Why stop at 44?

The cover of this cabinet enclosing a panelboard was in operation with no apparent signs of any failure. I was interested in the numbering scheme, and asked myself, “Why were the numbers 43 and 44 engraved on the cover?” I was unable to remove the cover because I was on private property, and didn't want to press my luck. If a panelboard is used as a lighting and appliance branch circuit panelboard, the spaces are limited. See Section 384-15 where the number of overcurrent devices on one panelboard in any one cabinet or cutout box cannot be more than 42 overcurrent devices (other than those provided for in the mains). A lighting and appliance branch circuit panelboard must also be provided with physical means to prevent the installation of more overcurrent devices than that number for which the panelboard was designed, rated and approved. For the purposes of Article 384, a two-pole circuit breaker is considered as two overcurrent devices and a three-pole circuit breaker is considered as three overcurrent devices.