The recent push to higher testing voltages for research and production tests onUHV system components rated above 800kV class has led to difficulties in achieving thestandard waveshapes as required by IEC60060 Parts 1 and 2 and other existing IEC,IEEE/ANSI and other standards. One of the limiting components in achieving themaximum capacitive loading on an impulse generator for standard lightning impulse fronttimes is the inductance of the circuit. The total inductance of the circuit is comprised ofthe internal inductance of the impulse generator and the inductance of the loop toconnect to the load. The higher the voltage class of test objects, the larger the loop,yielding more inductance that in turn, reduces the test capacitance that can be connectedand still remain inside the overshoot requirements of the standards. The internalinductance of the impulse generator is comprised of the wiring of the stages and thestage capacitor inductance and/or the inductance of the waveshaping resistors. Thispaper shows the results of methods to measure and calculate the internal inductance ofseveral impulse generators and we review the formulas for calculating the maximum loadof an impulse generator with a given internal inductance. We believe these methods givemore realistic values than adding up nameplate inductance values from an impulsegenerator. The paper also reviews the pros and cons of higher stage capacitances inimpulse generators to test larger loads that are ultimately limited by the circuit inductancevalue. The intent of this paper is to assist in the revision of future IEC and IEEE standardsfor impulse testing apparatus in the UHV range