Have recently been chasing up same sort of info regarding Reversing lights.
Unfortunately watts to brightness is not possible as they are different scales of measurement. ( And the ADR regs quote lumens (?) not watts.... yet to see a bulb advertising other than watts )
However as a rule of thumb I got this info from a Bulb catalogue:
Quote:
Watts vs. Candle Power As a guide, the following comparisons can be
made between these 2 measurements of power or brightness:
2w = 3cp
6w = 6cp
10w = 15cp
16w = 21cp
25w = 32cp
35w = 50cp
If you have a look at the Narva web sie they have a list of ADR compliant lights - and you could look up specs of appropriate fitting...
http://www.narva.com.au/ADR_Listing_1.html