Forestry machine in question is the Thermionic Fabricator.

I tried placing a universal energy cable on every side of the Fabricator, however, it wouldn't receive power

EDIT:
Forestry version: forestry_1.7.10-4.2.3.51
Mekanism Version: Mekanism-1.7.10-8.1.7.252

Adding CoFH Core to the instance fixed the issue