Question $4$

$-$ A sole owner $($without employees$)$ of a contracting firm was performing maintenance and repair work for a cork processing company.

$-$ He was working on the motor for a Nu Vac $480-$volt, $14\mathrm{.}9-$kilowatt pneumatic roofmounted conveyor system. He found the motor to be running roughly. As he was examining it$,$ the motor tripped the electric starter.

$-$ He went to the electrical room on the third floor of the building to open the Square D $60$ampere, standard$-$duty disconnect switch rated at $600$ volts fed from the motor control center for the production line. The main circuit breaker for the motor was not turned off.

$-$ An explosion and electrical fault occurred, involving not only the switch but also a portion of the surrounding electric equipment.

$-$ The ensuing electric arc burned the contractor. He was hospitalized with first$-$ and second$-$degree burns to his right hand and arm and his face.

$-$ The company processed cork, including grinding, sifting, and blending cork. Because of inadequate housekeeping, combustible cork dust was present throughout the electrical room. The open$-$type electric equipment was unsuitable for use in Class II$,$ Division $1$ or $2$ locations.

The arc$-$flash boundary for this case is $5$ ft $.$

The restricted boundary for this case is $1$ ft $.$

The company should have followed requirements in NFPA $70$E Article $235$

The job should have been done under an electrically safe work condition.

The job should have been preceeded by an energized electrical work permit.