I have a small issue with my electrical system as you can see in the pic it has been "fixed" a few times. This unit both controls 110 and 12v. There is a relay that has a tierwrap holding it on, and I don't have lights in some areas, but all fuses have continuity.
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I would like to replace this thing, what do you recommend, one of the breakers shuts off all my 12v.
In my airstream I was going to go with one of these because I have glass fuses as well, but I did not do it yet.
http://www.amazon.com/Blue-Sea-Systems-Blade-Block/dp/B000THQ0CQ/ref=sr_1_2?ie=UTF8&qid=1412904921&sr=8-2&keywords=12+volt+fuse+panel (http://www.amazon.com/Blue-Sea-Systems-Blade-Block/dp/B000THQ0CQ/ref=sr_1_2?ie=UTF8&qid=1412904921&sr=8-2&keywords=12+volt+fuse+panel)
If it was my bus I would also change the breaker panel so that you had 2 separate boxes, but that is just me.
my first thought is that the coil in the relay must be bad...hence the "holdindevice"...
my next thought would be why would someone use a 110v coiled relay to begin with.
were i you, after deciphering why... eliminate the relay with appropriate manual switching.
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First of all, your 12v and 120v should NOT be even close to each other. Use proper panels and fuses for both. For the 120v stuff you are going to want a house type panel with real breakers. For the 12v stuff there are panels with breakers for RVs and boats that will work. Main breaker on both and breakers for each circuit. Please, please, please get them in totally separate boxes. One mistake can cause a world of hurt when mixing the two. Don't use your chassis ground for your 120v system, there is a huge difference between negative on the battery and 120v ground and the two should never meet. Kind of like your wife and your girlfriend, very, very bad things can happen if they meet.
So get proper AC and DC panels and make sure it is very clear which is which and which wires are AC and which are DC.
although it is not current code...it does look as original vs. backyard engineering...
the scariest thing i see is the bailing wire.
if the AC breaker contacts are fatigued, well that's scary enough to warrant a redo with current electrical updating.
heat arcing by poor contact in an AC panel would not prove beneficial to sound sleeping....
I recommend you locate someone that has a clue to redo all that mess.
That is scary.
Things like that and worse are parked next to us and are plugged in at rv parks.
Separating the two is not difficult.
12V house power should come from the batteries with correctly sized wires (not spliced) to a control bus.
There should be a fuse for each load that is connected to this bus. One load, one wire one fuse. Then wire up the next load.
AC power should come from shore power to a switch box. (You have a switch in your photo) From a generator to the switch box (different switch) or from the inverter to the switch box (third switch). The switch box should automatically default to the correct source. (Mine is if I am using inverter only and I plug into shore the shore switch picks up the load and the inverter switch drops it. If I then start the generator, the generator automatically picks up the load and the shore power drops it.)
Whatever the selected source is will then be connected to the breaker panel. Proper sized breakers and wires then would power circuits.
Please get someone to help you clean that up.
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi643.photobucket.com%2Falbums%2Fuu152%2Fakroyaleagle%2FBusElectricalSystem001.jpg&hash=a67ee0f3bb4082aa466d89db5874570a8124d85e)]
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi643.photobucket.com%2Falbums%2Fuu152%2Fakroyaleagle%2FBusElectricalSystem002.jpg&hash=a5589fe02b134390e51b2da14531d7101d1b1ad3)][URL=http://s643.photobucket.com/user/akroyaleagle/media/BusElectricalSystem002.jpg.html] (http://s643.photobucket.com/user/akroyaleagle/media/BusElectricalSystem001.jpg.html)
My first reaction was that is an AC distribution box with a built in transfer switch. The upper is obviously the breaker section, the lower looks like a transfer switch and controller, not sure what all the little fuses are for, might be the 12v. I'm with everyone else - take it out, trace it out, replace with modern home or RV distribution panels for AC and DC, and get a new ATS.
Brian
Quote from: Oonrahnjay on October 09, 2014, 07:06:16 PM
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That's a fine mess. Bet it took awhile to get to look that way. ::)
Merle.
Quote from: ol713 on October 10, 2014, 08:27:21 AM
That's a fine mess. Bet it took awhile to get to look that way. ::) Merle.
I'm just surprised it works at all without killing someone. Just a reminder of how bad wiring/electrics can be ...
Thanks everyone, and yes I plan on replacing this mess. We do not camp anywhere near shore power, so the 12v stuff will all go and be connected to the battery bank (the PO did no boondocking, so in this box was the 120v power, a transformer to bring it down to 12V dc and a small 12v distribution panel (the fuses)) 120V will only be supplied by the generator, and that will give us power for the AC and central vac. and instead of running a 12v power supply off 120v, when the generator is running it will power a battery charger to supplement and improve the house batteries. An inverter will be put in place as the "normal" 120 power source for the microwave and coffee maker.
