I wouldn`t necessarilly worry about it, we all pronounce things differently anyway. I expect there`s a whole load of things you say differently to me, given our respective locations (though actually I don`t sound very Welsh at all these days). And one individual to another will do things differently too, depending on generations, original place of origin or who else they spend most time talking/listening to.
That said, if I don`t say "high pressure sodium", I have always pronounced "SON" rather than spelling it out letter by letter, but I say it as "song" without the G rather than as in "sun"/male offspring. Your local pronounciation preference may differ! As for the thing illuminating this room right now (yes, really, just put in a new tube infact), well I`ll admit I usually call those "low pressure sodium" but if pushed, it would be "socks" moreso than S-O-X. Generally though, I don`t favour abbreviations and anacronyms as there are too many in use today and often confuse the pants off me!
