Red wire, black wire and white wires

[swimmer_spe]

I am hooking my battery to my trailer. I have 2 sets of cables. One has a white and a black wire. The other has a white and red wire. Which is negative and positive? I don't now, and when I hooked them up, I may have crossed them.

The trailer is a 1975, so there are no circuit boards to fry.

[MEXICOWANDERER]

Send someone to the scrap seller and purchase that big roll of brown.

[CA_Traveler]

swimmer_spe wrote:

CA Traveler wrote:
Ohm test is a start but may not be adequate and yield low ohms on both - and + wires. The option I use is a series load and I've used a light bulb as suggested. You may need a load that draws more amps and find and turn off switches etc that could lead to false conclusions on the positive side.

Once the weres are connected With a 50 year old RV it would also be a good idea to leave a heavy draw load in series while while you turn on and test everything inside with the view that the series load will have a voltage drop.

That second set of wires could also be for trailer brakes.

The trailer brakes makes sense.... So, is there a common wire code for them?

No, not to mention the RV mfg added wire.

Think of it this way: There may be a recommendation but there is no standard or inspection requirement. And you're the mfg floor manager and you ran out of black wire but have a ton of pink wire. What do you do?

[swimmer_spe]

CA Traveler wrote:
Ohm test is a start but may not be adequate and yield low ohms on both - and + wires. The option I use is a series load and I've used a light bulb as suggested. You may need a load that draws more amps and find and turn off switches etc that could lead to false conclusions on the positive side.

Once the weres are connected With a 50 year old RV it would also be a good idea to leave a heavy draw load in series while while you turn on and test everything inside with the view that the series load will have a voltage drop.

That second set of wires could also be for trailer brakes.

The trailer brakes makes sense.... So, is there a common wire code for them?

[CA_Traveler]

Ohm test is a start but may not be adequate and yield low ohms on both - and + wires. The option I use is a series load and I've used a light bulb as suggested. You may need a load that draws more amps and find and turn off switches etc that could lead to false conclusions on the positive side.

Once the weres are connected With a 50 year old RV it would also be a good idea to leave a heavy draw load in series while while you turn on and test everything inside with the view that the series load will have a voltage drop.

That second set of wires could also be for trailer brakes.

[swimmer_spe]

Bobbo wrote:

Boon Docker wrote:
Set your multimeter to ohms. Ground one probe to the frame then touch the other probe to each wire separately.
A reading of zero to 1 ohm means that wire is negative.

Be sure that no wires are connected to the battery's positive terminal. Touch a hot wire like this and you will damage the meter.

I know how to use one. I was hoping that it would have been simple as white is always ... The idea of the ohm test on the frame and wires will help.

[swimmer_spe]

Boon Docker wrote:
Set your multimeter to ohms. Ground one probe to the frame then touch the other probe to each wire separately.
A reading of zero to 1 ohm means that wire is negative.

Great idea! I never thought of that.

[RJsfishin]

I believe there is a sorta standard. For 40 yrs, every 12v assesory you will ever buy has either black and white, or red and black for power. The red and black is always pos. I call that a sorta std. If you would install a black/white cable using the white as pos it would be wrong. Same w/ a red/black cable, a black pos would be wrong !

[Bobbo]

Boon Docker wrote:
Set your multimeter to ohms. Ground one probe to the frame then touch the other probe to each wire separately.
A reading of zero to 1 ohm means that wire is negative.

Be sure that no wires are connected to the battery's positive terminal. Touch a hot wire like this and you will damage the meter.

[Boon_Docker]

Set your multimeter to ohms. Ground one probe to the frame then touch the other probe to each wire separately.
A reading of zero to 1 ohm means that wire is negative.

[swimmer_spe]

OP here.

A few things...

1) No shore power available there. So, that test is out.

2) No power jack.

3) I do have my truck, so plugging in the wire will work. I also own a multimeter, but I was hopeful that there was some sort of standard....

[JaxDad]

It seems a few folks are over thinking this.

Take a 12 volt light bulb and some scraps of wire, connect one side of the light bulb to the positive battery terminal and start connecting wires to the other side of the light bulb. Negative (ground) wires will make the bulb glow brightly, a very faint glow or no light at all means you have a positive wire.

[naturist]

Given that it is easy for a 45 year old trailer to have non-standard wire colors, you will find a VOM to be essential to figuring anything out, and that will call for someone who understands electricity too. If you lack either the tool or the understanding, it's a crapshoot with very high odds of bad, bad juju and a very high probability of letting the magic smoke out. My advice is don't attempt it yourself. Get somebody there, on the ground, VOM in hand to help you.

[wapiticountry]

CA Traveler wrote:
The tape is 3M Scotch 35 and comes in a various colors.

The best black tape I've ever used bar none is 3M Scotch Super 88.

These are vinyl electrical tape.

I use heat shrink on new projects when the wire ends are available.

Vote #2 for Super 88. That is one product where paying premium prices is actually a bargain.

[2oldman]

Turn everything off. Hook up what you think is right. Turn on a fan. If it runs backwards, reverse wires.