Quote from: mung on October 09, 2014, 07:20:29 PM
First of all, your 12v and 120v should NOT be even close to each other. Use proper panels and fuses for both. For the 120v stuff you are going to want a house type panel with real breakers. For the 12v stuff there are panels with breakers for RVs and boats that will work. Main breaker on both and breakers for each circuit. Please, please, please get them in totally separate boxes. One mistake can cause a world of hurt when mixing the two. Don't use your chassis ground for your 120v system, there is a huge difference between negative on the battery and 120v ground and the two should never meet. Kind of like your wife and your girlfriend, very, very bad things can happen if they meet.
So get proper AC and DC panels and make sure it is very clear which is which and which wires are AC and which are DC.
Just to clarify, are you saying that the green/ground wire of a three wire 120 volt system should be prevented from contacting any metal part of the RV? This would require the use of plastic boxes for switches, outlets etc since the ground wire is often hooked to the metal frame of an outlet and thus also to the metal of the box. If the metal boxes are used they are likely to come into some contact with the metal parts of the RV.
Just a small point. It's perfectly OK to have 120VAC and 12VDC in the same "box" as long as they are in separate compartments within the box. that is how almost all RV units are configured. I have such a unit in the bus, handles some of the house AC distribution and the DC distribution in separated compartments, and same in my camper. This unit as pictured appears to have the AC in the top compartment and the DC in the bottom so it was probably legal and to code when it was first installed.
Brian
It is ok to, in fact necessary to ground both the DC and AC power to ground, as in the bus steel frame
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Yes Thor, you don't want to use the bus chassis to ground the 120v side, you want it isolated. In true operation a vehicle chassis is never "grounded" it is really negative on a DC circuit (unless you haven't converted from positive "ground" yet). In 120v house wiring ground is literally a ground rod driven into the ground.
"It is ok to, in fact necessary to ground both the DC and AC power to ground, as in the bus steel frame"
Not even close to OK, against code, and potentially very, very dangerous. All 120v grounds should be taken back to the shore power ground not through the chassis.
I guess I won't tell the electrician that did ours and countless others that
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...and THIS , gentlemen, is how accidents happen. ::)
Not sure where is conversation is going; all of my 120/240 vac equipment is grounded to the bus chassis. The ac neutral is bonded to the ground at the power source. This bond should be at the power pole when the bus is plugged in to shore power, at the generator when on generator power or at the inverter when on inverter power and only one bond should be in place at a time. Do not confuse ac neutral and safety ground.
Quote from: mung on October 10, 2014, 11:18:19 AM
"It is ok to, in fact necessary to ground both the DC and AC power to ground, as in the bus steel frame"
Not even close to OK, against code, and potentially very, very dangerous. All 120v grounds should be taken back to the shore power ground not through the chassis.
Completely wrong. The bus frame should be grounded to the incoming ground from the pole, it should be bonded to the ground in the fuse panel and it absolutely must be the DC ground, unless you don't want your engine to run. All of the bus DC wiring uses the chassis as ground. Now, what you should never do is use the bus chassis as the grounding conductor (grounding conductor is what you would normally see as a bare copper or green insulated wire in a cable) for any part of an AC circuit. You always use a grounding conductor in a cable for any AC power feed. I It's completely permissible and extremely common to use the chassis as the grounding conductor in a DC circuit, obviously.
Brian
This ground question is intriguing so I went and checked out my Winnibago(1973 Indain) that has a factory installed Onan generator. There is no continuity from the chassis to the ground wire of the shore power cord. The ground of teh generator though is connected to the chassis.
...
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Which will tie all grounds to the chassis
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So, if you pull up to a camp site and the pole isn't grounded like it should be, then the wife plugs something in that has a neutral fault, where is the current going to go folks? Also keep in mind that a bus is all metal vs most RVs which are not.
Quote from: mung on October 10, 2014, 01:54:56 PM
So, if you pull up to a camp site and the pole isn't grounded like it should be, then the wife plugs something in that has a neutral fault, where is the current going to go folks? Also keep in mind that a bus is all metal vs most RVs which are not.
it will run back to the source...if the coach is wired correctly and you previously checked the pedestal for proper wiring....open between neutral and ground.
in other words it will do the same thing it would do at your house.
http://www.rvtravel.com/?q=category/electrical (http://www.rvtravel.com/?q=category/electrical)
http://www.noshockzone.org/category/rv-safety/ (http://www.noshockzone.org/category/rv-safety/)
http://www.noshockzone.org/generator-ground-neutral-bonding/ (http://www.noshockzone.org/generator-ground-neutral-bonding/)
Great sources Don!
I saved them in my files. I learn a lot from things like that. Plus I can always go back and reference it. If I can find it in my files.
In August I was on a government site that by contract supplied power to my coach. Before They turned the power on they inspected the connections and did a ground test between my panels and frame, that was one of the tests. My coach passed, don't think they would have hooked up yours,,,,,just saying.
