A spokeswoman for Top Energy, which is replacing power poles along SH10, said the cable was damaged by contractors working for the lines company at a Chorus-supervised site.
Chorus spokesman Nathan Beaumont said up to 5000 customers could have been affected.
The immediate priority was get the service back up and running, after which it would have a "friendly chat" with those responsible about recovering its costs.
A Spark spokeswoman said customers at Te Kao, Kaingaroa, Kaitaia, Houhora, Whangaroa, Hokianga, Maungataniwha, Karikari, Mangonui and Taupo Bay were affected, while a spokesman for Vodafone listed the affected areas as Karikari Peninsula, Cooper's Beach, Houhora, Te Kao and Taupo Bay.
The lower half of the Far North, including the Bay of Islands and Kaikohe, escaped the outage.
Business owners in Kaitaia greeted the outage with a mix of frustration and weary resignation.
Ian Walker, who employs 26 staff across a number of businesses, said the incident could have cut takings by as much as $8000.
His bookshop, an electronics and appliance store and an IT business in particular were affected.
Eftpos didn't work, but staff were able to process some credit card payments by hot-spotting a laptop to a working cellphone.
He found it frustrating that, as with power, a single cable served the Far North. Kaitaia businesses lost about a week a year to various outages, a loss they could ill afford.
"But can you do? Until someone stops talking about the infrastructure we need and starts doing it," he said.
In an era of GPS mapping and cable-sensing equipment it was "bizarre" that it was possible to dig through a cable of such significance, Mr Walker added.
Meanwhile, patient care at Kaitaia Hospital was unaffected, but communication with Whangarei was difficult, Northland District Health Board spokeswoman Paula Martin said.
Kaitaia Hospital's "particularly resilient" staff had business continuity plans in place, and were well versed in dealing with outages. Primary health centres, including Whangaroa Health in Kaeo, were also affected.
Originally it was thought the cable had been cut by contractors carrying out drilling work at Taipa Bridge, as part of the government's one-way bridge replacement programme, but that was quickly established as a possibly malicious rumour.
The outage caused major problems for the Northland Age, but Tuesday's edition got to press in Auckland on time, thanks to a Printing.com cellphone, communication between journalist Peter de Graaf in Kerikeri and the subs in Tauranga, who displayed their ability to hack into Northland Age word processors, and a heroic contribution by the staff at Keri Digital, without whom the rescue mission would not have been possible.
