Main lugs loadcentres typically are used as an add-on load center and is connected to the service entrance loadcentre when spaces for more circuits are needed or when a main disconnect is located elsewhere. It does not contain a main breaker. 4 Spaces, expandable to 8 circuits maximum with the use of QO Tandem breakers. Type 1 Indoor Enclosure with surface mounted trim. CSA approved for vertical, horizontal or inverted mounting. Accepts aluminum or copper conductors. Main Wire Size - AWG/kcmil Al/Cu: #8-1.