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If the 120v has the neutral bonded to the ground that is a very bad thing on a coach, it isn't supposed to be that way. If it isn't bonded, well what good does the ground actually do?
If you haven't read the No shock zone articles eagle 19952 references you need to---if only to stay alive!
Quote from: oltrunt on October 10, 2014, 06:53:34 PM
If you haven't read the No shock zone articles eagle 19952 references you need to---if only to stay alive!
If the 120v has the neutral bonded to the ground that is a very bad thing on a coach, it isn't supposed to be that way. If it isn't bonded, well what good does the ground actually do?
you say a bonded neutral to the ground (which it is not attached to the chassis) is a bad thing.
then you turn around and say in the following sentence "If it isn't bonded, well what good does the ground actually do."
please explain.
the neutral bond that you speak of, you need to put in words your definition....where does it show that they are connected. neutral does not attach in any fashion to the chassis.
So, if I'm not plugged into a shore line and my inverter is supplying 120v through my ac panel, to what should my ac ground from my panel be attached?
it is vitally important that the connection between the AC safety grounding wire and the neutral wire occur only at the power source. That means, at the onshore transformer supplying the dock shore cord, or at a generator or inverter—when and only when one of those is supplying power
Neutral and ground must be bonded together at one and only one point. That point must be solidly grounded to earth.
If the neutral and ground get together in your 50amp cord, you will let the smoke out of a lot of stuff!
So what I don't understand is, when I'm going down the road (or parked) using my inverter, what makes me "solidly grounded to earth"? (other than gravity ;)) Does the inverter bond neutral and ground when switched on?
http://ecmweb.com/bonding-amp-grounding/shocking-truth-about-grounding-electrode-conductors (http://ecmweb.com/bonding-amp-grounding/shocking-truth-about-grounding-electrode-conductors)
If you do use your chassis for an AC ground, I hope you carry a grounding rod and a sledge hammer with you.
Quote from: mung on October 11, 2014, 06:23:19 AMhttp://ecmweb.com/bonding-amp-grounding/shocking-truth-about-grounding-electrode-conductors (http://ecmweb.com/bonding-amp-grounding/shocking-truth-about-grounding-electrode-conductors)
Very interesting, Vern. I had always assumed what they say not to assume!
think about what you are saying....
Quote from: mung on October 11, 2014, 06:26:00 AM
If you do use your chassis for an AC ground, I hope you carry a grounding rod and a sledge hammer with you.
i think you are failing to remember that the earth ground is a fault ground which is a secondary path to the source..which could be a pole a generator a solar control a windmill or an inverter.
in the event of a fault ( and properly wired) the neutral is what trips the breaker... not the ground.
So. Tell me how that ground rod is going to help you out at sea....or in an air plane.
PS no grounding rod here, 12 years in... I do have a 8 pound sledge that i use to thump tires.
PSS I wsh I was better at penning concepts.
Quote from: akroyaleagle on October 10, 2014, 10:10:00 PM
If the neutral and ground get together in your 50amp cord, you will let the smoke out of a lot of stuff!
the cord is not the source.
The real issue is that if you have the chassis sharing a common ground with both 12v and 120v sources there is the potential that your 120v source can fry everything on your 12v side. Probably won't happen in most failure modes, but is still well within the possible outcomes of a failure.
Vern, if every thing is on a common ground, wired properly, the breaker trips, saving any voltages from smoking anything...whether AC or DC.
again where are you putting the ground rod on the boat or plane ?
Quote from: mung on October 11, 2014, 01:00:00 PM
The real issue is that if you have the chassis sharing a common ground with both 12v and 120v sources there is the potential that your 120v source can fry everything on your 12v side. Probably won't happen in most failure modes, but is still well within the possible outcomes of a failure.
Quote from: mung on October 11, 2014, 01:00:00 PM
The real issue is that if you have the chassis sharing a common ground with both 12v and 120v sources there is the potential that your 120v source can fry everything on your 12v side. Probably won't happen in most failure modes, but is still well within the possible outcomes of a failure.
I'm Mike Sokol from No~Shock~Zone which has a number of my bonding and hot-skin articles linked above. Not only am I a Master Electrician and EE, I also have the RVIA handbook in front of me. Every RV built in the USA is designed to have the incoming 120-volt EGC (Electrical Grounding Conductor or Safety Ground) bonded to its chassis, door frames, and all metal structures. And all 12-volt DC vehicle systems have their negative terminals bonded to the same vehicle chassis. Even though it seems like there should be some sort of dangerous interaction between the AC and DC systems, in fact there is no interaction at all. I'm also an expert on electrical failures, and there are no failure modes I can think of that would cause a RV's 120-volt system to "fry" the 12-volt system. So, if you know of one, please post a schematic and current flow diagram so I can evaluate it.
