Top load or "toroid" electrode\n\n Most Tesla coil designs have a smooth spherical- or toroidal-shaped metal electrode on the high-voltage terminal. The electrode serves as one plate of a capacitor, with the Earth as the other plate, forming the tuned circuit with the secondary winding.

The topload of a Tesla coil is placed directly above the primary coil to help control the electrical discharge and improve the efficiency of the coil. Placing the topload at the side may not provide the same level of control over the electrical discharge and could impact the performance of the coil.