An EPS grid or plasma grid was a component of the electro-plasma distribution network on Starfleet vessels from the 22nd century onwards. In the event of an emergency, the grid may be shut down to avoid an overload. By the 24th century maintenance was performed on the grid at regular intervals.
In 2151, Lieutenant Malcolm Reed bypassed the EPS grid to receive power from Enterprise's impulse drive to get the phase cannon online, Trip Tucker denied this possibility, but later allowed it. (ENT: "Silent Enemy")
When the Enterprise crew were locked in their quarters by Suliban forces in 2152, Tucker rerouted the comm signal through the EPS grid, enabling him to talk to anyone on B Deck. (ENT: "Shockwave, Part II")
In August of 2152, while under the influence of radiation emanating from a nearby singularity, Malcolm Reed requested Tucker's assistance in preparing an emergency shutdown procedure for the EPS grid. (ENT: "Singularity")
In 2370, Donald Kaplan jibed Geordi La Forge that by cleaning the USS Enterprise-D's plasma grid they might match the power conversion level aboard Kaplan's vessel, the USS Intrepid. (TNG: "Force of Nature")