The S2415H ships with =

So all you would need is a standard extension cable to plug into the power cable if the unit was too far from a wall outlet.

wall outlet --> extension cable --> 6ft power cable --> 6ft power adaptor ---> S2415H power in

I actually need an extension from the monitor end, the way my desk is setup the box portion of the adapter is on the desk and there is not enough cable from the monitor to the box so that the box can be hidden under my desk.

Dell has never sold any such extension.

I have never heard of one.

Is there another adapter I could use that has a longer cable from the box to the monitor?