A useful thing to Tesla coil builders is a power factor correction capacitor.  When you have an inductive load on an AC circuit, the phase is shifted 90 degrees, the primary of our step up transformer is an inductor, so it is shifting the phase of the current.  This means for a given voltage it is difficult to supply the amount of current needed to drive the transformer, but it is possible, all the transformer needs to do is draw excess current from your breaker box.  It does this.  So by turns ratio the amount of current you are drawing is lower than the amount you actually draw.  If only there was a way to remove this shift in phase, oh wait, there is, a capacitor.  A PFC cap is put in parallel with the primary winding and shifts the phase back to where it belongs.  Generally one uses a properly duty cycle and voltage rated capacitor for 60 Hz 120 or 240V AC.  A good example of such is motor run capacitors (not motor start which have a short duty cycle).  Here is a picture of my PFC caps and MOT ballast.