Amp Rating for 12 Volt Wiring

[mre]

I am looking at running two seat heaters (3.5 amps each on the high setting) from separate 12 volt power points. I have been unable to get through to Winnebago to determine what the amp rating is for each plug. I pulled the front fascia plate on the dash to look at the wires connected to the power point. There was some writing on it but I believe the color can tell me the number of amps the power point can handle.

The wire running to the center of the point is a yellow wire coming from a wiring harness and is plugged into a red wire that connects to the center. The wire that attaches to the power point housing is a white wire. Looking at the color code designations for wiring and the wiring length, it appears that I am ok. Any opinions?
thanks
ed

[Gary RVRoamer]

There is no standard color code for 12v wiring, so ignore the colors. Maybe Winnebago has one its uses, but I doubt it. They may have a color they use to indicate the ground side of a circuit, but probably not the amperage of the wire.

The wire to the housing is the ground (12v negative side0 wire and the one to the center is the hot (12v positive).

A typical 12v utility outlet will be rated for 10A, but a few are 15A. Whether the wiring is rated that high is a different question. Find the fuse that serves that yellow hot wire and see what it's rating is. It is supposed to be matched to the current carrying capability of the wiring.

At 3.5A, you are probably ok. The amp capacity of a wire is much greater at 12v than for 120vac, so even 20 gauge will easily handle that amount.

[vsheetz]

Agree, 3.5a should be ok. Find the fuses and check the rating. Check if both power points are not on the same fuse.

[dabrooks]

If you have a fuse panel nearby you can add a new fused circuit by pulling on of the blade fuses and adding one of these. http://www.amazon.com/Support--circu...+fuse+adapters . You can pick the circuit you want to use and put the orignal fuse back in one slot and a new fuse in the other slot that feeds the pigtail. The two fuse do not need to be the same amps. I used the to add cigarette lighter outlets on both sides of the dash. One was added specifically for a heated seat pad.

[flandersdl]

Originally Posted by Gary RVRoamer

The amp capacity of a wire is much greater at 12v than for 120vac, so even 20 gauge will easily handle that amount.

This is not true. The ampacity of wire is determined by NFPA 70 and is the same no matter what the voltage or whether it is AC or DC.

The ampacity of the wire is usually listed on the packs of wire you buy at the auto parts store and is the maximum size fuse that be used to protect the circuit.

Please follow the manufacturer's recommendations to determine the correct size fuse to protect the equipment you are installing.

[mre]

Thanks for taking the time to respond. I guess I will have to try again to get a hold of Winnebago.

ed

[powercat_ras]

Originally Posted by ed rzepka

I am looking at running two seat heaters (3.5 amps each on the high setting) from separate 12 volt power points. I have been unable to get through to Winnebago to determine what the amp rating is for each plug. I pulled the front fascia plate on the dash to look at the wires connected to the power point. There was some writing on it but I believe the color can tell me the number of amps the power point can handle.

The wire running to the center of the point is a yellow wire coming from a wiring harness and is plugged into a red wire that connects to the center. The wire that attaches to the power point housing is a white wire. Looking at the color code designations for wiring and the wiring length, it appears that I am ok. Any opinions?
thanks
ed

You should be fine tapping into a power point to power the seat heaters, you should be able to figure out from the WinnebagoInd.com information or calling them if it's fused 10 A or 15 Amp. Chances are it is 15 Amp fused.

I would put a 5 amp in-line fuse in positive side of the wiring to each seat heater so there is no fire hazard.

There are some common practice used by Winnebago:

1. Wires all have IDs printed on them you can download what the IDs mean on the WinnebagoInd.com web site.

2. White wires are going to in the harness ground wire splices and eventually to chassis ground or one of the negative ground bars. They are always at least 14 gauge, capable of carrying 15 amps. Some are larger as needed for the design of the circuit being carried to ground by the wire, generally the wire from the internal ground wire splice in the harness to a ground point is much larger than 14 gauge.

3. Yellow wires are also at least 14 gauge, the code printed on the wire will identify it's purpose and in many cases will help you tell what circuit breaker or fuse the wire is powered from. Some are larger gauge as needed for the design of the circuit being carried to it's power source.

4. All wires leading to 12 volt power points I have seen on the two Winnebagos I have owned ( 2008 Cambria and 2015 Vista ) are 14 gauge and are fused by 15 amp fuses or breakers.

[alvo]

Winnebago color codes their wiring harnesses to aid in servicing the electrical systems. The colors of each wire used are indicated on the wiring diagrams for each vehicle. That way you can identify both ends of a wire by the color of the wire without having to try to follow it through the walls and ceiling. They even pointed this out in the brochure for the model I have.

[powercat_ras]

Originally Posted by alvo

Winnebago color codes their wiring harnesses to aid in servicing the electrical systems. The colors of each wire used are indicated on the wiring diagrams for each vehicle. That way you can identify both ends of a wire by the color of the wire without having to try to follow it through the walls and ceiling. They even pointed this out in the brochure for the model I have.

