The first spell saw the visitors win the attrition and territory battle (84 percent in that 40 minutes), posting two tries for a 14-0 lead.
Wing Johnny McNicholl was again amongst the tries, latching onto a Rob Thompson chip kick, while hooker Ben Funnell burrowed over after yet another effective lineout drive.
Canterbury's kicking game was more telling, while Harbour, desperately in need of field position, tended to kick to hand, not land. They did win their ball through the likes of tireless lock Gerard Tuioti-Mariner, and tackled gamely. No 8 Hapakuki Moala-Liava'a carried with admirable vigour. But their mistake rate was higher than that of Canterbury and the three games in eight days started to take their toll. Canterbury's scrum, anchored by Nepo Laulala, exerted real heat.
Matt Todd, one of the most unheralded players in New Zealand rugby, was again ubiquitous and a nuisance in the breakdown. He never plays a poor game. Second five Rob Thompson, as he was against Hawke's Bay, was penetrative.
There was more bad news for North Harbour. Earlier in the week, it was confirmed that centre Rene Ranger would not be available for the rest of the season after he was not given the all-clear by the specialist to return to rugby.
North Harbour next travels to Manawatu on Saturday, while Canterbury have just three days to prepare for Waikato on Wednesday night.
In the curtainraiser, North Harbour Under 19s upset their Auckland counterparts 15-9, putting them in good seeding position for the Jock Hobbs Memorial Under 19 tournament in Taupo, which starts on Sunday.
Canterbury 17 (Johnny McNicholl, Ben Funnell tries; Tom Taylor 2 con, pen)
North Harbour 10 (Tevita Li try; Matt McGahan con, pen)
Halftime: 14-0