Also as noted, it IS vitally important that the ground and neutral wires inside your RV/Bus are isolated from each other. They will eventually be bonded together, but all the way back at the service panel at the incoming power line, or inside your on-board generator's transfer switch. I also came up with a simple G-N bonding plug for portable generators that fulfills the same function. This is not actually earth "grounding" but G-N "bonding" which fulfills the same function on a floating electrical system powered by an isolated generator such as a Honda EU2000i and similar.
And while its hard to believe, a ground rod will not really "ground" your RV since the earth itself is a pretty poor "ground". A "ground rod" can measure up to 100 ohms to the earth and still pass code. It's really there for lightning protection, not ground fault currents.
I think one of the reasons this is so confusing to most consumers and many technicians is that the word "grounding" and "bonding" are used interchangeably, when they are, in fact, very different things that fulfill very different functions. I've just published a book on RV Electrical Safety for Consumers, and now working on one for RV Technicians. It will include all sorts of additional electrical troubleshooting and wiring information.
Finally a voice of reason. And expertise. And qualifications from actual qualifying places. Saying, I am proud to note, much the same thing I said, but way better. ;D Nice to have you visit, Mike.
Brian
Mike, I don't have time right now do draw a schematic, but what would happen if the ground on the plugin at the campground isn't solid, then you have a fault from the hot side to a a device's ground? Would the 120v hot leg not try to find the path of least resistance? Is it not very possible that the current could back feed through the 12v ground wires?
Been in some high end newer campgrounds that the neutral and earth grounds were connected(not correct) at the pedestal. Why?? the person that did it was not educated. Best to ck yourself.. you should have no continuity between the 2. One tip in anything bus -metal bldg --I have a habit of first touch with back of fingers;if you complete ground your fingers will contract away from object. Not to be used to test earth ground! Just a old habit from the past when things were much worse. Just a little trivia. Bob
I too would like to thank Mike for chiming in, Thanks Mike !!
I emailed some questions to him last year and was grateful for a timely response.
Quote from: mung on October 11, 2014, 02:20:24 PM
Mike, I don't have time right now do draw a schematic, but what would happen if the ground on the plugin at the campground isn't solid, then you have a fault from the hot side to a a device's ground? Would the 120v hot leg not try to find the path of least resistance? Is it not very possible that the current could back feed through the 12v ground wires?
Quote from: robertglines1 on October 11, 2014, 02:37:50 PM
Been in some high end newer campgrounds that the neutral and earth grounds were connected(not correct) at the pedestal. Why?? the person that did it was not educated. Best to ck yourself.. you should have no continuity between the 2. One tip in anything bus -metal bldg --I have a habit of first touch with back of fingers;if you complete ground your fingers will contract away from object. Not to be used to test earth ground! Just a old habit from the past when things were much worse. Just a little trivia. Bob
Actually, you SHOULD read continuity between the Neutral and Ground at the pedestal. It should NOT be bonded internally at the pedestal. Rather, the Ground and Neutral are bonded together back at the service entrance panel. However, NEVER connect a meter in OHMS mode across any receptacle/plug contacts since the slightest voltage there will blow up the meter, or at least its internal fuse.
I just produced a video review of the Amprobe PK-110 test kit which details how to test 20, 30 and 50 amp outlets on a campground pedestal for correct voltage, H-N polarity, and Ground. This has not been officially released yet, but it has been vetted and approved by Amprobe's engineering group. See below:
http://www.youtube.com/watch?v=W5pLlZm8O84# (http://www.youtube.com/watch?v=W5pLlZm8O84#)
Mike Sokol
Quote from: robertglines1 on October 11, 2014, 02:37:50 PM
Been in some high end newer campgrounds that the neutral and earth grounds were connected(not correct) at the pedestal. Why?? the person that did it was not educated. Best to ck yourself.. you should have no continuity between the 2. One tip in anything bus -metal bldg --I have a habit of first touch with back of fingers;if you complete ground your fingers will contract away from object. Not to be used to test earth ground! Just a old habit from the past when things were much worse. Just a little trivia. Bob
I would think the pedestal is the source of neutral/ground bond for the bus, so you should absolutely have continuity between neutral and ground at the pedestal. The question would be would that bond be provided locally at the pedestal, or carried back to the main panel. The pedestal should be served with a three or four wire cable and the neutral-ground bond should be at the main panel, I would expect, although there is an argument for locally bonding. In Canada sub-panels in outbuildings are locally grounded and bonded to neutral in most cases. I test every connection to a pedestal with a test plug device, every one so far has offered me a bonded ground and neutral. Mind you I probably have stayed in less than a few dozen campgrounds.
Brian
Quote from: mung on October 11, 2014, 02:20:24 PM
Mike, I don't have time right now do draw a schematic, but what would happen if the ground on the plugin at the campground isn't solid, then you have a fault from the hot side to a a device's ground? Would the 120v hot leg not try to find the path of least resistance? Is it not very possible that the current could back feed through the 12v ground wires?
