I could go easily into a very long explanation. Trying to put it simply......
The Exactpower adjusts the voltage and power coming out of it going to your gear. Unfortunitely the quality of the voltage and power going into the Exactpower from the wall is taxing the ability of the of the SP15 to adjust the power.
Dedicated lines may solve the problem if you want to go that far. Or just don't plug the EP15 and SP15 into the same duplex.
The Exactpower adjusts the voltage and power coming out of it going to your gear. Unfortunitely the quality of the voltage and power going into the Exactpower from the wall is taxing the ability of the of the SP15 to adjust the power.
Dedicated lines may solve the problem if you want to go that far. Or just don't plug the EP15 and SP15 into the same duplex.