Need Positive Busbar Explanation

[MSL]

I recently installed a Victron BMV-712, SmartSolar, and Orion XS. Everything went well and is working as expecting, but I realized afterward that the positive busbar is not just a connection point like the negative; it incorporates breakers, most likely of different ratings. I feel like a moron for not thinking about this when I saw the copper bar, but I didn't.

I also re-did most of the Airstream connections as I could see they cut some wire strands when stripping and also didn't have all the strands that were left inserted into the busbar properly. Where possible, I re-did these with ferrules.

I'm hoping I didn't inadvertently connect a wire to the wrong terminal. I have "before" pics I can look at, but I'm not at the trailer now so can't check everything. Also, an explanation of its function and how it's supposed to be wired would be very helpful. I tried looking online for something, but I can't even find a busbar like what's in my trailer.

All comments and thoughts will be very much appreciated.

Thanks in advance, Mark

[BGClassic]

MSL,

It's all part of the learning process. I went through this last year at this time when I added my MP-II, and added batteries, moved them inside. I had a lot of project creep, as I found a lot of loose cables in lugs, cables too long, etc. I found this picture of a similar 12V distribution box, and it helped me. I labeled mine. I recommend you get the electrical drawing package (pdf) from Airstream for your rig. Trace out every wire.

You are right about the circuit breakers (CB). It depends on which side of the breaker you attach wires.

Once you finish your mods, put together a drawing package to document the install. As others on this forum have said, you will then know how it works and be able to troubleshoot when something fails, or you line up something incorrectly!

Good luck!

[OrangeCrush]

Those are Bussman auto reset breakers. I personally don't like them as they are not really safe which is why they are banned in aircraft. They trip based on thermal overload but then they automatically reset once the overload is gone and thermally recovered so if you have a short circuit they just go off-on-off-on... I replaced all of mine with a blue sea fuse bank which is what many people do.

[waninae39]

i use the copper busbar with my 4 LION batteries on the BLACK side
on the RED side i use 0/4 copper wires to connect the the fuses

[JeffKim]

@BG has them labeled really well and that's the way they are in our 2023 25' GT. I had no idea they existed either, the only place I have found them is in the wiring diagram in the owner's manual. With a PDF I can blow up that part and get the amps. It might be different with your trailer. I had the 50A coming from the charger (labeled switch in diagram) go bonkers one time, it would trip at lower and lower amps and had to replace it. Yes, makes sense to put in fuses instead.

[MSL]

Originally Posted by BGClassic

MSL,

It's all part of the learning process. I went through this last year at this time when I added my MP-II, and added batteries, moved them inside. I had a lot of project creep, as I found a lot of loose cables in lugs, cables too long, etc. I found this picture of a similar 12V distribution box, and it helped me. I labeled mine. I recommend you get the electrical drawing package (pdf) from Airstream for your rig. Trace out every wire.

You are right about the circuit breakers (CB). It depends on which side of the breaker you attach wires.

Once you finish your mods, put together a drawing package to document the install. As others on this forum have said, you will then know how it works and be able to troubleshoot when something fails, or you line up something incorrectly!

Good luck!

Thanks. This photo is helpful.

One thing I want to confirm: My solar positive wire from the SunExplorer II was originally connected to one of the copper bar terminals, so I connected to the same terminal with the positive from the SmartSolar charger. I also did the same with the Orion XS, which seems to make sense to me.

I did mark a bunch of the wires as I was doing these installations. I didn't shorten or neaten up much, because I wanted to just get everything connected. I think this summer will be a good time to "organize" all of that wiring. Airstream really does a messy job with that.

The other thing I did was vacuum up as much of the debris Airstream left behind. I have to admit, their assembly process is very unprofessional.

Anyway, thanks very much for the reply.

Mark

[BGClassic]

JeffKim,

That's not my 12V box, but mine (Classic) is close. I found it online. We all start somewhere.

