Starting my wiring project

[MontanaChinook]

Ok, after a slightly frustrated email back to them, they responded, and I've got the ground-neutral issue figured out. Makes perfect sense of course, now that I know. Everything seems right side up, except the words molded into the plastic..."neu on top", "gnd on bot".

Apparently some people install this thing upside down, on purpose. So if you flip it over, ground and neutral correspond correctly to how the electrician wired them. The ground bar is the one set farther back, with the large solid copper wire in it. Why they do it this way, I have no idea....everything is oriented one way, EXCEPT the ground and neutral hints molded into the plastic.

Either way, I bought myself a bus bar for my negative wires, so that they each have a separate connection, and I can personally run a thick wire to a clean spot on the frame from there.

Hopefully now you'll just be seeing progress instead of answering questions. Thanks!

[MontanaChinook]

One more question, just to be sure the AC side is all correct. If you look at the 6th post in this thread, you'll see photos I posted of the converter and diagram.

On the far right, in the side of the case, is "120V Hot". Four screws. When the unit showed up, the black AC wire was in there. But now I think it's going into the 30 breaker. That IS how the wiring diagram shows it. I just want to make sure, since when it came in the mail, there was a wire there, and why is it there if its not going to be used?

[Maineah]

One more question, just to be sure the AC side is all correct. If you look at the 6th post in this thread, you'll see photos I posted of the converter and diagram.

On the far right, in the side of the case, is "120V Hot". Four screws. When the unit showed up, the black AC wire was in there. But now I think it's going into the 30 breaker. That IS how the wiring diagram shows it. I just want to make sure, since when it came in the mail, there was a wire there, and why is it there if its not going to be used?

OK I think I understand what you are trying to say. If there was no main breaker the black wire would have been wired direct to the lug for the buss bar. What the guy has done is removed the black lead from the lug and attached it to a main breaker that is a good thing. What he is doing is back feeding the panel, breakers will work both ways so what he has done is attached the black feed wire from your power cord to the breaker this allows you to turn it off and kill power to every thing other wise you would have to turn off all the breakers to do so or unplug the MH it basically is a nice touch it does not have to be done that way but it's a better install it also protects the power cord from too much load if you were to add another breaker as it stands now with 2 15 amp breakers you can't over load it but if you had a 15 and a 20 or added another 15 you could with out the main breaker because the cord is rated 30 amps would that ever happen doubtful but possible.. Just another step to protect you from the camp ground wiring.

[Maineah]

Ok, after a slightly frustrated email back to them, they responded, and I've got the ground-neutral issue figured out. Makes perfect sense of course, now that I know. Everything seems right side up, except the words molded into the plastic..."neu on top", "gnd on bot".

Apparently some people install this thing upside down, on purpose. So if you flip it over, ground and neutral correspond correctly to how the electrician wired them. The ground bar is the one set farther back, with the large solid copper wire in it. Why they do it this way, I have no idea....everything is oriented one way, EXCEPT the ground and neutral hints molded into the plastic.

Either way, I bought myself a bus bar for my negative wires, so that they each have a separate connection, and I can personally run a thick wire to a clean spot on the frame from there.

Hopefully now you'll just be seeing progress instead of answering questions. Thanks!

Again you can land it under the same lug that the 120 volt ground is landed on but do it at the frame or make your own just be sure it's a good one it will save you a lot of head aches.

[Maineah]

Ok, after a slightly frustrated email back to them, they responded, and I've got the ground-neutral issue figured out. Makes perfect sense of course, now that I know. Everything seems right side up, except the words molded into the plastic..."neu on top", "gnd on bot".

Apparently some people install this thing upside down, on purpose. So if you flip it over, ground and neutral correspond correctly to how the electrician wired them. The ground bar is the one set farther back, with the large solid copper wire in it. Why they do it this way, I have no idea....everything is oriented one way, EXCEPT the ground and neutral hints molded into the plastic.

Either way, I bought myself a bus bar for my negative wires, so that they each have a separate connection, and I can personally run a thick wire to a clean spot on the frame from there.

Hopefully now you'll just be seeing progress instead of answering questions. Thanks!

OK I think why they did it that way is because both buss bars are set in plastic (insulated) so you could use either one because the neutral buss would be isolated so the bars could be either a neutral or a ground buss for ease of wiring.

