"Vector says the public should be aware of the potential electricity related hazards strong winds and heavy rains can create."
In particular, people should:
• stay well clear of fallen power lines or damaged electrical equipment and treat them as live at all times
• watch out for falling tree branches as these can cause damage to power lines
• avoid possible damage to electrical appliances (in the unlikely event there is a power surge when the power is restored) by switching off appliances at the wall
• keep a torch and spare batteries handy and ensure that you have at least one telephone that does not rely on electricity for operation
• ensure an alternate fuel is always available for cooking (eg gas for barbecue).
Anyone using medical equipment that relies on electricity should ensure they are prepared for power disruptions and if there is an immediate health threat, contact their health provider or call 111, the spokeswoman said.
Extra staff have been rostered on to deal with any potential outages caused by the rough weather, she said.
"Vector will work hard to restore power as quickly as possible, however in storms the company has to prioritise multiple demands. The safety of the public and Vector's contracting field staff is of primary importance at all times."
Computer models were placing the centre of the storm to the east of New Zealand on Monday, WeatherWatch head analyst Philip Duncan said.
"This is a huge storm and will be far too close for comfort - meaning eastern areas like East Cape, Gisborne, eastern Bay of Plenty and northern Hawkes Bay may well be exposed to damaging winds on Monday," he said.
"No one should be underestimating the power of this storm - if the weather isn't severe on Monday it will not be because the storm wasn't there, it will be that it narrowly missed us - the weather version of dodging a bullet, if that eventuates."
The eastern coastline of the North Island was at the highest risk for potential severe weather, from Northland to Wairarapa, he said, but particularly East Cape and Gisborne areas.
"Incredibly rough and dangerous seas will pound the east coast, developing later on Sunday and lasting, for some eastern areas, most of next week," Mr Duncan said.
"This cyclone has so much power and energy in it that the sheer size of it rotating means that it will occasionally 'wobble' left and right - which is why precisely predicting the path of the damaging portion of the storm is so tricky. But certainly the north eastern side of the North Island is exposed to severe weather from Pam, mostly on Monday."
The Chatham Islands will also be especially exposed to the storm - which may directly track over it, Mr Duncan said.
Civil Defence also advised people to keep up to date with the latest news from local councils.
Gisborne District Council has told people to get ready for high winds, large sea swells, rain, coastal erosion, road closures and power loss from late Sunday.
The council's emergency management chief Richard Steele said people living or holidaying in coastal areas should take extra care because large swells could cause seawater to reach further inland than normal.
"Freedom campers should pack up their tents and move away from the coast," Mr Steele said.
"Everyone should be clearing gutters and tying down anything likely to be blown about - such as boats, trampolines, outdoor furniture and rubbish bins," he added.
"We advise people to be prepared. Make sure they have enough food and water to last for three days, and that they have any medication they need. The key message is to be prepared and be self-reliant."
