12v and 110 - Wired together?

[KellySLC]

Hi all,

This may seem like an obvious question but it seems like everything in my Caravel was wired with Romex and very little 12v stranded wire. I did not take pics when we removed it (big mistake, teenagers stole camera), and I don't know how it should go back.

We bought a bunch of 10 awg stranded wire and we have a roll of 12/2 romex. In looking at the owners manual, it sounds like all lights and systems can work on either 12v or 110 at the flip of a switch - except for the fridge, plugs and AC. Does the 12v and 110 run on the same wire?

Should I be running 1 - 10g stranded 12v line AND 1 - 12/2 romex 110 line together to all the lights and stove fan (I'm piggy backing them but running the water pump, radio/12v outlets, fantastic fan and furnace on separate circuits)? I don't remember there being that many wires inside the light fixtures when I took them out.

I have a huge spool of high quality, stranded 10g and currently have 2 wires running the length of each of the circuits I've run. Do I also run a romex run to everything before I button it up?

I'm still reading the forums to try to educate myself, but this particular one has a severe learning curve if you screw up.

Thanks!

Kelly

[wmarsha]

kelly ya ought to get a service manual showing the two different wiring schematics. then, run 12 ga romex for the 120vac 20amp circuits. Romex is solid wire. Run stranded automotive type wire the correct gauge for the 12vdc circuits-use plenty of colors, and markers for the ends. it looks like a rats nest, but once you figger out what's happening, it is fairly straight forward.

[wmarsha]

in my a/s the receptacles (outlets) are, of course 120vac. All the hardwired lights are 12vdc. the only 120vac lights in my a/s plug into a receptacle. The air conditioner is the only thing in my a/s that is hard wired 120vac. Well, I really haven't had the micro/convection oven out, but in my last coach the micro was a plug in unit. Even the battery converter/charger is a plug in unit. that should help a little, i hope. -------------------------------------------- ah phooey, i hope i am not confusing you. all the fans in my coach are also 12vdc. the water pump is also 12vdc. everything in the coach EXCEPT the air conditioner, micro/convect oven, refer and battery charger is powered by 12vdc. Even the refer plugs in. -------------------------------------- I'm gonna go on a limb here, as I really do not know the older a/s, but they MAY have used 2 wire romex for both ac and dc circuitry. today, you want to use 3 wire romex (12-2 with ground, minimum) for the 120vac circuits, and a colored (+12vdc) and a black (-12vdc) paired for each light, fan, pump, etc. (some will say white for the -12vdc, but for most vehicles, black is the color of the -12vdc lead). ------------------------------------------ The only place the two systems (AC and DC) connect is the grounding conductors are all connected or bonded to the frame of the coach. You should have a 10ga bare copper wire near the AC dist box connected to the frame, and of course the big leads of the batteries are connected to the frame. there is also a grounding conductor from the battery charger that connects to frame, separate from the negative battery lead. again on my coach there are two connections to the frame up front near the 12vdc distribution and there is one connection to the frame at the back near the AC distribution. -------------------------------------------- and yes, i am sure on the older coaches, the grounding conductors for the ac service were undersized compared to today's requirements, but a 30 amp service requires a 10ga copper grounding conductor.

[Jammer]

Kelly

There are two schools of thought.

Older airstreams were wired so that most of the lights and the bathroom fan could run on either 120v or 12v. For the lights, for example, the fixtures had two bulbs, a 12v bulb and a 120v bulb, and there was a switch for each light that allowed you to select which power source to use. In those days there were no converters so if you had shore power you wanted to conserve the 12 volt battery power, because that would only recharge from the tow vehicle, and slowly at that.

The bathroom fan is wired similarly except that instead of a separate 120 volt motor, it has a transformer.

So, one school of thought is to maintain that. Separate 12v and 120v wiring would then be required.

More recent trailers, after 196x, have the "univolt" system, where all the lights and the fan motor all run on 12 volt, and there is a converter so that the battery will charge and 12v power will be available when shore power is connected. This system doesn't involve as much wiring, or the unusual and complicated dual-lamp fixtures.

Most people, when restoring a trailer, switch to the "univolt" system and abandon or remove the 120v wiring to the lights. A few retain the original dual system.

The choice is yours.

[KellySLC]

Wow... excellent responses! Thank you both!

Jammer - I don't think my '65 had the dual lights as you describe. I had a mobile RV guy look at the electrical after I had the skins off, but he wanted $$$ to do anything and I thought it would be better if I understood what was happening before just having some guy (who apparently hates airstreams) tear it apart. He was shocked to see romex everywhere and neither of us knew what was AC and what was DC since it was all romex except a 12g wire which was run to the switch for the water pump.

