The CSG303012 is a 30 x 30 x 12 in (762 mm x 762 mm x 305 mm) Type 1 unpainted galvanized steel junction box with a flat screw cover and no knockouts. It is designed for general purpose indoor commercial use as a junction, pull or switch box, making it a fit for electricians, electrical contractors and facilities teams who need a plain, unpunched steel box at this size.

The body is formed and spot welded from G90 steel, and both the enclosure and cover are left as unpainted galvanized steel. The flat steel cover is fastened with plated steel screws, and keyhole slots let the cover be lifted off without removing the screws entirely. Because the box has no knockouts, conduit entries can be located exactly where the installation requires them, and a grounding location is embossed in the body.

Enclosure dimensions are 30 in high, 30 in wide and 12 in deep (762 mm x 762 mm x 305 mm), with the drawing showing 12.10 in overall depth. Shipping weight is 98 lbs (44.45 kg), and the part ships packaged in a box. The 30 x 30 in face is offered in 6, 8 and 12 in depths; CSG303012 is the deepest of the three.

Through holes in the back allow wall mounting. The box is rated UL-50 Type 1 (UL File E65324) and CSA Type 1 (CSA Cert. LR21001), complies with NEMA Type 1 and IEC 60529 IP20, and is listed as REACH and RoHS compliant.