It's an affectionate term - PON by its true definition is a helluva lot larger, but it's easier for us to quickly chat about PON's as opposed to Splitter Nodes ... especially when you are mentioning them hundreds of times a day
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For info - a PON (Splitter Node) is provisioned for 120 premises (not 32), maximum. Yes, there are grey area's where we can up this, but as a rule, it is 120 THP (Total Homes Passed).
I think you are referring to the SASA (Splitter Array Sub Assembly), which splits the one fibre light into 32 separate lights. A PON will have a maximum of 4 x SASA's in the large joint in which it is housed. Out of the 32 potential light sources, only 30 will be used - ergo 4 x 30 = 120THP.