What is the difference between QMB and QMJ fusible branch units?

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Issue:
Product Design Features

Product Line:
QMB QMJ panelboards and switchboards

Resolution:
The QMJ switches are suitable for use with Class J fuses only.

The QMB switches as standard accept a Class H or K fuses for use on systems up to 10 kAIC and Class R fuses with a Class R fuse kit for use on systems up to 200 kAIC. Then many of the QMB switches can be modified to accommodate Class J fuses by moving the load base assembly to a location marked on the enclosure. Also, some of the QMJ switches will be in a smaller footprint enclosure.