Some power still to be restored following Sunday's storm
UPDATE: ESSENTIAL Energy crews are back on the ground this morning continuing repairs to the network following Sunday afternoon's storm.
220 customers in Goonegerry and Federal remained without power overnight, Essential Energy said, with crews restoring supply to 9,600 people throughout yesterday.
Extra teams will be assisting local crews throughout the day and vegetation contractors will also help with the removal of trees over lines and clearing of access ways in to parts of the network that were inaccessible yesterday.
Regional General Manager North Coast, Brendon Neyland, said there was still significant damage that needs repairing in the Federal and Goonengerry areas.
"We will be throwing all our resources in to this area in the hope we can get the majority of customers back on by the end of the day," Mr Neyland said.
"We will also be flying powerlines in the area to ensure we haven't missed any potential vegetation hazards."
Customers may see a low flying helicopter in the Rosebank, Clunes and Dunoon areas as well as Federal and Goonengerry.
INITIAL REPORT: A SUPERCELL storm packing heavy rain, lightning, giant hail and strong winds smashed Lismore Base Hospital on Sunday with a lightning strike the probable cause of scaffolding collapsing and piercing the maternity ward roof.
Bureau of Meteorology meteorologist Katarina Kovacevic said the combination of low-level wind convergence and high-level moisture, coupled with upper-level support drove the storm to become a supercell.
"The storm formed to the south-west of Lismore about 3.30pm and travelled to the north-east and impacted the hospital and the city of Lismore," she said.
"We received reports of 5cm hail, which is giant hail, from the storm at Tatham, before it impacted Lismore.
"An 87kmh gust was recorded at the Lismore airport automatic weather station at about 4pm."
Ms Kovacevic said the storm then took out the instrumentation on the Lismore airport weather station.
"53mm of rain was recorded in 30 minutes at Belongil Creek about 5.30pm as the storm moved north-east and impacted the Byron Bay area," she said.
"By 6.30pm the storm had moved out to sea but was still quite active over the ocean.
"Those things combined to produce a supercell storm."
Richmond Clarence Health Service group executive director Lynne Weir said scaffolding attached to the redevelopment of the hospital collapsed onto the obstetric area of the hospital.
"Nineteen people were inside at the time, five mothers and their babies, two staff and seven visitors," she said.
They were escorted by emergency services to another part of the hospital shortly after the incident.
One nurse was treated for a minor back injury.
Mrs Weir said the hospital remained operational.
"The emergency department was not affected and has continued to operate as normal," she said.
"An exclusion zone had been set up around the site to ensure there is no further risk to patients, staff or the public.
"The construction site will remain closed until a full investigation has been undertaken and engineers have determined the site safe."
The storm blew vegetation into, and brought down, powerlines causing widespread damage, primarily affecting the power supply to customers in Lismore, Ewingsdale, Ballina, Suffolk Park, and surrounding areas, and as far south as Coffs Harbour.
At the height of the storm 9800 customers were without power throughout the Northern Rivers area.
About 1500 Essential Energy customers were still without power yesterday at 3pm.
Some customers in Goonengerry, Federal and Ewingsdale were likely without power again last night.
A Comcare spokesman said Federal work health and safety regulator Comcare was investigating Sunday's incident at Lismore Base Hospital which saw the partial collapse of the maternity ward roof.
"Two inspectors from Comcare's Newcastle office are on their way to Lismore and will be on site early tomorrow morning," the spokesman said.
"Comcare has worked closely with John Holland to maximise work health and safety outcomes at the hospital redevelopment project, and our inspectors visit the site regularly."
A SafeWork NSW spokeswoman said officers at the hospital on Sunday inspected the damage from the natural disaster.
"SafeWork NSW staff inspected the site yesterday to provide advice and ensure the safe clean up of the site," the spokeswoman said.