# Separate DC wiring for lighting.

**URL:** <https://boards.straightdope.com/t/separate-dc-wiring-for-lighting/641030>\
**Category:** Factual Questions\
**Created:** [November 14, 2012, 9:34pm UTC](https://boards.straightdope.com/t/separate-dc-wiring-for-lighting/641030 "2012-11-14T21:34:38Z")\
**Posts on this page:** 1\
**Page:** 2

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**Author:** ![Michael63129](https://avatars.discourse-cdn.com/v4/letter/m/3da27b/32.png) [@Michael63129](https://boards.straightdope.com/u/Michael63129)\
**Post date:** [November 16, 2012, 8:55pm UTC](https://boards.straightdope.com/t/separate-dc-wiring-for-lighting/641030/21 "2012-11-16T20:55:48Z")

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> [@beowulff](#):
>
> Man, did you take an extra does of your pedant pills today?  
> What exactly, does a rectifier _do_, if it doesn’t convert AC to DC?

Maybe I should have been more clear (I know perfectly well how a SMPS works since after all I have designed quite a few myself, including with more sophisticated stuff like PFC); I was replying to a post that suggested that there was a significant difference in a AC/DC SMPS and a DC/DC SMPS when they are really the same thing except for a rectifier (which may be present in DC anyway since it eliminates polarity issues, but having hard-wired power installed by electricians would avoid problems, eliminating the ~1% efficiency loss; of course, the centralized power supply would still take in AC and you would have losses there).

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