After a break of two years, Forrest couple David and Janean Richards have again festooned their house with Christmas lights to raise money for SIDS (sudden infant death syndrome) and Kids ACT.

This time there will be 500,000 lights on 48 kilometres of string - about enough to run from one end of the ACT to the other.

But they will not be turned on until December 1, so the national capital will have to wait a little longer for the spectacle it creates, with up to 70,000 people visiting the lights in 2011.

The Richards won the Guinness world record for the most lights on a residential property on December 4, 2011 with 331,038 twinkling lights. They then had a year off and the record was broken - on November 23, 2012 - by a family in Lagrangeville, New York, who set up 346,283 lights.

Mr Richards admitted reclaiming the record was part of his motivation for setting up the lights again this year - despite having to start stringing them up last month.

''It was sort of a reason to do it again, and they didn't break it by very much,'' he said. ''I thought 500,000 was a nice, round number so I decided to go all out because I may never do it again.''

Another motivation was providing a one-of-a-kind wedding venue for Mrs Richards' cousin Luana Marriott, who married Patrick Cormac at the Forrest house on Saturday night with only the white lights turned on, creating a spectacular effect.

''It was amazing,'' the new Mrs Cormac said. ''David said he would put up the lights and make it stunning. It was amazing how they opened their home to us. They are so giving.''

Mrs Cormac, a director at the federal government's overseas aid program, said, ''It was unforgettable.''

Mr Richards' goal this year is to raise $100,000 for SIDS and Kids ACT. The effort in 2011 raised $77,000, simply through gold coin donations, meaning two part-time counsellors could be employed by SIDS and Kids to help with bereavement and education around SIDS, miscarriage and stillbirth.

''It actually helps a lot of families who have put up with an amazing amount of grief. That makes it all worthwhile to me,'' Mr Richards said.

Guinness World Records Australia representative Chris Sheedy will visit the house on Sunday to look at delivery dockets and tradesmen's records, all legally verified, to ensure all the lights have been delivered and erected. ''I fortunately don't have to count 500,000 lights,'' Mr Sheedy said, with a laugh.

The record will also have to be endorsed by Guinness in England.

Mr Richards buys all the lights himself and all donations go direct to SIDS and Kids. He estimates his electricity bill will go up $2500 for the month. ActewAGL is sponsoring the lights through its Green Energy program.

Mr Richards said he was also looking to enlist more corporate sponsors to help fund-raising efforts. And he is up for the effort of his month-long display.

''It's like a party in your driveway every night.''