On the face of it, the proposal seems unfortunate for those most in need of help to afford a home of their own. But if they were exempted, and the lending restriction on others sent house prices lower, those who had borrowed on very low deposits could suffer a worse fate. Their equity would be wiped out; they would owe banks more than their house was worth.
Mr Wheeler was working in the United States when the last housing bubble burst and he saw the consequences for "sub-prime" mortgages. He does not want to send house prices lower, merely slow their rate of increase. He calls the proposal "speed limits".
The limits could take the form of a rule that no more than 10 per cent of a bank's new lending on residential property can be for more than 80 per cent of the property's value, and no more than 5 per cent can be for more than 90 per cent of the value. The discussion paper sets out the likely rules and procedures with such precision that lending institutions will probably start preparing their loan books this week.
The Reserve Bank has clearly learned from the last house price boom when its previous governor, Alan Bollard, spent years trying to talk the market down with warnings of the pain households would suffer when inevitably the bubble burst.
The warnings proved to be overstated, the pain when it finally came was largely confined to investors in finance companies. House prices did not fall as drastically as they did in some countries, sellers preferred to withdraw property from the market and wait.
Mr Wheeler is speaking more softly than Dr Bollard did and wielding a bigger stick. Central bankers everywhere have learned that asset price inflation matters more than they had realised. It can not only fuel consumer prices. It can, and did, destabilise the global banking system. Elsewhere, loan-to-value regulations are being devised for the system's greater security. Here, they are proposed as a means to rein in rampant house prices. Let us hope they can.