Wire size for B&C regulator. Curious, not important.

[Freemasm]

Same current and probably not enough run length difference of the individual leads to matter, most installs. Any guesses why different gage for field current to/from the reg? Something I'm not seeing?

 

[JDA_BTR]

The alternator needs less current than the alternator + regulator combination. So the wire from the ALT FLD breaker is bigger to support both loads, and then the 20AWG to the alternator is all it needs to be for the rated current.

 

[Freemasm]

but both are protected by the same 5 amp breaker. Is there (significant) internal resistance in the regulator proper? Thx

 

[PaulvS]

but both are protected by the same 5 amp breaker. Is there (significant) internal resistance in the regulator proper? Thx

You could use 18 AWG instead of 20 AWG to the alternator if you wanted to, I think that's what I did for a bit more mechanical strength through the FWF area.