In that instance, the entire chassis/skin of the RV will be AC voltage biased above earth potential. But because EVERYTHING is at the same voltage, there's no current flow back into the DC systems. Seems counter-intuitive, but that's how it really works. But I don't say this from theoretical book diagrams. I build the tests and demonstrations myself and take readings so I understand how improperly wired systems misbehave and how you troubleshoot them. Here's a video of me opening the 120-volt ground on a 40-ft RV and biasing the entire thing with up to 120-volts AC. Nothing was damaged, but it is highly dangerous to anyone standing on the ground and touching anything metal on the RV. See below:
http://www.youtube.com/watch?v=Y8h64X33aKg# (http://www.youtube.com/watch?v=Y8h64X33aKg#)
Thanks Mike for valuable input, I admit I have little to no patience when it comes to explaining the obvious, I am thankful that there are people like you around that not only have the knowledge but the ability and desire to explain it to the masses.
I have read your articles before, as you know there are not many to be found concerning RV's. I tend to trust the professional convertors that have installed 100's if not thousands in their conversions without problems (well maybe I should retract the "without problems"), not all do it perfectly as know.
P.S. Did you have any input in the 2014 NFPA 70 (is it article 514? memory left me long ago) concerning the wiring of RV's.
Eagle, didn't mean to miss your question on the planes and boats. Well most planes don't have 120v except for new airliners that use inverters to get that. Now lets talk about boats. Hmm, so first of all, the water makes a very good ground and because of that, there is a huge issue with galvanic corrosion. But more to the point of 120v service to a boat, well since my boat is GRP (glassed reinforced plywood) how exactly would I tie my 12v or my 120v to the chassis? fiberglass and plywood doesn't make a very good conductor. So all of my 12v and 120v have home runs and the two never meet. So, why is this 100% common on boats and really the only way to connect your electric, but not common on buses and RVs? Kind of interesting isn't it?
Quote from: mung on October 11, 2014, 06:36:06 PM
Eagle, didn't mean to miss your question on the planes and boats. Well most planes don't have 120v except for new airliners that use inverters to get that. Now lets talk about boats. Hmm, so first of all, the water makes a very good ground and because of that, there is a huge issue with galvanic corrosion. But more to the point of 120v service to a boat, well since my boat is GRP (glassed reinforced plywood) how exactly would I tie my 12v or my 120v to the chassis? fiberglass and plywood doesn't make a very good conductor. So all of my 12v and 120v have home runs and the two never meet. So, why is this 100% common on boats and really the only way to connect your electric, but not common on buses and RVs? Kind of interesting isn't it?
First off GRP is "glass reinforced plastic". I'm not sure what "glassed reinforced plywood" might be unless you are referring to cold molded plywood.
Second, in the marine world, there is a heated debate about the connection of 12 volt grounds and the bonding system for electrolysis prevention but this forum is most definitely not the place to open that discussion. Boats float in water which is more or less conductive and that introduces a whole new level of electrical complications. What happens in the boating world has some relevance to what you can or should do on your bus but its not definitive.
i give up....
What if your at a dock with shore power in a steel boat that is big enough to land an airplane ?
PS.
Boeing B 737 NG
Primary electrical power is provided by two engine integrated drive generators (IDG's) Which are rated at 90Kva and supply three-phase 115 volt, 400 cycle Alternating Current
Quote from: mung on October 11, 2014, 06:36:06 PM
Eagle, didn't mean to miss your question on the planes and boats. Well most planes don't have 120v except for new airliners that use inverters to get that. Now lets talk about boats. Hmm, so first of all, the water makes a very good ground and because of that, there is a huge issue with galvanic corrosion. But more to the point of 120v service to a boat, well since my boat is GRP (glassed reinforced plywood) how exactly would I tie my 12v or my 120v to the chassis? fiberglass and plywood doesn't make a very good conductor. So all of my 12v and 120v have home runs and the two never meet. So, why is this 100% common on boats and really the only way to connect your electric, but not common on buses and RVs? Kind of interesting isn't it?
Bob back when my boat was built in England it was marine ply with fiberglass on both sides of it and they called it GRP. That term has now been changed to plastic, but fiberglass was so new back then that they way over engineered it.
I think what is important is that when you have metal in any vehicle, it must be grounded to the AC system. The 12v system uses the frames of metal vehicle mainly because it is cost effective, they do not have to run a wire back to the battery. If the vehicle/boat does not have a metal frame they would have to run the wires back to the battery to complete the circuit. Personally I do not like using the frame for the return, it usually is where you find a problem with a bad ground connections.
Quote from: mung on October 10, 2014, 01:54:56 PM
So, if you pull up to a camp site and the pole isn't grounded like it should be, then the wife plugs something in that has a neutral fault, where is the current going to go folks? Also keep in mind that a bus is all metal vs most RVs which are not.
