Reply
 
Thread Tools Display Modes
 
Old 02-09-2009, 07:30 AM   #1
Mini-Skoolie
 
Join Date: Jan 2009
Location: Prescott, AZ
Posts: 53
Year: 1997
Coachwork: Carpenter
Chassis: Spartan
Engine: Cummins 5.9
Electrical system - does this schematic look right?

I've been trying to figure out how all the electrical stuff in a bus conversion would tie together. I have a couple different ideas on how it could be done, but I figure I'll start out with the simpler one. I have some plans for a smarter, more complex, custom built system as well, but I want to see if there are any flaws in my basic reasoning before I try to work out all the details on that. So does this schematic of the simpler system look right? Am I leaving out any recommended safety components, or is there anything else that doesn't seem correct?

Comments on a couple of things that might look weird: I want this to be able to work with any power source from 15A to 50A. I also designed it to use a separate inverter and charger, because they're a lot cheaper than the combined inverter/chargers.

Anomalous is offline   Reply With Quote
Old 02-09-2009, 02:06 PM   #2
Bus Geek
 
the_experience03's Avatar
 
Join Date: Feb 2006
Location: Saint James, MN
Posts: 2,669
Send a message via MSN to the_experience03 Send a message via Yahoo to the_experience03
Re: Electrical system - does this schematic look right?

Nifty. It looks right to me. I think the vast majority of your components can be lumped together in a converter/charger setup which will automatically transfer power, charge the batteries, surge supression, and supply both 120vac and 12vdc. Also, why the all the different inputs? For 30 amps and under you can get away with having a 30 amp input and adapter cords. I understand wanting to be protected on that side by individual breakers, but I'm not sure that it will be necessary. You could use just a single 50 amp breaker. If the outlet is a 30 amp you can be pretty well sure that it has its own breaker. Actually, almost all that I've seen are even GFCI protected and trip rather easily.
__________________
http://farm4.static.flickr.com/3024/...09f20d39_m.jpg
Skooling it...one state at a time...
the_experience03 is offline   Reply With Quote
Old 02-09-2009, 02:29 PM   #3
Mini-Skoolie
 
Join Date: Jan 2009
Location: Prescott, AZ
Posts: 53
Year: 1997
Coachwork: Carpenter
Chassis: Spartan
Engine: Cummins 5.9
Re: Electrical system - does this schematic look right?

My thought on the multiple inputs was that I wanted separate breakers to avoid overloading a 15A or 20A source. It would be pretty easy to do with multiple appliances, air conditioner(s), etc. It would of course be very bad to melt wires, plugs, or outlets. Even if the power source has it's own appropriately sized circuit breaker, it would be a lot easier to reset a breaker inside the bus rather than having to go outside to locate the external breaker.

Of course, maybe this is all unnecessary. I've never even seen the inside of an RV, and certainly haven't been to a lot of RV parks or camping sites with electrical hookup. Perhaps the 30A and 50A connections are so common that I shouldn't bother with 15A and 20A? On the other hand, it might be nice to have the option of hooking up to power from a regular house, which probably doesn't have spare high current circuits available.
Anomalous is offline   Reply With Quote
Old 02-09-2009, 03:57 PM   #4
Mini-Skoolie
 
Join Date: Jan 2009
Location: Prescott, AZ
Posts: 53
Year: 1997
Coachwork: Carpenter
Chassis: Spartan
Engine: Cummins 5.9
Re: Electrical system - does this schematic look right?

the_experience, your post got me thinking and I realized that there were some things I had forgotten or could change.

1) Even if I want to keep individual breakers for all the inputs, a breaker on the 50A line is redundant. The master breaker in the 120V panel will probably be a 50A breaker. The only reason to have a higher rated one in there would be if I planned to pull more than 50A from either the generator or the inverter, which is unlikely.

2) The breakers on the input lines should actually be a little bit smaller than the rating, so that they will pop before an external breaker does. However, it seems that 14A, 19A, and 29A breakers are not very common. Is there any other way to ensure that the on board breakers trip before any external ones?

3) I forgot to add a circuit tester into the system. I've read that it's fairly common to find outlets in RV places that are mis-wired, so this is a good thing to have. I moved the switches around a bit, so that the circuit can be tested without connecting to the rest of the system.