[MontanaChinook]

Who knows...

As long as the guy wired the AC correctly, and I can go about wiring the DC, I'm happy!

Thanks

[Vanman]

What I did on mine was after install of the PD converter and ckt board and wiring, but before installing battery wires I turned off the AC main, put in only the first fuse, and turned every 12VDC device in the RV on. Next I turned the main AC breaker on and made a list of everything that was on. Turned off breaker, put fuse in next slot, on breaker, next list. Repeat till finished. Reason to do it this way is to make sure someone has not "fixed" some wiring by connecting two "hot" wires together that are on different fused lines. Maybe overkill, but with something this old, who knows. Easy to do and better safe than sorry and now you know what device is on each fuse.

[MontanaChinook]

Thanks!

On this rv, there is the fridge, one AC outlet, and the main breaker. Nothing else. I checked it out yesterday and saw all the wires the guy ran for AC. I'm running new wires for everything DC, so I'll know what's going on with everything, luckily.

I am glad that I decided to rewire it, instead of just hooking things back up. It's been frustrating, not knowing anything about wiring and converters, but its been a good learning experience...

Even though I still don't understand it too well, I feel like ive asked enough questions and i understand enough to be confident that I'm not doing anything wrong; nothing will be dangerous. Even though I could probably do some cool, thoughtful, custom stuff if I understood things better, it's good enough for now that I'm not doing a hack job, or setting up something that's going to fail or be dangerous.

[MontanaChinook]

Is it ok to splice negative wires for different fixtures together, or do I need to run a separate negative wire for every appliance/fixture? That's going to be a lot of wire, and a lot of places to attach all that wire to..

[MontanaChinook]

Think I found the answer...I looked back at a conversation and see that I was given the advice to not connect negative wires from multiple circuits into one. But it's fine to connect all negative wires on one circuit together.

[5Toyota]

that would make sense to me

[MontanaChinook]

Great, thanks. That saves some wire, and space on my negative bus bar!

[Maineah]

Think I found the answer...I looked back at a conversation and see that I was given the advice to not connect negative wires from multiple circuits into one. But it's fine to connect all negative wires on one circuit together.

Each circuit you power should have it's own ground wire. You can tie all the lighting for instance together on any of your 15 amp circuits but it needs to return to a grounding point not go all over the MH then return. Each circuit needs it's own ground to match the 15 amp load. You can then tie them to the same ground point as a frame ground that's fine that's even better because it would be a single point ground. If you go to an electrical supply house you can buy grounding buss bars that have several small ground points and one big one or more, join the big one to a frame ground with a hefty wire (#6 or 8 would be fine) like where your battery ground is and attach the smaller wires to the other terminals. You did confuse me a bit. A bit of caution do not attach a ground buss to any thing that might burn a poor ground connection can get just as hot as a power wire so no wood work.

[MontanaChinook]

Great, thanks. I did buy a bus bar. It will be wired to the frame, and all my negative wires are going to terminals on it. I haven't wired it to the frame yet, but I'm planning on using #10 wire, and getting a good spot on the frame by doing some sanding.

Think #10 is good enough? All I have are 4 lights with LED bulbs, a tiny, tiny water pump, and the furnace fan. Furnace calls for a fuse of no more than 7.5 amps or something, so it's a low draw. I'll eventually hook up one, at most two small fans.

[zero]

Think I found the answer...I looked back at a conversation and see that I was given the advice to not connect negative wires from multiple circuits into one. But it's fine to connect all negative wires on one circuit together.

There is no problem doing it either way. But if you join all into one - the one has to be big enough to carry all the current. It you had four circuits . . . e.g. a 30 amp, a 20 amp, and two 15 amps - you'd have a total of 80 amps. If you joined all the negatives together and connected to one wire - it would need to be big enough to carry 80 amps. That would require 6 gauge copper for a 10 foot run, #4 copper if 20 feet, etc. 20 feet at 40 amps would require #8 copper and #10 copper for 10 feet.