My 26 ft Airstream is a whole lotta metal.... ;)
Trivia - the main reason that car makers went to negative ground electrical systems back in the late 1950's and early 1960's was to make the chassis wiring sacrificial, electrolytic corrosion-wise. Similarly the reason telephone plant wiring uses negative 48vdc for the battery voltage on the outside plant wiring to your home is to make the wiring the part that doesn't corrode electrolytically. When your phone goes off-hook an AC frequency is superimposed atop the -48, here it's 350hz and 440hz. When the phone rings, they impose a 90 volt AC 20hz on top of the -48 volts (so it swings from zero to negative 93 volts, which is enough to give you a good wake up shock, you can barely feel dial tone but I was knocked off a ladder when I was casually holding a tip and ring pair and someone called that number...)
So AC and DC coexist all over the place. Ontario Hydro used to run digital data signals on top of the high voltage 60hz distribution network.
Brian
Further (and then I really do give up), regarding boats in water....
In a properly wired system, current traveling aboard on the hot wire returns solely through the white wire. Because a boat floats in a conductive medium, interconnecting the green and white wires aboard affords current returning to its source—the transformer ashore in this case—through three paths: the white wire, the now-connected green wire, and the water via bonded underwater metal hardware such as the engine/propeller, strainers, and seacocks. Contrary to popular belief, electricity takes all paths back to its source, not just the path of least resistance. This presents a clear hazard to swimmers, and those aboard may also be at risk, depending upon the nature of the fault. Therefore, it is vitally important that the connection between the AC safety grounding wire and the neutral wire occur only at the power source. That means, at the onshore transformer supplying the dock shore cord, or at a generator or inverter—when and only when one of those is supplying power to the vessel.
http://www.proboat.com/demystifying-the-neutral-to-ground-connection.html (http://www.proboat.com/demystifying-the-neutral-to-ground-connection.html)
Yet code says not to run low voltage control wires with 120v or above circuits.
stay safe.
Quote from: mung on October 12, 2014, 08:16:00 AM
Yet code says not to run low voltage control wires with 120v or above circuits.
The code is concerned with insulation values. If you run your 12v with wiring that has an insulation rated at the same or greater than your 120v that will meet the NEC. This is for insulation of wiring in shared raceways. The distribution panels should be separate.
I reviewed my original post and response on continuity between green wire and white at campground post. You say yes.. Then in effect when you plug in you complete the the connection of green Safety and white common you so carefully kept separate in in bus. So ? keep separate in coach but defeat at pedestal? Also complete ground Chassis of bus DC to AC when you plug in. I will leave this discussion to those whom are expert.One advise to guys whom have to do their own.. Keep your color code standard so you know what wire does what. Rolls of wire are cheap when in the future you are someone trying to read your mind has to figure it out. Example 12 Volt DC= yellow DC grounds =Black 24Volt dc +=red. 120-240 volt ac Green =safety ground white = neutral/common red=line 1 black = line 2 . I use tatoo # on wires to identify circuits. So I'm totally wrong? I stay confused about the grounds because If they are bonded anywhere the whole system becomes one. Yes I do understand if one ground(say white) fails in a outlet the 2nd(suppose green safety) will complete circuit.
My response: I noticed original poster withdrew his picture and is probably dismayed. Please don't feel like that! Know you are not alone... This subject has been a discussion for years and many time on the board. If you want to have a idea of what you have plug it into a proper outlet and have someone test it for you. Respect to all. Bob
The reason you keep ground and neutral separate on the bus is that neutral is the return path for the load current. Current goes out to the load, and returns on the neutral conductor, all the way back to the bond between neutral and ground at the source. What that means is that no current is present on the grounding conductor, because it's not connected to neutral until the source panel. So no current can be present on the chassis of the bus (unless there is a fault, which would trip a GFCI device). If you connect ground to neutral anywhere other than the source the return path from the load is split, and in a reasonable installation the return current will be shared between the two paths. It's reasonable to presume that the cabling will be about the same, so roughly half of the return current will flow on the bus chassis. Normally, no one cares because all the current goes to ground eventually, but in many failure or fault situations you could get that "hot skin" situation where someone could be electrocuted.
There is a truism that electricity seeks the path of least resistance. That's true but people take it as an all or nothing statement, which is not true. Electricity will flow through all paths based on the ratio of the resistances of the paths. If you have a bond between neutral and the grounding conductor in a load path, for ever after the current will flow based on the ratio of the resistance to ground of the two paths. That's why it's so important to keep neutral (also called the grounded conductor) and "ground" - properly called the grounding conductor - separate until they are bonded at one place. The real thing that all this does is ensure that circuit breakers pop when there is a short circuit to "ground". And that all return path current flows in the proper conductor, not the chassis of the bus...
