Section 39.175. Spacings and barriers against short circuit

(a) Switchboards shall have the number of bare parts at different potentials on any panel reduced to a minimum, and these parts shall be effectively separated. If voltage exceeds 750, such parts should be protected or separated by suitable barriers. The parts, including bus bars, should be so located, or provided with such insulating coverings or barriers, that parts at different potentials are not readily short circuited by tools or other conducting objects.

(b) Fuses should be located so as to minimize the danger, in removing or replacing them, of short circuiting parts at different potentials by the fuses or by the hands of the operator.