[Maineah]

The 120 volt ground is for protection not load carrying. The supply wire for the MH is #10 rated 30 amps that is why the main breaker is 30 amp. That's a done deal by a licensed electrician all ready. What you need to do is figure your 12 volt demands and add them all up and figure the total current draw. Your lights, pump, fridge and heater then chose a ground wire that will handle the entire load of all the circuits for your ground. WalMart sells battery cables with ring ends on them pretty cheap one of them would be more then enough to handle any 12 volt loads you can throw at it just cut one end off and land it on the buss bar and on the frame ground with a nice bolt. Two 4 light runs 200 watts if you are using a 12 volt fridge heater 175 watts water pump 85 watts heater about the same so with every thing running all at once you could draw 45 amps (worst case) at that rate a #6 wire would be in order.as your frame ground a # 10 is pushing the limits. The bigger the better that way you'll never over run the wiring if you add some more stuff.

[MontanaChinook]

True.

Ok. I'll go with bigger wire for the negative bus bar.

The fridge...I'll have to look at its wiring. It's already wired for the 120V, but I haven't noticed the 12V wires. Didn't really even think about it until now...I'll check it out!

[MontanaChinook]

I did a lot of work, then put this off while I worked on cabinets and other stuff. Time to wrap it up.

So, I'm going to put a fuse/switch outside the converter. External cut-off switch or whatever you'd call it. How do I determine what kind of switch and what amp? A breaker like is in the AC side of my power center? Like a breaker in a house? Or what?

And, I keep hearing to put a fuse near the coach battery. Same thing with that, how to determine the amps, and, do I put it before or after the battery isolator? Between the isolator and the battery, or just after the isolator, along the wire going from it to the power center?

There's no reason it shouldn't, since I think I'm doing all this correctly...but I'll still be somewhat amazed and have to have some kind of celebration if I hook this thing up and everything works!!

[Maineah]

Why? The 12 volt stuff is fused at the converter that's what the two 30 amps are. If you are going to put any thing between the battery and inside I would use a 35-45 amp auto reset breaker.I would also put one at the isolator up front also if there is not one there all ready.

[MontanaChinook]

I guess I heard that a power cut off switch, to quickly kill power to the converter, is a good idea. I don't know! Just going on what I heard. I don't see any fuses in the engine compartment, so unless they used a fusible link, I don't think there's anything up by the isolator and battery (my battery is in the engine compartment).

[Maineah]

I guess I heard that a power cut off switch, to quickly kill power to the converter, is a good idea. I don't know! Just going on what I heard. I don't see any fuses in the engine compartment, so unless they used a fusible link, I don't think there's anything up by the isolator and battery (my battery is in the engine compartment).

If anything goes wrong with the converter it will take out the converter fuses (30 amp). Now this still leaves you with a short length of wire between it and the battery can something happen? It is not impossible but pretty unlikely. Anything beyond the converter is protected by the fuses in the panel so that's ok. The bottom line to be perfectly safe right at the battery lead you can install a protection device but not a switch because it would do you no good if you are not there. The size of the battery lead wire dictates the fuse/breaker size a #8 wire would be 30 amps a #6 40. When I rebuilt the wiring system in mine I used manual reset breakers instead of the auto reset (the little cubes) my reasoning was if something tripped a 30 amp breaker I want to know why the auto ones just go back on and repeat the cycle until they fail as long as the fault remains. That’s no problem as long as you are there because you'll know right away when the lights go out but if you return and have no lights then would be the time to find out why. Now I’ll give you one more scenario to think about, the battery lead going to the isolator up front is not protected it is hot all the time from the coach to the isolator up front. There is a breaker up front that protects it going the other way but not in the back so if anything happened to the big #8 wire it going to get hot. Two breakers at the rear battery? I did the main reason was because I had a combiner in the rear that allowed me to charge the truck battery with my converter/charger. Is this overkill yes probably but one only has to have a look at the pictures of the motor home burning that was recently posted then decide.

[MontanaChinook]

Thank you.

Remember...my battery is in the engine compartment. So there's 8-10 feet of wire between the converter and the battery.

