1965 Caravel Electrical System upgrade...need help please.

[teeraniti]

Hi All,
I'm upgrading the electrical system in my '65 Caravel and would like your suggestions and tips for this. The trailer doesn't have converter/charger, only a step-down AC transformer and there's no fuse panel that I know of, only two battery fuses.
Here's an electrical diagram in the trailer's manual:






I'm installing PROGRESSIVE DYNAMICS 9245: 45 AMP CONVERTER and a DC Fuse Box
Here's what I'm planing to do:



I'm bypassing the original manual transfer switches between shore power and battery since I think I don't need it anymore. I'm using 6 AWG wires for all converter, battery and ground wires.
Questions:
1. Where is a good chassis ground area on the trailer, running from a converter and battery? My trailer is not gutted so the inside wall is still intact.
2. On the original manual transfer switches, there's a green polarity light. Do I still need this? If so how can I install it in the new system?
3. How does exterior running lights connect to the trailer's DC system?

Thank you very much for your helps!
Suti

[azflycaster]

#3 is easy, it doesn't. All power to the external running lights as well as the brake and turn lights comes from your truck.

[Inland RV Center, In]

Suti

Remove the complete panel that has the 2 switches, and discard it. Discard, or sell the transformer.

All the hot wires, from the switches, will now go to whatever fuse panel arrangement you come up with.

Ground to the frame with at least a # 10 wire.

Disregard the green light, or keep it of you wisn.

The converter system, has nothing to do with any exterior lights. All the exterior lights should be connected to a 7 way cable, that terminates with the aircraft type round connector pins and sockets.

That cable, then is hooked to the tow vehicle, that provides "ALL" the power for the clearance lights, brake/turn signal lights and back up lights. The tow vehicle, should also provide charging current, for the trailer battery.

You may want to consdier changing all the exterior lights to LED's.

Also, make sure the "breakaway" switch is installed correctly and wired properly.

Andy

[VIKING]

I believe the new convertor may have it's own polarity indicator. Check in the literature for info on that. I also bypassed the shore power switch without a problem.
Remember to not ground the 110v to the chassis, only the 12v. 110v ac runs back to ground through the shore power ground wire.
Rich the Viking

[teeraniti]

Thanks all for your quick replies.
Andy, when you said "Ground to the frame with at least a # 10 wire", do you mean the trailer's frame under the floor or the body/wall?
How do I wire the breakaway switch?
Thanks.

[azflycaster]

The 9245 does not have a polarity indicator, at least mine does not. You can get a small one that plugs into an outlet or continue to use the one you have. I have both.

The breakaway switch is wired with one lead to the trailer battery and the other to hot side of the brakes. It is normally connected to the back of the seven pin connector in your trailer. When the pin is removed, it applies 12 volts to the brake magnets.

[teeraniti]

Thanks, Richard. My converter doesn't have the polarity light either so I may reuse the one I have.
Happy Holidays to you all!
Suti

[Ronald D]

Viking,

I'm getting ready to re-wire my '65 Overlander and am trying to follow everyones direction here on the forums as I know nothing about wiring trailers. My question is; if the 110 volt panel is NOT grounded to the frame of the trailer and a black wire touches the body or frame of the trailer, will the trailer body and frame not be live with 110 volts? If the black 110 volt wire touched onto the frame or the body of the trailer (and the frame was not grounded) wouldn't that put 110 volts onto the ground side of the battery if the battery IS grounded to the frame? Also, if the 110 volt and the 12 volt were both grounded to the frame and or body of the trailer, wouldn't the 12 volts go through the ground conductor to shore power back to where it originates

Ron

[Inland RV Center, In]

Originally Posted by Ronald D

Viking,

I'm getting ready to re-wire my '65 Overlander and am trying to follow everyones direction here on the forums as I know nothing about wiring trailers. My question is; if the 110 volt panel is NOT grounded to the frame of the trailer and a black wire touches the body or frame of the trailer, will the trailer body and frame not be live with 110 volts? If the black 110 volt wire touched onto the frame or the body of the trailer (and the frame was not grounded) wouldn't that put 110 volts onto the ground side of the battery if the battery IS grounded to the frame? Also, if the 110 volt and the 12 volt were both grounded to the frame and or body of the trailer, wouldn't the 12 volts go through the ground conductor to shore power back to where it originates

Ron

Ron.

I would suggest for your safety, that your hire an electrician, pronto.

You cannot talk about the color of wires, since they have no knowledge of what voltage or current you may be running thru them.

I have been involved with electricity and electronics for over 65 years, and you have just confused me. Sorry.

The AC and DC circuits in an Airstream, have nothing to do with each other.

How you treat one, has nothing to do with the other.

Not trying to be harsh, just concerned about your safety, at least when it involves electricity.

Andy

[65CV]

Suti-

If you look at the right side of the window in this picture of the rear of our Caravel, when gutted, you will see a solid copper wire. Follow it down and you can see where it was bonded to the frame. I can't guarantee it was original, but bonding well to the steel frame -- obviously to bare metal somewhere -- is the way to go.

