The incident occurred around 4pm between Japan and Kelp streets.

The powerline appeared to be connected to a single residence but it is unknown how many properties are affected.

Meanwhile Portland District Health has enacted its emergency contingency plans after the hospital was hit by lightning on Tuesday night.

The lightning strike about 8pm hit the Vodophone tower on the hospital roof and arced through a water pipe.

The strike damaged some of the hospital's internal communication systems which are currently being repaired.

It is expected that all systems will be restored and back in use by 8am Thursday.

PDH was operating in emergency mode on Wednesday, but there has been no threatto patient safety during the incident.

Acting Chief Executive Officer Ros Jones said experts had been called in to repair the damaged fire panel and internal communication systems.

"In the meantime we have enacted our contingency plans to manage the situation and ensure services continue as normal," she said.