Bomb squad end operation at NSW substation

A bomb squad called out to investigate several suspicious objects found at a western Sydney electricity substation have left without finding any explosives.

Maintenance workers found what was mistakenly identified as a petrol bomb with a detonator at the Kingswood substation in South Penrith just before 9am on Thursday.

Emergency crews were swiftly on scene to cordone off the residential area but concluded the operation on Thursday afternoon after no explosives were detected, police said.

The unidentified objects were removed for forensic examination.

Endeavour Energy worked with police over the incident and confirmed that power supplies in the area weren't affected.

The Kingswood Zone Substation supplies around 13,000 homes and businesses including Nepean District and Nepean Private Hospitals.

Nearby Nepean Hospital took advice from police but was not evacuated.

At least one home neighbouring the substation was evacuated, according to social media postings.

Inquiries into the event continue.