Congrats on getting a Caravel!

John

[Ronald D]

Andy,

I've been a master electrician since 1971, I didn't mean or try to confuse anyone. I am the one confused as I have never wired a trailer with 12 volt and 110 volt power. Rich the Viking stated NOT to ground the 110 volt to the chassis but DO ground the 12 volt to the chassis. If the chassis is not grounded to the shore power and there is a fault, that is; hot wire in contact with the chassis, wouldn't the chassis be live? I believe that in a three wire 110 volt cord there is a black wire (hot) white wire (neutral) and green wire (ground). Unless the chassis was grounded (to the shore power) the fault would have no place to go until someone or something on the ground touched the trailer. Or am I wrong? My other question is IF the shore power cord was grounded to the chassis AND the battery negative was also grounded to the chassis AND there was a fault, wouldn't that put 110 volts on the negative side of the battery, just for and instant? Could that mess up the 12 volt electronics? I'm confused, I just want to do it right.

Thanks,

Ron

[65CV]

Ron-

If you're a Master Electrician, check out Article 551, especially 551.20 of the National Electrical Code. Should answer all of your questions.

John

[teeraniti]

Thanks John for the picture. I'll find a bare metal somewhere in the trailer (possibly the frame under the floor) to make ground connection.
Suti

[VIKING]

Originally Posted by Ronald D

Andy,

I've been a master electrician since 1971, I didn't mean or try to confuse anyone. I am the one confused as I have never wired a trailer with 12 volt and 110 volt power. Rich the Viking stated NOT to ground the 110 volt to the chassis but DO ground the 12 volt to the chassis. If the chassis is not grounded to the shore power and there is a fault, that is; hot wire in contact with the chassis, wouldn't the chassis be live? I believe that in a three wire 110 volt cord there is a black wire (hot) white wire (neutral) and green wire (ground). Unless the chassis was grounded (to the shore power) the fault would have no place to go until someone or something on the ground touched the trailer. Or am I wrong? My other question is IF the shore power cord was grounded to the chassis AND the battery negative was also grounded to the chassis AND there was a fault, wouldn't that put 110 volts on the negative side of the battery, just for and instant? Could that mess up the 12 volt electronics? I'm confused, I just want to do it right.

Thanks,

Ron

I am no electrician, just to be clear.
My understanding is that the 110v system is isolated from the chassis, unless you have a short, or a mis-wired system. The ground for 110v follows the wires, rather than the chassis. The 12v system grounds to the chassis.
Again, I'm no electrician. This is based on what I've read here and seen in my own Airstream. I welcome comments from those with professional experience, as there is no substitute for it, and I would also like to know more about how this works for my own safety.
Best wishes for the hloidays,
Rich the Viking

[Ronald D]

Rich the Viking and John,

I have read 551-20 of NEC. It states that the converter enclosure shall be bonded to the chassis with at least a #8 copper conductor. It also states that the converter be provided with a separate chassis bonding conductor that shall not be used as a current carrying conductor. John, does that sound right?
Rich, If the 110 volt system is isolated from the chassis and a short (fault) or mis-wiring occurs and the chassis becomes energized there is no place for it to go until ground is made, possibly by someone on the ground touching the chassis.

It seems to me that the chassis MUST be grounded. I could be wrong, I just don't understand Airstream wiring.

Retired Ron

[Ronald D]

Rich the Viking,

For your edification the ground wire does NOT carry current back to its source, the white wire does. The ground wire carries fault (short circuit) current back to the distribution panel, eventually through the main breaker to the faulted (short circuited) breaker and trips it. At the speed of light.

Retired Ron

[Jammer]

Ron,

You ask good questions.

Originally Posted by Ronald D

Andy,
Rich the Viking stated NOT to ground the 110 volt to the chassis but DO ground the 12 volt to the chassis. If the chassis is not grounded to the shore power and there is a fault, that is; hot wire in contact with the chassis, wouldn't the chassis be live? I believe that in a three wire 110 volt cord there is a black wire (hot) white wire (neutral) and green wire (ground). Unless the chassis was grounded (to the shore power) the fault would have no place to go until someone or something on the ground touched the trailer. Or am I wrong?

It is my understanding that the green grounding wire from the shore power cord is supposed to be bonded to the trailer frame. However, the service to the trailer is not treated as a service entrance, and therefore the neutral is not bonded to the ground. Matters become more complex in trailers that have a separately derived power source, such as a generator or inverter, because when shore power is not connected, there is no neutral-to-ground bonding point. A result of this is that some transfer switches have the additional components necessary to bond the neutral to ground only when shore power is not present.

My other question is IF the shore power cord was grounded to the chassis AND the battery negative was also grounded to the chassis AND there was a fault, wouldn't that put 110 volts on the negative side of the battery, just for and instant? Could that mess up the 12 volt electronics? I'm confused, I just want to do it right.

