Jonah Lomu's star power has helped get more people whose health is at risk during power cuts to register with electricity companies.
In a television commercial, Lomu discusses how he had a dialysis machine in his home and required this to live, and appeals to people in similar
situations to alert their power provider.
The advert, which went to air a couple of weeks ago and is fronted by Lomu, who suffered from nephrotic kidney syndrome, was funded by electricity providers and lines companies in the wake of the death of Folole Muliaga in May.
Mrs Muliaga, 44, died less than three hours after power to her home and her oxygen machine was cut off by a contractor for Mercury Energy because of an overdue power bill of $168.40.
Mercury Energy spokeswoman Chantelle Urquhart said the company had seen a "significant increase" in the numbers of vulnerable customers registered, although she declined to say what that figure was.
Ms Urquhart said the response was likely a combination of the Muliaga incident and the advertisement campaign.
A spokesman for Genesis Energy, Richard Gordon, said the supplier had seen a 20 per cent increase in medically dependent customers registering with it over the past two months.
"Since that time we have had about 200 more people join the already 980 people we had on our database."
Jonathan Hunt of Contact Energy said there had been a "pleasing and significant uptake" of those calling up for medical dependence which he attributed to the advertising campaign.
He said a couple of months ago there were about 70 medically dependent people registered among its 500,000 customers but that now exceeds 500.
TrustPower spokesman, Graeme Purches, said they "had not been inundated with calls" since the advertisement began.
He said the company's processes were robust in dealing with the 700 medically reliant customers on its database but the onus was on new clients to make their situations known to their providers.
A spokesman for the Muliaga family, Brendan Sheehan, said he had seen the advertisement and was "pleased something is being done about the situation".
