Arc-resistant switchgear enclosure with vent arrangement of a lower compartment

An arc-resistant switchgear enclosure, comprising:

• a) exterior walls;
• b) plural compartments within the exterior walls including stacked first and second front compartments, with the first front compartment above the second front compartment, and a rearward compartment, each of the compartments formed by dividing walls that isolate the respective compartment from the other compartments so as to contain an arc fault explosion in the respective compartment from the other compartments;
• c) each of the compartments having a vent in one of the exterior walls to vent an arc fault explosion, the vent of the second front compartment being a second vent and being between the first front compartment and the rearward compartment;
• d) one of the first front compartment or the rearward compartment having an extension across the second vent to the other of the rearward compartment or the first front compartment, the extension isolating an arc fault explosion in the respective one of the first front compartment or the rearward compartment from the second front compartment and also from the other of the rearward compartment or the first front compartment;
• e) electrical conductors extending from the rearward compartment to the first front compartment through the extension.