The main problem is that not the brief presence of 110 volts on the negative side of the battery (which is inconsequential since the battery has a low series resistance and will maintain a 12 volt nominal DC differential between the +12 volt supply and ground), but rather the fact that there are high impedance components in the frame. As with any ground fault, the high current flow can cause a voltage gradient along the frame components between the fault and the bonding point. So, for example, their might be some AC voltage between the negative side of a 12 volt outlet and the - post on the battery. Yes, it can be enough to damage 12 volt electronics. That is a consequence of using the frame as a 12 volt return, and is lessened by using a wired return to negative bus. Supplying the trailer through a GFCI can limit the fault duration, which also helps.

The best thing to do, from a wiring quality standpoint, is to wire your 12 volt returns the same way as your supplies, rather than running anything to the trailer ground. This is much the same as you would run a wired neutral in a 120 volt system.

[65CV]

Ronald D-

"Is that right?"

I'm not an electrician. My son is an apprentice and is 3/4 of the way through his training. Our Airstream has come up in his class and the answers from his teacher -- a Master Electrician -- sound exactly like Jammer's post.

Here are my takeaways on our discussion of grounding:

(1) the ground on the Airstream has one purpose -- to save your life. Get it right.
(2) Ground the 110v system with #8 or (preferably) #6 wire to the steel frame, not to the aluminum.
(3) Neutral carries as much current as supply. Never connect neutral to ground inside the trailer. It is the responsibility of the supplying system to bond neutral and ground outside of the trailer. They are intended to be separate paths.
(4) Both 12v and 110v systems can be grounded to the chassis.

The more I read about grounding issues, the more concerned I am about some of the trailers out there. I hope that anyone reading this thread makes sure that their neutral and ground are not connected AND they check the polarity of the power supply at the campground. Think about the opposite -- connecting live power to what is assumed to be neutral, then bonding it to the aluminum shell. Proper wiring and polarity testers are cheap insurance.

Here's what I understand about generators. If the trailer is bonded to the ground wire on the supply, you're counting on the generator to be properly grounded or ground fault protected. You may see or hear discussion of driving a rod into the ground and bonding it to the generator -- a little impractical. We're going to count on the Ground-Fault-Interruptor on our new generator and will probably bond ground to neutral on the generator itself. (We will never connect it to the house circuitry.)

Finally -- to repeat -- I am not an electrician. I hope it's helpful to share my conclusions from discussions about my son's training.

John

[Ronald D]

Jammer, I believe that you have it just right. The only reason I got in on this thread was because of Rich the Viking post #4 when he said to NOT GROUND THE CHASSIS.

John, you are also right, your son is paying attention in his classes. The Airstream is treated just like a stove except it is 110 instead of 220, three wires instead of four. The frame is grounded and that ground is NOT connected to the neutral inside the stove. An electrical panel has two buss bars inside, one for the neutral (isolated from the enclosure) and one for the ground which is bonded to the enclosure) The grounding buss is then bonded to the chassis. You say that you're concerned about some of the trailers out there, after seeing post #4, so was I. I hadn't read 551-20 for 40 years, thanks for that information as I knew nothing about 12 volt wiring. All my questions have been answered, especially by Jammer when he says the 12 volt wiring is a 2 wire system, unlike a car that uses the chassis for a return.
Thanks to all, this is my last post ever on this site, I asked what I thought was a simple question and I was met with derision in some quarters. John and Jammer are tops, even Rich the Viking is ok, he was just repeating what someone told him. When he realized his information might be incorrect he asked for clarification. I am now going back into retirement to work on my Overlander, never to look at this site again.

Retired Ron

[Inland RV Center, In]

Originally Posted by Ronald D

Jammer, I believe that you have it just right. The only reason I got in on this thread was because of Rich the Viking post #4 when he said to NOT GROUND THE CHASSIS.

John, you are also right, your son is paying attention in his classes. The Airstream is treated just like a stove except it is 110 instead of 220, three wires instead of four. The frame is grounded and that ground is NOT connected to the neutral inside the stove. An electrical panel has two buss bars inside, one for the neutral (isolated from the enclosure) and one for the ground which is bonded to the enclosure) The grounding buss is then bonded to the chassis. You say that you're concerned about some of the trailers out there, after seeing post #4, so was I. I hadn't read 551-20 for 40 years, thanks for that information as I knew nothing about 12 volt wiring. All my questions have been answered, especially by Jammer when he says the 12 volt wiring is a 2 wire system, unlike a car that uses the chassis for a return.
Thanks to all, this is my last post ever on this site, I asked what I thought was a simple question and I was met with derision in some quarters. John and Jammer are tops, even Rich the Viking is ok, he was just repeating what someone told him. When he realized his information might be incorrect he asked for clarification. I am now going back into retirement to work on my Overlander, never to look at this site again.

Retired Ron

Ron.

All Airstream and Argosy products use a "one wire 12 volt system" and use the chassis and/or shell as the ground return.

They have used that system for over 70 years.

However, in the case of the fiberglass sided Argosy and Land Yachts, then the 2 wire 12 volt system is used, in most places.

The 12 volt DC systems are far removed from the 120 volts AC systems.

Andy