I am using a converter - bought a 55 amp intellipower unit.

So, to both you and banjobill... If I run 2 - 10g stranded wires, for example, to the farthest light and then to each light in that circuit, all the way back to where my electrical boxes/bateries will be, that's all I need to do to run the wire? ...one wire for the neg on the lights, one wire for the pos, and no ground wire?

My final light on the circuit is a 'scare' light I added (from vintage) that only has one little green wire coming out the back and no instructions. Assuming I hook the + to the green wire, what do I do with the black wire?

I'm not going to try to actually connect the converter/batteries, etc., myself I just want to save some $$ by running the wires.

I also want to run a wire to where an A/C unit could go, and for future solar while its all open.

Should the A/C and solar wires be heavier than 10g?

I know I'm asking a lot of questions, but I REALLY appreciate your help here. It will actually be doubly helpful since I'll be bustin' into the '49 pretty soon too.

Thanks again!

Kelly

[47WeeWind]

Originally Posted by KellySLC

Hi all,

1. Does the 12v and 110 run on the same wire?

1A. No. 12 volts d.c. (VDC) and 110 volts AC (VAC) use separate circuits and separate wires. Keep them separate. In your 1965 Caravel, all the lights, stove fan, radio, 12 volt outlets, furnace (maybe, maybe not ??) and water pump ran on 12 volts. Wire them 12 VDC only when rewiring.

Assuming your Caravel has not been upgraded electrically, when your switch was set to "shore power" and your trailer was plugged into 110 volts, an old transformer (the Univolt for your 1965 Caravel) stepped down the 110 VAC to 18.9 VAC, which ran all the 12 volt stuff (it's magic but worked -- back then the dumb 12 volt stuff accepted 18.9 VAC as if it were 12 VDC).

When you switch was set to "battery power", then the 12 volt stuff ran off your 12 volt battery. But your old Univolt, being just a transformer without a rectifier [which changes AC to DC], never charged your battery.

Today, discard your old Univolt; its obsolete and never charged your 12 volt battery in any event. It only ran your 12 volt stuff on 18.9 VAC when you were plugged in and the switch was set of "shore power". Get rid of that "shore power" battery power" switch but keep the circuit breakers behind it and use them to protect your 12 volt circuits.

Buy a Progressive Dynamics Intelipower 3 stage battery charge/converter with Charge Wizard (or another brand of smart 3 stage battery charger) and install that in place of the Univolt. Now your 12 VDC will be true 12 VDC.

Plug the Intellipower (or other brand) into a new 110 volt AC dual outlet you install nearby using the former 110 VAC wire was dedicated to and went to the Univolt. After doing that, now when the trailer is plugged into 110 volts at home or at a campground, the battery will run all the 12 volt appliances, lights, etc. and the Intelipower will charge the battery so it doesn't get run down. When not plugged in to 110 VAC, the battery will still power all the 12 volt stuff but it will eventually run down because it is not being refreshed. Some people install solar panels or use a Honda/Yamaha generator to recharge the battery.

Originally Posted by Kelly SLC

2. Should I be running 1 - 10g stranded 12v line AND 1 - 12/2 romex 110 line together to all the lights and stove fan (I'm piggy backing them but running the water pump, radio/12v outlets, fantastic fan and furnace on separate circuits)?

2A No. Just run two 12 volt wires to all your 12 volt stuff, one hot (+) and the other ground (-).

Originally Posted by Kelly SLC

3. I don't remember there being that many wires inside the light fixtures when I took them out.

3A. Good memory! Your 1965 Caravel never had dual voltage (both 12 VDC and 110 VAC) light fixtures or any other dual voltage appliances. Toss that concept out of your mind. Only Airstream built from ~ 1958 to 1963 had dual voltage fixtures. All light fixtures, fans and motors (except for air conditioner motors and compressors) ran on 12 volts only beginning in 1964.

Originally Posted by Kelly SLC

4. I have a huge spool of high quality, stranded 10g and currently have 2 wires running the length of each of the circuits I've run. Do I also run a romex run to everything before I button it up?

4A. No. Keep all 12 VDC circuits 12 volts and wire them you your stranded 10g wire; keep the few 110 VAC circuits (mostly to AC outlets) 110 volts and wire them with romex. [Your outside light above the door might be 110 VAC instead of 12 VDC, so beware of that possible exception]. But test all the 12 volt circuits and all 110 VAC outlets separately before you reinstall the interior walls.