I did not know these Bussmans were banned in aircraft. Maybe I will replace mine. I did change some things in that box, and I replaced the 12V ground buss with a Blue Sea Systems buss, since the original buss bar had a wire that fell out, and the screws are not secure, and nearly impossible to access.

I added a Lynx distribution unit, and have added stand-alone fuseblocks as well.

[MSL]

Originally Posted by OrangeCrush

Those are Bussman auto reset breakers. I personally don't like them as they are not really safe which is why they are banned in aircraft. They trip based on thermal overload but then they automatically reset once the overload is gone and thermally recovered so if you have a short circuit they just go off-on-off-on... I replaced all of mine with a blue sea fuse bank which is what many people do.

Thanks for this. I see now they're actually separate breakers attached to the bar; I hadn't realized that.

Any chance you can share a link to the fuse bank you used?

Many thanks,

Mark

[MSL]

Originally Posted by JeffKim

@BG has them labeled really well and that's the way they are in our 2023 25' GT. I had no idea they existed either, the only place I have found them is in the wiring diagram in the owner's manual. With a PDF I can blow up that part and get the amps. It might be different with your trailer. I had the 50A coming from the charger (labeled switch in diagram) go bonkers one time, it would trip at lower and lower amps and had to replace it. Yes, makes sense to put in fuses instead.

Thanks. This is also helpful.

I called Airstream and had them send me my electrical schematics this morning.

Mark

[MSL]

Originally Posted by BGClassic

JeffKim,

That's not my 12V box, but mine (Classic) is close. I found it online. We all start somewhere.

I did not know these Bussmans were banned in aircraft. Maybe I will replace mine. I did change some things in that box, and I replaced the 12V ground buss with a Blue Sea Systems buss, since the original buss bar had a wire that fell out, and the screws are not secure, and nearly impossible to access.

I added a Lynx distribution unit, and have added stand-alone fuseblocks as well.

The 2019 Sport 22 doesn't even use a box; they just throw it all in there.

Mark

[JeffKim]

Originally Posted by BGClassic

I replaced the 12V ground buss with a Blue Sea Systems buss, since the original buss bar had a wire that fell out, and the screws are not secure, and nearly impossible to access.

Sounds like the same bus bar that I got. Impossible to reach, so if I feel ambitious maybe I'll replace it also.

[BGClassic]

Originally Posted by MSL

The 2019 Sport 22 doesn't even use a box; they just throw it all in there.

Mark

I had no idea! Take a look at the Blue Sea Systems web site. They have lots of cool, good quality stuff.

[BGClassic]

Originally Posted by JeffKim

Sounds like the same bus bar that I got. Impossible to reach, so if I feel ambitious maybe I'll replace it also.

It was a bear to access. I destroyed a sweatshirt in the process of crawling into my front storage locker over the LP tank supports. Then sorting out the rat's nest of wires and re-terminating them.

[OrangeCrush]

Originally Posted by MSL

Thanks for this. I see now they're actually separate breakers attached to the bar; I hadn't realized that.

Any chance you can share a link to the fuse bank you used?

Many thanks,

Mark

Below is a link to the one I used along with a link to my schematic showing how it was used. It was part of a complete solar/lithium/inverter install so you may want to use something different depending on what you are doing. As BGClassic points out they have lots of things to choose from on their website and many can be ordered on Amazon.

https://www.bluesea.com/products/504...s_-_8_Circuits
https://drive.google.com/file/d/1Utg...ew?usp=sharing

I think the reason Airstream uses the auto reset Short Stop breakers is they like to bury that bus bar with no thought put into end user access. If you replace them with fuses or manual reset breakers you need to make sure you can get to it somewhat easily.

[MSL]

Below is a photo before I installed the Victron BMV-712, SmartSolar, and Orion XS (and before I vacuumed).

I understand:
- The power comes in from the battery and connects to the copper bar thru a 50 amp breaker.
- The power goes out to the disconnect switch then to the DC distribution thru a 50 amp breaker.
- The propane detector has its own fuse as it doesn't go thru a breaker.
- The break-away (brake) switch connection goes thru its breaker.
- I know the line connection is supposed to be connected to the copper terminal.