[MontanaChinook]

And for a breaker close to the battery, is this basically what I'm looking for? http://www.rvpartscountry.com/30AmpSingle.html

[Maineah]

It's pretty much standard for deep cycle batteries often they have both wing nuts and standard posts. As far as connections what ever works best for you. The breakers I was talking about are some thing like this they a manual reset many outfits carry them I like marine stuff it's often better built-http://www.iboats.com/Blue-Sea-Push-Button-Reset-Only-Thermal-DC-Circuit-Breakers/dm/cart_id.197741032--session_id.871875714--view_id.796959 There is no reason you could not use auto reset breakers right from the auto parts store I just like to find out why the breaker tripped that's just me and I don't like the ideal that it will keep resetting while I'm not there.

[MontanaChinook]

That works! Way cheaper than some of the things I've seen. Everywhere I go has the same kind of breakers. Those are different. Thanks!

I went to an rv place for the first time yesterday and saw their batteries, so yeah, I saw that they have both kinds of connectors.

[MontanaChinook]

Are there special terminals for the battery connection? The best site I can find with connectors specifically for battery terminals only went as small as 4 gauge wire connectors. I can find 8 gauge wire connectors, but they aren't specifically for battery terminals.

Not sure it matters, but I want to do it right!

[Maineah]

NAPA will have heavy duty terminals for your wire that will fit the threaded posts. They are solid copper no little plastic isolators and big enough to fit over the posts.. You are right the battery clamps were not made for smaller wire that is why they used tread post on the deep cycles. Often the posts are different size - 5/16 and the +3/8 so if you buy terminals you can size them to avoid reverse polarity.

[MontanaChinook]

Alright, thanks.

Next question!

I'm more or less using how this thing is wired to guide how I re-wire it. Just figure new wire is a good idea. But I don't understand what's happening here. The negative off the battery seems to go it's own way and I don't even see a reason to replace that wire.

But there are two red wires coming off the positive battery terminal, and they have me a little stumped. There's also splicing into different color wires, so it's even more confusing.

The wire on the right side of the picture connects up to the top post. The wire on the left goes towards the converter. Those are the wires coming off the + battery terminal.

I need to know how to wire this correctly. And remember...I get lost easily.

There is a green wire and red wire that go into the power center/converter. So that's my + and - . But what's happening here under the hood? What's what?

Seems like one wire goes straight from the battery to the converter. The other goes into the isolator. Then...what? One wire comes out of the isolator and goes to the converter, and one to the alternator? What about the green wire I see at the converter? Does that just get grounded to the frame, and not travel all the way back to the battery?

I'm not going to replace all this wire, but I'm replacing what comes off the + battery terminal, and what runs from the isolator to the converter. And I'll replace any bad connections.

[Maineah]

OK you got a mess there that is the remains of an old isolator. Here is what I think you have, one wire goes to the rear battery, one to the alternator and probably one to the front battery. In your case I think I remember you saying both batteries are up front. Bottom line you have no isolator the way it is wired. I would suggest disconnecting the wires and find out what goes to what by checking the voltage at each wire as you remove the battery terminals from each battery I don't remember what year your MH is if your alternator has an external regulator it does not need an exciter wire to the alternator and a 3 terminal isolator will work. I would say because they did some creative wiring the isolator is toes up. Once you find out where the wires go here is how it should be wired, the "A" terminal on the isolator will be from the alternator the other two usually are 1 and 2 it does not make a difference where they hook up either battery will work usually #1 is the front battery and #2 the rear. Most likely because your truck battery does not go dead the alternator and the truck battery wires are landed under the same terminal and the rear battery is landed by it's self. This does make it a crude isolator but the rear battery will never charge properly. With a solid state isolator the alternator requires some rewiring hence the splices.

[MontanaChinook]

Ok, thank you. It's a 1978.

I've been mostly happy with what I've found with this vehicle...people have definitely rigged some stuff through the years, but they've done a good job in their rigging, not a total hack job.

So I should probably be looking for a new isolator? Or you just mean that with how it's currently wired, my isolator isn't isolating anything?

And yes, both batteries are up front under the hood.

[Sunrading Arkansas]

Mine was set-up the same way - 1 house batt. upfront, one starting, and a 3-prong solid state isolator. In my case: the lower prong went to the starting batt., the middle prong went to the alternator, and the upper went to the house batt. There was a seperate, self-resetting circuit breaker between the isolator and the house batt. (50amp) and between the house batt. and the converter (30amp) - looks like yours had a fuse (left of the isolator in the pic) that served a similar function at some point.