Originally Posted by Kelly SLC

5. I'm still reading the forums to try to educate myself, but this particular one has a severe learning curve if you screw up. Thanks! Kelly

5A. All 1964 and just the short 1965 Airstreams like your Caravel used an AC transformers (called the Univolt those years -- be aware that "Univolts" changed in function, operation and specifications over the decades notwithstanding keeping a common trade name) to power the DC stuff when plugged into shore power, so that extremely unusual use of electricity would make anyone's head ache big time. You are smart to ask first. Have fun!

[47WeeWind]

Originally Posted by KellySLC

1. . . . Jammer - I don't think my '65 had the dual lights as you describe. I had a mobile RV guy look at the electrical after I had the skins off, but he wanted $$$ to do anything and I thought it would be better if I understood what was happening before just having some guy (who apparently hates airstreams) tear it apart. He was shocked to see romex everywhere and neither of us knew what was AC and what was DC since it was all romex except a 12g wire which was run to the switch for the water pump.

1A. Your trailer never had dual voltage fixtures. The 12 VDC wires may have been run inside romex, or maybe Airstream just used romex for separate 12 volt circuits as a way to protect the wires.

Originally Posted by KellySLC

2. I am using a converter - bought a 55 amp intellipower unit.

2A. Excellent! You are a step ahead already.

Originally Posted by KellySLC

3. So, to both you and banjobill... If I run 2 - 10g stranded wires, for example, to the farthest light and then to each light in that circuit, all the way back to where my electrical boxes/bateries will be, that's all I need to do to run the wire? ...one wire for the neg on the lights, one wire for the pos, and no ground wire?

3A. Yes, one wire for 12 volt positive (+) and another for 12 volt negative (-). Don't ground your 12 volt circuits to the trailer. For better results, don't use your trailer body/frame as the return 12 volt negative path. Instead, install a separate wire for 12 volt negative and run it (more than one 12 volt appliance can be OK on the same 12 volt negative circuit) to the negative terminal on the battery.

Originally Posted by KellySLC

4. My final light on the circuit is a 'scare' light I added (from vintage) that only has one little green wire coming out the back and no instructions. Assuming I hook the + to the green wire, what do I do with the black wire?

4A. Attach the scare light black wire to a negative 12 volt wire in your nearest 12 volt circuit.

Originally Posted by KellySLC

5. I'm not going to try to actually connect the converter/batteries, etc., myself I just want to save some $$ by running the wires. I also want to run a wire to where an A/C unit could go, and for future solar while its all open.

5A. OK. Good planning ahead.

Originally Posted by KellySLC

6. Should the A/C and solar wires be heavier than 10g?

6A. I don't know. Someone with a newer trailer, and someone with good solar panel installation experience, will have to answer those questions for you. Search for a recent posting (today or yesterday) from "Lewster" on solar panel-to-controller wiring gauge.

Originally Posted by KellySLC

7. I know I'm asking a lot of questions, but I REALLY appreciate your help here. It will actually be doubly helpful since I'll be bustin' into the '49 pretty soon too. Thanks again! Kelly

7A. This will be good training, as you can wire the '49 the same way.

[KellySLC]

Once again Fred - THANK YOU! It's finally making sense...

QUOTE: 4A. Attach the scare light black wire to a negative 12 volt wire in your nearest 12 volt circuit.

On the scare light - That light is the last fixture in the series (the wiring on the run terminates into that fixture). You're saying I should instead terminate the black (-) wire at the last fixture before the scare light on the same circuit? I've been told the scare light is self-grounding to it's frame, thus into the trailer body into which it's mounted. Actually, the last 'fixture' will be the switch to the scare light since it didn't come with one.

OR should I continue the black (-) wire past the scare light and connect it to the black (-) of the radio/12v outlet circuit (the nearest separate circuit), such that one of them has two blacks and one white wire? Thanks for walking me through this!

Kelly

[47WeeWind]

Originally Posted by KellySLC

Once again Fred - THANK YOU! It's finally making sense...

QUOTE: 4A. Attach the scare light black wire to a negative 12 volt wire in your nearest 12 volt circuit.

On the scare light - That light is the last fixture in the series (the wiring on the run terminates into that fixture). You're saying I should instead terminate the black (-) wire at the last fixture before the scare light on the same circuit? I've been told the scare light is self-grounding to it's frame, thus into the trailer body into which it's mounted. Actually, the last 'fixture' will be the switch to the scare light since it didn't come with one.

