Testing of the prototype Booster dipole magnet at full current produced measurable disturbances of the beam position at the National Synchrotron Light Source. Power for the magnet and the NSLS are distributed from three substation transformers at Temple Place. Normally the substation configuration is for two independent 13.8 KV buses, derived from the 69 KV LILCO distribution. The buses are connected through a circuit breaker that is normally open circuited. Power for the magnet test is derived from one of the 13.8 KV buses and power for the NSLS is derived from the second bus. Coupling of the pulsating magnet load and the NSLS is at the 69 KV level. However, on the days that the interference was first observed at the NSLS only one-half of the substation transformers at Temple Place were in service. The 13.8 KV tie breaker was closed and the full substation load was supplied from this common bus. Thus the coupling between the pulsating magnet load and the NSLS was at the 13.8 KV level. Establishing the normal two bus configurations at Temple Place appeared to reduce the disturbance. These events suggested a controlled experiment to measure the magnet power swing and the induced powerlinemore » flicker; and from these measurements project the flicker on the lab site generated by the Booster operating at full energy. This experiment could corroborate the validity of the electrical models used in analyzing the power flow from the LILCO power grid and its distribution on the Lab site described in Accelerator Division Technical Note 220.« less