Edit; A better way to think of "ground" is as a zero voltage reference that you utilize to provide an effective ground-fault path to clear a fault. That's why a generator that sits in a bay in your bus has a "ground" that you bond to neutral so that you are safe in your bus when your generator is running.
Brian
Good job explaining Brian, are you a fellow electrician?
It is also important that when you transfer from generator to shore power that you break the neutral in your transfer switch, otherwise then you will have multiple paths situation.
I'm neither an electrician or electrical engineer by license or degree, but I spent 35 years in data communications. I designed equipment rooms, I designed networks, I did protocol analysis and network engineering. I was an electronics technician and did my stint on a bench doing chip level repair and analysis of 1980's computer and digital circuits. I was part of a very small company that built the first national Internet backbone network in Canada. That network is now owned by Verizon...(geeks, it was part of Alternet). I spent 30 of those 35 years in sales, so my key competency was explaining all this new-fangled crap to executives who really didn't want to know... At the end of the day I was an interpreter and teacher, I just got paid commission...
Brian
Quote from: robertglines1 on October 12, 2014, 11:38:24 AM
I reviewed my original post and response on continuity between green wire and white at campground post. You say yes.. Then in effect when you plug in you complete the the connection of green Safety and white common you so carefully kept separate in in bus. So ? keep separate in coach but defeat at pedestal?
Yes, that's correct. You have to maintain separation of the neutral and chassis ground on the bus/RV, and it get's bonded together when you plug it into the pedestal. However, the pedestal doesn't do the G-N bonding.... the main entrance service panel does it. The reason for this is that the "ground wire" which is technically called the EGC (or Equipment Grounding Conductor) is not allowed to carry any of the return currents. It's only supposed to carry ground fault currents (short circuit from your hot wire to the bus chassis) and that's supposed to trip the Circuit Breaker (technically called the OCPD / Over Current Protection Device). So you're technically not "grounding" your bus chassis to the shore power cord, you're "bonding" it to the entrance service panels connection where the Neutral, EGC Ground, and Earthing Ground Rod all connect (bond) together. That's also why a ground rod next to your bus doesn't actually "ground/bond" your vehicle. The ground rod likely has an impedance to the earth of around 100 ohms. That implies that a 120-volt short circuit to your bus chassis from something like a pinched wire will only produce about 1.2 amps fault current to the earthed ground rod next to your bus. But the EGC must have an impedance of less than 1 ohms all the way back to the service panel, so it will attempt to push at least 120 amps of current, which will certainly trip any 20, 30 or 50 amp breaker in the circuit.
Don't feel bad if you're confused about this. I'm the moderator on the AC Power & Grounding Forum at ProSoundWeb.com and the subject of grounding vs. bonding comes up all the time. Also, I find myself explaining this concept to electricians and inspectors more than I should have to. It's just not obvious how it all works, and the NEC book doesn't explain theory... it just tells you how to wire stuff.
One of the things I'm fishing for is a grant that would allow me to teach classes on this at campgrounds and RV dealerships around the country. I have a bunch of table-top and full-size demonstrations on how this all works. But I just can't afford to quit my day job and teach this full time, as much as I would like to.
Well I hope you are able to get your grant. You definitely are able to explain it well. I run across many people and have been many places where I have had to fix grounding and bonding issues. I cannot say I know every aspect of it but I try to research anything if I am not familiar with it. I have a fairly good knowledge of grounding and bonding because we do a lot of work for the telecom industry and they are fanatical about having grounds with less than 5 ohms. They typically have a ground system.
Three questions, because I'm curious:
1. Is it unsafe to have no 120v chassis ground?
2. Where should the 120v chassis ground be (main panel)?
3. Is it okay to have multiple 120v chassis grounds?
Thanks,
Mike
Quote from: Midwilshire on October 12, 2014, 06:59:25 PM
1. Is it unsafe to have no 120v chassis ground?
Yes, it is unsafe to have an "ungrounded" chassis that's isolated from the 120-volt EGC (Equipment Grounding Conductor). Plus it's both an NEC and RVIA code violation.
Quote
2. Where should the 120v chassis ground be (main panel)?
Yes, the RV's main panel is the approved bonding/grounding spot for the EGC
Quote
3. Is it okay to have multiple 120v chassis grounds?
Yes, a secondary chassis bonding/grounding point is allowed and probably desirable.
I traced every wire in the bus and have a few additional questions.
All my house 12v has both positive and ground runs back to the distribution panel.
There is no continuity between house 12v and Chassis 12v system, nor between 120v and chassis or house 12v.
Should I all interconnect them, and how?
I call that "home-run" wiring for the DC grounds. I pulled all of mine back to a bus bar, and tied that bus bar to chassis ground. I then tied my batteries to chassis ground. That lets the few 12v loads I have that are not home-run wired to work just fine (dash radio and fans). That also lets me bridge the house batteries with the start batteries for charging from the alternator and for starting assist. So yes, I would tie your house battery system and wiring to chassis ground.
