What is the QMB branch switch replacement criteria?

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Issue:
QMB branch switch information

Product Line:
QMB fused switches

Environment:
QMB Branch switches

Cause:
Selection criteria

Resolution:

Type QW (38-inch Wide) Manufactured Before 1984

Type QW panelboards were built to accept bolt-on 400 A and 600 A Series 1-4 switches. 30-200 A Series D2 switches may be installed using the plug-on extension assembly.

Type QM (31-inch Wide) Manufactured Before 1961

Panelboards manufactured before 1961 have the interior mounting rails facing inward (toward the bus). Switches and circuit breakers that fit in this interior type are obsolete.

Type QM (31-inch Wide) Manufactured After 1961 But Before October 1984

Panelboards manufactured after 1961 have the interior mounting rails facing outward (away from the bus). This interior accepts Series 1-4 switches and Series D2 switches (shown above with required rail extensions). Order the Series D2 switch (includes mounting rail extensions).

Type QMB Manufactured After October 1984