Commentary for Exodus 39:37

THE LAMPS THEREOF, EVEN THE LAMPS TO BE SET IN ORDER. It is possible that there are candelabrums with lamps on them purely for decorative purposes, or that they should give additional light if more is required. But this was not the case with the candelabrum of the Sanctuary, for it only had seven lamps. Therefore He explained, even the lamps to be set in order, for they were always set in order at dusk.

את נרותיה נרות המערכה, ”its lamps the ones of the prescribed order,” Nachmanides writes that it is possible that generally speaking, candelabra were equipped with lamps whose light-giving mechanism was adjustable so that depending on the need for more or less light, the wicks and their supply of oil would be regulated. To reflect this mechanism, the Torah may have added the expression נרות המערכה. The singular mode used in this expression is to inform us that the Menorah in the Tabernacle did not have such a mechanism, but that the oil supply to the wicks was maintained at a constant rate. [Except for the light on the center shaft, the other lamps were lit in the evening, and the oil supply allowed for the length of the night. Ed.]