The answer on bonding the house 120VAC system to ground is above, from Mike. Yes, the 120VAC system should have it's ground connected to the chassis.
Brian
I am glad I sparked( pun very much intended) this discussion. I have this as my plan, please correct as needed.
The only time we pony up to shore power is at home to cool the fridge down before taking off, we camp just on week-ends at race tracks.
In our Winnebago ( a classic 1973 Indian ) we got by with a single house battery and a 4000w generator for the coffee maker and Microwave( used the AC once last summer)
I would like to camp for longer periods( I am trying to convince my wife we should be full timers)
So the set up as I see it, 4 or 6 6v deep cycle batteries, a 2000w inverter( for microwave and coffee maker) and a generator for those times when AC is a real need.
To save money I will forgo an automatic transfer switch and just plug my shore power cord into the inverter, or generator, or shore power. When running the generator I will also run a charger to maximize efficiency, and while driving have a switch to allow the bus alternator to give a helping hand to the house batteries.
Eventually solar power will be added( when I convince the wife that full timing is a good idea) , what size wire should I take from roof to basement since I have the possibility of running them since it's almost gutted.
What's missing in my plan, what else should I plan for in the future, and what should I change. For those of you that did or re-did a conversion here is a pic of some of my wiring.
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi144.photobucket.com%2Falbums%2Fr179%2Frepare-brise%2Fbus%2FA0B730F6-F4F0-488D-869F-316AEB760EE5.jpg&hash=9f95ae9a05a14f973f1ec59bd770f39144729cd6)
What racing do you do?
Brian
We race vintage Dirt Modifieds (https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi144.photobucket.com%2Falbums%2Fr179%2Frepare-brise%2Fvintage%2Fvintage%252010%2Fb5844f57-1.jpg&hash=215fcd68853105d5fa02bb6bde5e4a2f0307b3ed)
This one is mine, the 2 others are my cousins cars.
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi144.photobucket.com%2Falbums%2Fr179%2Frepare-brise%2Fvintage%2Fvintage%252010%2FUntitled.jpg&hash=873f5a7c852169f5cb2a5ee92bd2237b9af84d14)
Quote from: yvan on October 13, 2014, 06:12:09 PM
I am glad I sparked( pun very much intended) this discussion. I have this as my plan, please correct as needed.
The only time we pony up to shore power is at home to cool the fridge down before taking off, we camp just on week-ends at race tracks.
In our Winnebago ( a classic 1973 Indian ) we got by with a single house battery and a 4000w generator for the coffee maker and Microwave( used the AC once last summer)
I would like to camp for longer periods( I am trying to convince my wife we should be full timers)
So the set up as I see it, 4 or 6 6v deep cycle batteries, a 2000w inverter( for microwave and coffee maker) and a generator for those times when AC is a real need.
To save money I will forgo an automatic transfer switch and just plug my shore power cord into the inverter, or generator, or shore power. When running the generator I will also run a charger to maximize efficiency, and while driving have a switch to allow the bus alternator to give a helping hand to the house batteries.
Eventually solar power will be added( when I convince the wife that full timing is a good idea) , what size wire should I take from roof to basement since I have the possibility of running them since it's almost gutted.
What's missing in my plan, what else should I plan for in the future, and what should I change. For those of you that did or re-did a conversion here is a pic of some of my wiring.
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi144.photobucket.com%2Falbums%2Fr179%2Frepare-brise%2Fbus%2FA0B730F6-F4F0-488D-869F-316AEB760EE5.jpg&hash=9f95ae9a05a14f973f1ec59bd770f39144729cd6)
With a nice wiring job like that, i think oil fired lanterns would be the ticket or a bike with a alternator attached for the heavier loads. Nice race cars bet they are a blast. ;D
We race vintage road race cars, I restored this car last winter for my friend who is the driver/owner (Lives in St. Bruno on the south shore of Montreal.) http://s278.photobucket.com/user/cchs79/library/Lola%20T492?sort=3&page=1 (http://s278.photobucket.com/user/cchs79/library/Lola%20T492?sort=3&page=1)
Yvan did you sneak by and take pictures of my wiring job on huggy
uncle ned
Quote from: bevans6 on October 14, 2014, 08:00:00 AM
We race vintage road race cars, I restored this car last winter for my friend who is the driver/owner (Lives in St. Bruno on the south shore of Montreal.) http://s278.photobucket.com/user/cchs79/library/Lola%20T492?sort=3&page=1 (http://s278.photobucket.com/user/cchs79/library/Lola%20T492?sort=3&page=1)
Tell your friend if he ever needs anything detailed to come and visit, I always give discounts to racers, since we are all poor. There is only one way to become a millionaire in racing, start with 2.
Nice work Brian. What course?
We ran at Mosport (now Canadian Tire Motorsport Park) and Le Circuit Mont Tremblant this year, only two events.
Brian