12V

talking about the lighting etc..?

no.. thats backwards

black is is PLUS aka hot

white is neg aka ground

same thing at the trailer battery connections

thanks, glad I asked. I'm wiring in a 12V receptacle (lighter type socket).

You really should be testing this with a volt meter. My trailer had a number of connections backwards. The QC on these RVs is not very good.

Three things - meter, meter and meter.

In my trailer they have white and purple in some areas. Not pink or reddish, but dark shade of purple.

Use a volt meter to be sure of the polarity. In my trailer Red is hot and Black is ground from the battery to half to the electrical, the other half is White and Black.

vote #3 for using a meter

Why a meter if the wire is color coded?

Black to the fuse panel fuse, white to ground. Color will not change at the connector.

Personally if pulling wire I use Red/Yellow from boating.
https://www.defender.com/pdf/abyc-wire-color-chart.pdf

Where automotive OEM uses B&W, white is always neg
Where automotife OEM uses Red & blk, black is always neg

Test with a meter because wire colors CAN change at connectors. Never trust the codes. Someone may have screwed up.

With RV 12vdc wiring, white is normally negative/ground and every other color is positive/hot. But you should always verify.