OR should I continue the black (-) wire past the scare light and connect it to the black (-) of the radio/12v outlet circuit (the nearest separate circuit), such that one of them has two blacks and one white wire? Thanks for walking me through this! Kelly

Hi Kelly:

Your scare light has only one green (+) wire coming out of it, and no black (-) wire for grounding. Make the scare light (+) wire the last connection of the 12 volt (+) wire on the circuit that powers the stove fan [here I'm assuming the 12 volt circuit from the stove fan is the closest 12 volt circuit to your scare light excluding the radio 12 volt circuit -- see below]. Don't count on self-grounding alone of the scare light housing for the (-) connection. We want to strengthen it.

Extend the (-) wire from the stove fan to the scare light housing and crimp on a closed loop wire terminal that has a hole the same size as the hole in the scare light mounting flange. Clean or rough up the interior skin around one of the scare light mounting holes you select. Place a toothed or small lock washer against the skin (to assure a good grounding connection) then place the (-) wire terminal on top of the washer. Put the connector from outside the trailer (rivet, bolt and nut, or sheet metal screw) though the washer and crimped-on wire terminal before tightening the connector. This will provide a stronger ground direct from the battery to the scare light housing via the connector. When doing this, you must then put the scare light switch in the (+) wire to the scare light to assure its completely disconnected when switched off.
.
Put the scare light switch in the (+) wire to scare light, somewhere between the stove fan (+) terminal and the scare light (+) terminal (green wire). Even though the (+) wire to the switch might physically extend beyond the scare light housing and circle back to the scare light, electrically the scare light switch is still "between" the (+) connection on the stove and the (+) connection on the scare light. The physical relationship of the location of the scare light housing to its switch is simply "shorthand" and is irrelevant. Its the position in the electrical circuit that is important.

Don't use the radio's (-) wire to ground the scare light and don't use the radio's (+) wire to power the scare light. The radio is wired on its own separate dedicated 12 volt circuit directly from the battery to provide the radio with "clean" 12 volt power that is not polluted by any electrical noise, hum, interference or static from any light, fan or motor on the same circuit. Continue that practice is your '65 Caravel.

Have fun!

[NavyDavesCvl]

Does anyone have any pictures?

[bwaysteve]

WeeWind,
So there is no need for 3 wire Romex?Is stranded(as used in boats) necessary?
What a great explanation of the basic set up!
This is actually my next project on my 65 Ambie. Thank you

[NavyDavesCvl]

How about...Is there any body in Southwestern New York that could honestly get my lights working again?

[gwchitty]

Some clarifications:

1. The univolt transformer takes in 120vac and has two outlet wires - one 12vac and one 18vac. The lights all work on 12vac and the fans and pump motors ran on 18vac. This is why there are two switches on the univolt. The motors and the lamps also run on 12vdc from the battery. All this because the motors run slower on ac than dc.

2. The original wiring in my Caravel: The 120vac wiring is 3 conductor romex, probably 14g. The 12vdc is a 2 conductor romex (no bare wire) about 12 g. Solid wire has a lower resistance than stranded wire of the same Gage. The only stranded wire is in the third circuit - the tow vehicle powered tail lights, brake system wires, and battery charge wires.

3. There is a simple wiring diagram that can show all this in the 65 caravel owners manual. This has been posted elsewhere but I can send you a copy if you pm me.

4. My scare light is wired off the nearby cone light. 12vdc thru a switch so you can use it when on battery power.

5. Don't forget to use rubber or plastic grommets to protect wires going thru metal studs.

Cosmos

[C Johnson]

Originally Posted by cosmos

Some clarifications:

1. The univolt transformer takes in 120vac and has two outlet wires - one 12vac and one 18vac. The lights all work on 12vac and the fans and pump motors ran on 18vac. This is why there are two switches on the univolt. The motors and the lamps also run on 12vdc from the battery. All this because the motors run slower on ac than dc.

2. The original wiring in my Caravel: The 120vac wiring is 3 conductor romex, probably 14g. The 12vdc is a 2 conductor romex (no bare wire) about 12 g. Solid wire has a lower resistance than stranded wire of the same Gage. The only stranded wire is in the third circuit - the tow vehicle powered tail lights, brake system wires, and battery charge wires.

3. There is a simple wiring diagram that can show all this in the 65 caravel owners manual. This has been posted elsewhere but I can send you a copy if you pm me.

4. My scare light is wired off the nearby cone light. 12vdc thru a switch so you can use it when on battery power.

5. Don't forget to use rubber or plastic grommets to protect wires going thru metal studs.

Cosmos

Bingo ! oh and ditto also.