Most LED tubes, although they have the same size, lamp base as a linear fluorescent, and possibly a similar lumen output, do not have the same omni directional light distribution. Many luminaires emit 20%-30% less light output with narrower beam spreads when fitted with LEDs. This is especially true of troffers with reflectors that offer batwing (wide-spread) light distribution with fluorescents. This needs to be taken into account when considering the overall 30-50% less power usage by LEDs with increased system efficiencies.
It is likely that the luminaire will need some rewiring and this should be done in conformance with the local electrical installation standards.