Compact fluorescent lamp ballast has high voltage and current and no isolation for the technician between the AC power outlet and fluorescent lamp ballast. Isolation transformer will help between the AC main and compact fluorescent lamp ballast. The voltages are often 10,000 V and the current is high to ionized the argon and mercury vapor gases, homogenous mixture noble gas and toxic mercury gas to an excited state and falls back to emit a photon of ultraviolet light to struck a phosphorus coating to convert the ultraviolet to visible light. Ceramic resistor as mention by others would make a good load to measure the current. Yes, a high voltage proble like those used to measure a fly back transformers in the past, when cathode ray tubes were used as television and computer display screens are a must or a clamp on amp probe Using Ohms law to figure out the voltage, by knowing the current on both sides of the high current ceramic resistor, really large size resistor. This is my thoughts, but seek someone with more experience, if you have questions. Electronic fluorescent ballast have little isolation from the AC power outlet to protect the individual doing the measurements.
Lawsen