Questions:
- These breakers must work in both directions, otherwise the solar wouldn't be getting power to the battery, correct?
- Why would the +12-volt connection from the 7-pin be connected to the copper bar thru a breaker and not directly to it?
- Should my OrionXS positive charge connection go right next to the solar connection?
- I ran a 12-gauge pair to under my battery box to connect a small air compressor. I assume the positive connection should be connected to the copper bar with an inline fuse, correct?

Thanks for all comments.

Mark

[MSL]

Originally Posted by OrangeCrush

Below is a link to the one I used along with a link to my schematic showing how it was used. It was part of a complete solar/lithium/inverter install so you may want to use something different depending on what you are doing. As BGClassic points out they have lots of things to choose from on their website and many can be ordered on Amazon.

https://www.bluesea.com/products/504...s_-_8_Circuits
https://drive.google.com/file/d/1Utg...ew?usp=sharing

I think the reason Airstream uses the auto reset Short Stop breakers is they like to bury that bus bar with no thought put into end user access. If you replace them with fuses or manual reset breakers you need to make sure you can get to it somewhat easily.

Thanks for this. I'm hoping to clean up the wiring in the summer, and will consider the fuse block then.

Very nice work and diagram! When I'm done, I'm going to create one.

Thanks again, Mark

[JeffKim]

Originally Posted by MSL

Questions:
- These breakers must work in both directions, otherwise the solar wouldn't be getting power to the battery, correct?
- Why would the +12-volt connection from the 7-pin be connected to the copper bar thru a breaker and not directly to it?
- Should my OrionXS positive charge connection go right next to the solar connection?
- I ran a 12-gauge pair to under my battery box to connect a small air compressor. I assume the positive connection should be connected to the copper bar with an inline fuse, correct?

Thanks for all comments.

Mark

I forgot, with our dearly departed 2021 16' Bambi everything was a jumble without any box. Maybe a little better than what you have.

I'll take a swing at these:

1. Yes, breakers work in both directions.
2. You're asking why the brakes have a breaker? I'd guess that if the brakes short out or something it doesn't burn up the wire going to them or something?
3. I put a fuse on the XS output to the positive bus bar. My system is different since there's a Lynx installed which acts as a fuse box. So it's wired to the Lynx which goes to the bus bar.
4. Yes, I'd fuse it. The fuse protects the wire, so the rule of thumb is to put the fuse as close as possible to the power source, so close to the positive bus bar. You can look up what a 12AWG wire will handle at the length you're going to get an idea of the fusing. If it's less than the amps your air compressor is drawing then the wire is insufficient.

[uncle_bob]

Hi

Ok so what's and why?

They use these breakers in cars trucks and RV's. Used correctly, they are safe. They protect the wire from overload, that's what fuses and breakers are supposed to do. Since you just might bump into a distribution wire (thus tripping the protection) an auto reset setup makes sense. There's only just so much room in a trailer. Some stuff *has* to get buried.

The breakers are different capacities (amps). If you put a wire that should be on a 50 A breaker over on a 30A, it's still protected just fine. Your load may trip the breaker, but there is no fire risk. Get it the other way around (30 A wire on a 50A) and you have created a fire risk. You very much need to keep things matched up.

Ok, so what *could* you do if you have lots of time on your hands?

If you want to go "full bore" with the safety side of things, there are various outfits that have ideas. They don't write them for RV's but you can still follow them. One is to put a fuse on the end of any wire that connects to a power source. If you have a run from a battery to a charger, both ends get a fuse. Have a wire between two batteries? both ends get a fuse (ok, that one is nonsense on a 6" wire ...). Have a solar converter? It gets a couple of fuses. Have multiple solar panels? maybe they each get a fuse.

Still not happy you have spent enough on fuses? Ok. how about fusing all the returns?

