Say, we have two particles of equal and opposite charge in an isolated system in which we neglect gravity. The energy of particle 1 is: E1 = U1 + T1 Where U1 is electrostatic potential energy and T1 is the kinetic energy of particle 1. The energy of particle 2 is: E2 = U2 + T2 Where U2 is electrostatic potential energy and T2 is the kinetic energy of particle 2. Therefore, the total energy of the system should be: E = E1 + E2 = U1 + U2 + T1 + T2 Where U = -kq^2/r If we let the kinetic energy of both particles be zero then: E = U1 + U2 = -kq^2/r -kq^2/r = -2kq^2/r The electrostatic potential energy of this system of two point charges is the energy (E = -2kq^2/r) when we neglect T (set T=0). However, according to my book "Introduction to Electrodynamics" by David Griffiths, and Wikipedia "https://en.wikipedia.org/wiki/Electric_potential_energy", this is incorrect. Both of these sources would claim that the electrostatic potential energy of this system is -kq^2/r not 2kq^2/r. I am incredibly confused as to why they believe this or how my analysis could possibly be incorrect. It's not too hard to believe that Wikipedia is wrong, but my book for the two courses I took in electrodynamics is wrong too? That is hard to believe, and so I'm looking for another's perspective.