Wire color in Recreational Vehicles
Posted: Wed May 01, 2013 7:52 pm
I'm not sure if this standard has changed or remains the same. I own a 66 Airstream and like Techman2015's video:
http://youtu.be/nAUExEovzlE
...like Techman2015's video, mine also uses a black wire for positive. Just working it out logically, measurements show (in my camper) that there is no dedicated negative wire. They put ground on the white wire. I also have a ground in my romex and normally the ground and white are bonded (connected) together as they are in my camper. So, in the spirit of cheapness, they don't have to run a ground wire for the DC if they do this, there are no issues (that I've detected) with this setup other than making it weird to hook things up. Normally in DC powered devices, ground is always black or green and positive is usually red or whatever the lightest color is. It seems to me that in keeping with the education of the trailer builders, they are using an extra black wire for 12V which is considered "hot" just as there is a hot wire in the 110v AC system. You cannot mix the 12v DC with the hot side of the AC circuit. It is always a separate wire. It's a bit confusing, but I thought I would throw up what seems like the most likely explanation of why they use black for positive in an RV. If I were building an RV, I'd use red and tag the wire every so often. I'd also include a note in the DC breaker box indicating the wire colors. It's an important principle of safety to leave things so another mechanic and follow along.
Happy Connecting!
Dave Thacker
Radicalrc.com
http://youtu.be/nAUExEovzlE
...like Techman2015's video, mine also uses a black wire for positive. Just working it out logically, measurements show (in my camper) that there is no dedicated negative wire. They put ground on the white wire. I also have a ground in my romex and normally the ground and white are bonded (connected) together as they are in my camper. So, in the spirit of cheapness, they don't have to run a ground wire for the DC if they do this, there are no issues (that I've detected) with this setup other than making it weird to hook things up. Normally in DC powered devices, ground is always black or green and positive is usually red or whatever the lightest color is. It seems to me that in keeping with the education of the trailer builders, they are using an extra black wire for 12V which is considered "hot" just as there is a hot wire in the 110v AC system. You cannot mix the 12v DC with the hot side of the AC circuit. It is always a separate wire. It's a bit confusing, but I thought I would throw up what seems like the most likely explanation of why they use black for positive in an RV. If I were building an RV, I'd use red and tag the wire every so often. I'd also include a note in the DC breaker box indicating the wire colors. It's an important principle of safety to leave things so another mechanic and follow along.
Happy Connecting!
Dave Thacker
Radicalrc.com