I rewired my house batt. to the rear now, so it doesn't have such a long run from the house batt. to the converter.

[MontanaChinook]

Cool, thanks. That gives me an idea of how it should be. As long as I can trace which wire is which, it shouldn't be too hard to set it up right.

It would be good to move the battery back...and do a solar setup...and all sorts of other things.

But I'm getting to the point where I just want this thing back together and functioning! I'm doing my best not to get sloppy, but a lot of the ideas I've had are on the back burner, and I'm more just putting it back together the way it came apart (except with new parts), just to get it functioning. It's June now! Time to be actually using this thing.

[Sunrading Arkansas]

Yeah, I hear ya. It was a good, functional, set-up on mine when I bought it and it worked fine. The main reasons I changed it were 1) so I could use a bigger house batt (size 29) adn 2) so I could more easily install an inverter close enough to power a microwave. If I didn't need the microwave, I probably would have left it as-is. Best of luck getting your rig up and functional ASAP.

[MontanaChinook]

Well I don't have access to the photos right now, but this mess of a thread is coming to a close.

I got a cupboard up on Tuesday, which meant I could finally hook up a light. The wiring project has basically been on hold until I got the cabinets/cupboards that held the light fixtures installed.

So I have a fan and a light hooked up. Made sure my ground was good, connected the breakers between the battery and converter, fused the circuit, and we have power! And it didn't burn down overnight...

It seems that the LED bulbs have minimal draw. Right now there is a fan and one light on a circuit, but there will soon be one more light. Both LED. For the fan, it's a fantastic breeze 12V. I cut the cigarette lighter connection off and hard-wired it. That plug said "no greater than 4 amp fuse".

So...since its on a circuit with two low-draw LEDs, would a 5 amp fuse be good? Or should I actually go lower than 5?

This is my next point of confusion, since if I don't know if I should look at amps cumulatively, or individually.

So if I have three appliances on a circuit, one with a 5 amp draw, one with 8 amps, and one with 1 amp...how do I fuse it? 5+8+1=14 amp fuse, or fuse for the lowest amp appliance, ie 1 amp?

You probably won't recall, so I'll remind you, that I way overdid it on wire size. So I've got circuits with two LED lights running on 12 gauge wire. So I'm picking my fuses based on the appliances, not the wire...

[zero]

This is my next point of confusion, since if I don't know if I should look at amps cumulatively, or individually.

So if I have three appliances on a circuit, one with a 5 amp draw, one with 8 amps, and one with 1 amp...how do I fuse it? 5+8+1=14 amp fuse, or fuse for the lowest amp appliance, ie 1 amp?

You probably won't recall, so I'll remind you, that I way overdid it on wire size. So I've got circuits with two LED lights running on 12 gauge wire. So I'm picking my fuses based on the appliances, not the wire...

Circuit protection fuses are installed for one reason and it has little to do with your collective amp draw. The fuse (or breaker) is there to protect the wire from melting and starting a fire. Fuse size goes my wire size so the fuse blows before the wire melts. Every AWG wire size has a max fuse size allowed. Usually 30 amps for 10 gauge, 20 amps for 12 gauge, and 15 amps for 14 gauge and 7.5 amps for 16 gauge. I've got #2 battery cable connecting my isolator to my RV battery in the rear and that has a 200 amp fuse.

You can also use fusible-link wire that is a wire with special insulation designed to melt inside but not start a fire.

The proper way to wire a circuit with three items that can,all together draw 15 amps - is to have a 20 amp fuse and 12 gauge wire if no longer then 6 feet. #10 (with a 25 amp fuse) if the run is 10 feet.. #8 if the run is 15 feet. 12 volt wiring is problematic since volage is so low. It has a lot of loss. For example, a 20 amp load @ 12 volts with a 20 feet long wire has a voltage drop of 2.7% which is about as much loss as ought to be allowed.

The key to wiring with 12 volts is to keep all circuits as short as possible. Also, if let's say you've got a 30 amp circuit with 10 gauge wire and a small appliance hooked to it that only draws 5 amps - it can have it's own smaller fuse AT the appliance if wanted.

This is why few solar electric systems are rarely wired for 12 volts anymore (on houses). Some now are as high as 400 volts DC so the wire sizes can be smaller.