In late model Winnebagos they dropped color codes in favor of just using yellow for everything other than negative ground return wires which are white. Everything is yellow but has clear easy to read 3 or 4 letter codes on each wire every few inches. Not color codes but almost as good.

[mre]

Randy & Alvo:

Thanks for taking the time to respond. First let me say that this is not area of expertise. We are on the road now for the summer and I did try to call Winnebago a couple of days ago, but was cut off at 5:00 pm while on hold. I will probably try and call again.

About all have be able to find on the Winnebago website is a diagram showing both 12 volt outlets. One outlet is in the middle of the dashboard on a vertical fascia panel near the bottom a couple of inches above the doghouse. The other is on top of the dash in front of the passenger seat. The diagram shows that both these outlets have been assigned a number (111414-01-000). I could not link them to any breaker on the house 12 volt breaker panel.

The only other thing I could find is in the F-53 owner’s manual referencing to one 20A fuse for a "Cigar Lighter Feed". I don't if this feeds both 12 volt plugs.

By the way. The heated seat is important as I have back problems. After a dealer mistake in 2000, he found a vehicle optioned the way I wanted but also with heated seats. I found that the heated seat sooth an aching back and all out vehicles have had them. I use the heated seats year round turning them on and off as needed. Our MH does not come with them and hence my interest in seat heaters.

[TQ60]

Wire size determines capacity of the wire and fuse should be determined by device or wire whichever is smaller.

The modern lighter outlets ate NOT the same as past.

In the past they were real and drew much current so they were built more robust.

Current use is for cell phones and other low power devices so the quality of the connections not so good any more.

For a seat heater or other higher current device you can use the existing to see if the device fills the need but for a long term install add a new connection on a dedicated fuse do you have a known good circuit and less risk of overload on other one.

A 4 amp load is minimal but could be too much for the installed circuit if it is continuous duty.

4 amps is only 48 watts or so which is not much heat.

[tropical36]

Originally Posted by ed rzepka

I am looking at running two seat heaters (3.5 amps each on the high setting) from separate 12 volt power points. I have been unable to get through to Winnebago to determine what the amp rating is for each plug. I pulled the front fascia plate on the dash to look at the wires connected to the power point. There was some writing on it but I believe the color can tell me the number of amps the power point can handle.

The wire running to the center of the point is a yellow wire coming from a wiring harness and is plugged into a red wire that connects to the center. The wire that attaches to the power point housing is a white wire. Looking at the color code designations for wiring and the wiring length, it appears that I am ok. Any opinions?
thanks
ed

First, let me say that the amount of amperage draw quoted sounds extremely low for any kind of a 12v heater.
Having said that, the voltage has nothing to do with it, generally speaking and is only associated with it's running current.
Most charts with wiring types in general, that refer to conduit runs, bundles or in a sheath at 86 F are as follows....
#18 - 5amps
#16 - 10amps
#14 - 15amps
#12 - 20amps
Open air runs in freezing temps and certain types of wire insulation will carry a lot more.
Sticking with the above is always best for the do it yourselfer and the fuse or breaker should be sized accordingly to protect the wire.

[mre]

I got an answer (email) back from Winnebago about he 12 volt plugs. In my question, I also ask if each plug was on it's own circuit the breaker/fuse. This is the answer I got.

"That will be tied into a 15 amp breaker that is located on the floor left of the steering column. "


I am taking that to mean both are on the same circuit. I looked at the circuit and there is no breaker designated specifically for the two 12 volt plugs, only a 15 amp breaker that says "MISC (COACH)". I am assuming that is it. The only other breaker that is not specifically designated is a 25 amp that say "MISC (CHASSIS)".

I decided to try and trip the 15 amp breaker to be sure that it is the one that powers the two 12 volt plugs. These breakers are cylindrical and have a button in the middle that pops if there is an electrical issue. I have never seen these before. I tried and pushed the center button but it won't pop out. Any ideas?

Thanks
ed

[tropical36]

Originally Posted by ed rzepka

I got an answer (email) back from Winnebago about he 12 volt plugs. In my question, I also ask if each plug was on it's own circuit the breaker/fuse. This is the answer I got.

"That will be tied into a 15 amp breaker that is located on the floor left of the steering column. "


I am taking that to mean both are on the same circuit. I looked at the circuit and there is no breaker designated specifically for the two 12 volt plugs, only a 15 amp breaker that says "MISC (COACH)". I am assuming that is it. The only other breaker that is not specifically designated is a 25 amp that say "MISC (CHASSIS)".

I decided to try and trip the 15 amp breaker to be sure that it is the one that powers the two 12 volt plugs. These breakers are cylindrical and have a button in the middle that pops if there is an electrical issue. I have never seen these before. I tried and pushed the center button but it won't pop out. Any ideas?

Thanks
ed

The breaker marked chassis could be for the 12vdc dash outlet, like on any other vehicle.
The breaker marked Coach could be for a house outlet.
I don't think these breakers are designed to be manually tripped and not as if it was GFI protected.