Money left in the bank? Put in disconnect switches on all those lines.

Don't forget to label everything and put it all out where you can easily see it.

Something goes wrong. You need to see what. Ok, how about indicator lights on all those circuits and sections of circuits.

Money still in the bank?

All we have done so far is protect wire. We still haven't put in over voltage protection on all those circuits to protect the loads. Then there's under voltage disconnects ....

Is this all nuts? Sure it is. Once we switched to "time on your hands" things headed into crazy land. There is *always* more you can do. I think there's enough here to demonstrate that. This list could go on for a very very long while .....

Bob

[MSL]

Originally Posted by JeffKim

I forgot, with our dearly departed 2021 16' Bambi everything was a jumble without any box. Maybe a little better than what you have.

I'll take a swing at these:

1. Yes, breakers work in both directions.
2. You're asking why the brakes have a breaker? I'd guess that if the brakes short out or something it doesn't burn up the wire going to them or something?
3. I put a fuse on the XS output to the positive bus bar. My system is different since there's a Lynx installed which acts as a fuse box. So it's wired to the Lynx which goes to the bus bar.
4. Yes, I'd fuse it. The fuse protects the wire, so the rule of thumb is to put the fuse as close as possible to the power source, so close to the positive bus bar. You can look up what a 12AWG wire will handle at the length you're going to get an idea of the fusing. If it's less than the amps your air compressor is drawing then the wire is insufficient.

Thanks for the reply, Jeff.

No, I understand why you'd want the brake/break-away connection protected. I was asking why the +12-volt connection from the 7-pin connector used to charge trailer batteries was connected thru a breaker. But it doesn't really matter, I guess.

Yes, I have my XS fused prior to the connection to the copper bar.

I checked my compressor (Viair 88P) and max draw is 23 watts, so for the 8 ft or so the 12-gauge looks good.

Thanks again, Mark

[MSL]

Originally Posted by uncle_bob

Hi

Ok so what's and why?

They use these breakers in cars trucks and RV's. Used correctly, they are safe. They protect the wire from overload, that's what fuses and breakers are supposed to do. Since you just might bump into a distribution wire (thus tripping the protection) an auto reset setup makes sense. There's only just so much room in a trailer. Some stuff *has* to get buried.

The breakers are different capacities (amps). If you put a wire that should be on a 50 A breaker over on a 30A, it's still protected just fine. Your load may trip the breaker, but there is no fire risk. Get it the other way around (30 A wire on a 50A) and you have created a fire risk. You very much need to keep things matched up.

Ok, so what *could* you do if you have lots of time on your hands?

If you want to go "full bore" with the safety side of things, there are various outfits that have ideas. They don't write them for RV's but you can still follow them. One is to put a fuse on the end of any wire that connects to a power source. If you have a run from a battery to a charger, both ends get a fuse. Have a wire between two batteries? both ends get a fuse (ok, that one is nonsense on a 6" wire ...). Have a solar converter? It gets a couple of fuses. Have multiple solar panels? maybe they each get a fuse.

Still not happy you have spent enough on fuses? Ok. how about fusing all the returns?

Money left in the bank? Put in disconnect switches on all those lines.

Don't forget to label everything and put it all out where you can easily see it.

Something goes wrong. You need to see what. Ok, how about indicator lights on all those circuits and sections of circuits.

Money still in the bank?

All we have done so far is protect wire. We still haven't put in over voltage protection on all those circuits to protect the loads. Then there's under voltage disconnects ....

Is this all nuts? Sure it is. Once we switched to "time on your hands" things headed into crazy land. There is *always* more you can do. I think there's enough here to demonstrate that. This list could go on for a very very long while .....

Bob

Yes, free time can be a blessing or a curse ... I guess. I think I have a much better understanding of the positive busbar now. Now that things are installed and working, my last step will be this summer when I clean up the wiring mess Airstream left me with and create a diagram.

Thanks again, Mark