Officers shut down Lesueur Rise for more than seven hours as bomb technicians used a robot to take samples from a package of suspicious chemicals found about 10am.
The samples were discovered to be non-explosive, but police thought they might be connected to the manufacture of illicit drugs.
Yesterday, police said there would be no further investigation into the matter.
“The chemicals turned out not to be illegal and the investigation is completed,” a police spokeswoman said.
Western Power disconnected the transformer as a precaution, leaving about 140 nearby homes without power from 11am to 6pm.
“As soon as police advised Western Power their investigations had concluded and our crews determined it was safe to do so, we re-energised the transformer and restored power to customers,” a utility spokesman said.