Here's the updated schematic:


edit: I forgot to answer the question about why I don't just use a pre-made integrated system that will do most of this. The reason is cost. Maybe I'm looking in the wrong places, but from what I can see, an integrated solution will cost $1000 - $2000 more than buying separate components.
Anomalous is offline   Reply With Quote
Old 02-09-2009, 10:27 PM   #5
Mini-Skoolie
 
Join Date: Jan 2009
Location: Prescott, AZ
Posts: 53
Year: 1997
Coachwork: Carpenter
Chassis: Spartan
Engine: Cummins 5.9
Re: Electrical system - does this schematic look right?

Quote:
thanks for the schematic and questions... I was just wondering today why I can't seem to find a schematic anywhere! I do have a question though about the integrator that you suggest costs between $1K-2K... is there a name for this unit? If I were to look it up online what is called?
Here's an example of a unit that integrates an inverter, charger, and automatic transfer switch: http://www.invertersrus.com/pwrups6000w.html. This particular one costs $2300, but would greatly simplify the setup. More generally, you can look up "inverter/chargers" and "automatic transfer switches".

Quote:
Again, thanks for the awesome schematic! Do you have much electrical experience? Where did you go to find this stuff? Curious.
I have a tiny bit of experience with electronics, and basically no experience with electric wiring. I've swapped out a wall switch before, and that's about it. I do know how to read schematics, and I've done a lot of reading about electrical systems for RVs. I lack practical experience though, which is why I'm posting here to double-check my ideas.

Quote:
As for the question about what kind of breakers to use, I still don't see why you wouldn't use a 15 amp breaker for a 15 amp circuit... as you said you can't find 14 amp breakers anywhere. I'm pretty sure this would be the right approach, no?
My thought here is that it would be very easy to overload a 15A or 20A supply to the whole vehicle, so I want to be able to reset the breaker with a minimum of hassle. I would assume that there is some circuit breaker on the external supply circuit already, but that might not be convenient to get to. If there are two circuit breakers in series, and they are the exact same value, which one would trip first? As far as I can see, there's no way to ensure that the one in the vehicle goes first unless it's a lower value. That's why I thought that breakers slightly under the standard values might be useful. As far as safety goes, using standard breakers should be no problem.

The scenario is something like this: let's say I'm parked at a friend's house, plugged into a 15A circuit because that's all they have available. It's 2AM, everyone in the house is asleep, and the circuit breaker is down in the basement. I momentarily forget that I'm plugged into a puny 15A supply, and try to run the microwave while the air conditioner is already going. Oops, breaker trips. Now, if I have a 15A breaker in the bus and there's a 15A breaker on the supply circuit, it seems to me that there's a 50/50 chance of tripping the breaker in the basement of the sleeping house rather than the breaker in the bus. I'd much prefer that the breaker inside the bus be the one to trip, but I don't see any way to do that short of using some odd valued circuit breakers. I suppose I could use a 10A breaker on a 15A circuit, 15A breaker on a 20A circuit, but that would severely reduce the available current in a situation where it's already too low.

My ideas for a more complex system would address this, but it's a lot more complicated to put together, and possibly more fragile. I'll have to see if I can draw up a schematic for this soon. It basically involves using a series of sensors, relays, and a micro controller to tie them all together.
Anomalous is offline   Reply With Quote
Old 02-09-2009, 10:38 PM   #6
Skoolie
 
Ray_WA's Avatar
 
Join Date: Nov 2008
Posts: 193
Year: 1991
Coachwork: BlueBird
Chassis: GMC
Engine: 6.2 liter diesel
Rated Cap: 24
Re: Electrical system - does this schematic look right?

I'm not an electrician... but it seems to me that if the breakers are identical the one in the house will blow first because it is pulling slightly more load. The circuit breaker in the bus only carries the juice that makes it that far.... there is wiring between the bus and the circuit breaker in the house and that wiring adds some load to the breaker in the house.... the longer the run from breaker to bus the more drop there will be and the more likely this will be. If I'm wrong, someone please correct me.

-Ray
__________________
Pack up your bus and bug out to the hills!
Ray_WA is offline   Reply With Quote
Old 02-09-2009, 10:47 PM   #7
Mini-Skoolie
 
Join Date: Jan 2009
Location: Prescott, AZ
Posts: 53
Year: 1997
Coachwork: Carpenter
Chassis: Spartan
Engine: Cummins 5.9
Re: Electrical system - does this schematic look right?

