Originally Posted by rwidman
My boat is old enough that black signifies negative. So, if I see a black cable I know that's what it is. Common practice if you're using a wire of cable for some other purpose than it's color would indicate is to mark both ends with the appropriate colored electrical
tape or heat shrink tubing.
If memory serves me my boat's original battery
cables are all black with the positive ends marked red as above. Stuff I've added I use the appropriate colored cable or wire.
If someone really wants to label cables, nice writable heat shrink labels are available from on-line vendors.
Ron - just to make sure you know what I was referring to - it was not on how to mark negative cables with a permanent black marker. That would not be recommended. I was only speaking to how I mark the orientation of the cable to the lug when I am assembling them for installation
As to your comments, the heat shrink labels can work (depending) as well as other types. Almost every type of labeling I have seen does tend to fade after a few years though. When I am running new cable I always run black for negative and red for positive, unless I am working on a European boat which uses yellow for negative.
If the appropriate color is not available then you have to mark the hell out of it to make sure it is obvious what it is for. Of course, if it is connected to the battery negative you can assume that is what it is for, or if to the back of a battery switch, or in general, all those places that are normally positive or negative. When in doubt use your meter.
The biggest problem with using a non-obvious color is not at the ends where you normally put labels on. The problem is when you are tracing a cable through bundles or through or under bulkheads, tanks
, etc. That is a problem even if you use the standard colors if you have more than one going in the same general direction. I have used the wire tracing gear
but it is a hassle to set up because you have to disconnect at least one end of the cable and sometimes it just is not sensitive enough or you can't get the probe where you can see it.
What I do is tried and true - I use my eyeballs where I can but even that doesn't help sometimes when you have more than one wire so I almost always go a small section at a time and get a little slack in the cable and tug and pull with my finger on the other side to see/fell which wire I am working on. I triple check this. It can be time consuming and a real PITA. And then I label both ends, and then I draw a diagram to save. I have literally spent hours doing this on mine and other boats.
I have seen, and have used, black heat shrink (to seal the cable) on red wire if that is all I have to denote a negative but this is easy to mix up (or v.v. red heat shrink on a black cable). I like to use red on red and black on black so if I do have one that is different it at least tells me to check it out.