibrillation (probably fatal)
4 A or more Heart paralysis (fatal)
5 A or more Tissue burning (fatal if vital organ)
Physiological Effects of AC Current on the Body
Comparison of AC to DC Shock Effects
OSHA 29 CFR 1910.333, as well as NFPA 70E, Chapter 1 requires employees, who are
exposed to the electrical shock hazard, to be qualified and that the circuits or equipment
be deenergized and properly locked and tagged. However, if they must work the circuits
or equipment energized then they must use safe work practices and procedures, and the
appropriate personal protective equipment and insulated hand tools.
Electrical arc-flash
There are two different issues with this hazard, the arc temperature and the incident
energy. The main concern with the arc temperature is the flash flame and ignition of
clothing. At approximately 2030F (960C) for one-tenth of a second (6 cycles), the skin is
rendered incurable or in other words a third-degree burn. With only 1.2 cal/cm2 of incident
A.C. (60Hz) D.C. Effects
(ma) (ma)
0.5 ? 1.5 0 ? 4 Perception
1 ? 3 4 ? 15 Surprise (Reaction)
3 ? 22 15 ? 88 Reflex Action (Let Go)
21 ? 40 80 ? 160 Muscular Inhibition
40 ? 100 160 ? 300 Respiratory Block
> 100 > 300 Usually Fatal
1 mA Barely perceptible
1-3 mA Perception threshold (most cases)
3-9 mA Painful sensations
9-25 mA Muscular contractions (can?t let go)
25-60 mA Respiratory paralysis (may be fatal)
60 mA or more Ventricular fibrillation (probably fatal)
4 A or more Heart paralysis (fatal)
5 A or more Tissue burning (fatal if vital organ)
Physiological Effects of AC Current on the Body
Comparison of AC to DC Shock Effects
OSHA 29 CFR 1910.333, as well as NFPA 70E, Chapter 1 requires employees, who are
exposed to the electrical shock hazard, to be qualified and that the circuits or equipment
be deenergized and properly locked and tagged. However, if they must work the circuits
or equipment energized then they must use safe work practices and procedures, and the
appropriate personal protective equipment and insulated hand tools.
Electrical arc-flash
There are two different issues with this hazard, the arc temperature and the incident
energy. The main concern with the arc temperature is the flash flame and ignition of
clothing. At approximately 2030F (960C) for one-tenth of a second (6 cycles), the skin is
rendered incurable or in other words a third-degree burn. With only 1.2 cal/cm2 of incident
A.C. (60Hz) D.C. Effects
(ma) (ma)
0.5 ? 1.5 0 ? 4 Perception
1 ? 3 4 ? 15 Surprise (Reaction)
3 ? 22 15 ? 88 Reflex Action (Let Go)
21 ? 40 80 ? 160 Muscular Inhibition
40 ? 100 160 ? 300 Respiratory Block
> 100 > 300 Usually Fatal