Here, I put together an even simpler schematic in case anyone else is interested. This isn't something I'd use, but it should be a good base to start customizing from.

These are the differences compared to my previous schematics:
  • Only one input, 30A.[/*:m:1frs76vt]
  • Integrated inverter/charger/transfer switch, which is simpler to hook up but more expensive.[/*:m:1frs76vt]
  • No solar power.[/*:m:1frs76vt]
I do still have a separate circuit tester and surge protector. The inverter/charger/transfer switch may be able to perform these functions, but I'd rather not risk that expensive piece of equipment on a bad connection.

Anomalous is offline   Reply With Quote
Old 02-09-2009, 10:50 PM   #8
Mini-Skoolie
 
Join Date: Jan 2009
Location: Prescott, AZ
Posts: 53
Year: 1997
Coachwork: Carpenter
Chassis: Spartan
Engine: Cummins 5.9
Re: Electrical system - does this schematic look right?

Quote:
Originally Posted by Ray_WA
I'm not an electrician... but it seems to me that if the breakers are identical the one in the house will blow first because it is pulling slightly more load. The circuit breaker in the bus only carries the juice that makes it that far.... there is wiring between the bus and the circuit breaker in the house and that wiring adds some load to the breaker in the house.... the longer the run from breaker to bus the more drop there will be and the more likely this will be. If I'm wrong, someone please correct me.

-Ray
That makes a lot of sense to me, though I'm no electrician either.

Of course it's the exact opposite of what I'd like to have happen, but I'm afraid that nature does not often ask my opinion before enforcing the laws of physics.
Anomalous is offline   Reply With Quote
Old 02-11-2009, 09:48 PM   #9
Mini-Skoolie
 
Join Date: Jan 2009
Location: Prescott, AZ
Posts: 53
Year: 1997
Coachwork: Carpenter
Chassis: Spartan
Engine: Cummins 5.9
Re: Electrical system - does this schematic look right?

Vanguy, I think there's a lot to be said for simplicity. I can certainly see the advantage of a system that is simple to build, cheap, and unlikely to break down.

I'm afraid that I like complexity and gadgets though. Automation just appeals to me. I'm the type of person who would enjoy having their entire house wired for computer control. If I design something, I'd like it to be able to operate as independently as possible, with little or no human intervention.

This may be part of the reason that I start far more projects than I end up finishing.

I'll readily agree that complex systems are much more likely to break down than simple ones, but I think you're being a little bit overly dramatic about the failure mode of an automatic transfer switch. I find it hard to believe that a failed automatic switch is likely to end up connecting two separate sources, resulting in a fire or equipment damage. The only way I can imagine that happening is if it gets burned out by a serious surge (like lightning), but the upstream surge protector should prevent that.
Anomalous is offline   Reply With Quote
Old 02-11-2009, 10:52 PM   #10
Bus Geek
 
the_experience03's Avatar
 
Join Date: Feb 2006
Location: Saint James, MN
Posts: 2,669
Send a message via MSN to the_experience03 Send a message via Yahoo to the_experience03
Re: Electrical system - does this schematic look right?

I happen to run vanguy's solution. My inverters, gennie, and shore power connection are all isolated. I can run one circuit on inverter power and another on shore power, but I can never have the shore power AND inverter powering a single circuit.

I want to reiterate again that despite the inconvenience, you are far more likely to have to go outside to reset a breaker. I don't know why, but every campground I have been at has sime extremely sensitive circuitry, to the point that we had to drape a rain coat over one box when it started sprinkling thanks to the GFCI (and I KNOW the problem wasn't on my end). It sucks, but it's life.
__________________
http://farm4.static.flickr.com/3024/...09f20d39_m.jpg
Skooling it...one state at a time...
the_experience03 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Electrical System Switch Docsgsxr Conversion Tutorials and How-to's 8 03-31-2014 09:31 AM
Just starting: electrical system question BelltownBikes Electrical, Charging and Solar 10 03-18-2013 04:36 PM
My self-designed electrical schematic if anyone's interested MichaTheStoryteller Conversion General Discussions 3 02-28-2013 11:27 PM
interlock panel on electrical system adamanderr Conversion General Discussions 0 04-07-2008 07:59 PM
Electrical System Setup jnizzle Conversion General Discussions 9 01-30-2008 01:00 PM

» Virginia Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 01:25 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.