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Old 03-26-2006, 01:02 PM   #1
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Converting from 30 amp to 50 amp shore power

After reading up what little I could find about upgrading the shore power of my '94 Land Yacht and calling several Airstream dealers (none of whom knew anything about what I was aslking), I enlisted some help from a technical friend. We've just completed the bulk of the upgrade, and I can say that it's a dog's breakfast.

Firstly, the manual shows the basic configuration in block diagram form - no schematic is available. Nobody has a real schematic of the 120-volt system. My techie friend was able to trace the manufacturer of the ATS switches and get the schematics for the switches. Then, based on the new application, he had to redesign the two ATS switches keeping all the necessary safety mechanisms in place (eg - time delay relays on the generator side of the circuit to enable tht generator to power up to full output before placing the load on it). The fact that one of the time delay relays in my unit turned out to be defective sure didn't help the issue.

Anyhow, with the exception of the time delay relay that needs to be replaced and a new circuit breaker that needs to be installed on the 20-amp side, it's done.

Part of this project was a box that allows me to use 2 30-amp plugs where there is no 50-amp one. The box includes a test circuit to ensure that the neutral is common to both sides of the circuit by using a set of LED's. The so-called 120-volt 50-amp shore power is actually 240-volt 30-amp single phase, like what you have in your home, only nothing is meant to run on 240 volts.

Unless you have an excellent working knowledge of electricity (my tech friend sells and services hotel and restaurant equipment and has also been called in as a consultant to assist in relocating bakery manufacturing equipment), don't consider doing this on your own. The rewiring of the motorhome alone took 12 hours, and there was quite a bit of scrounging of parts involved (the most successful of which was 100-feet of 10AVG x 4 super-flexible rubber cased wire - I now have a 100 foot shoreline).
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Old 03-26-2006, 02:27 PM   #2
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Blkmagikca,

Congratulations on your wiring project.

There are schematics available for the 1999 Land Yacht. I don't know if any signifivcant changes were made between 1994 and 1999, but it would be a place to start.

The '99 model has 50a of 120v/240v power (3 wire w/gnd), not 30a 120v/240v. The power cord is 4 AWG, not 10 AWG.

If you want the link to the 1999 schematics, answer back.
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Old 03-27-2006, 06:26 PM   #3
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Schematics

Sure, I'd like to see the schematics. BTW, 10AWG meets the rating for 30 amp at 240 volts, so it really is adequate for the motorhome - the service you are plugging into is 30 amp 240 volt single phase (just like your house), and you are using 30 amps on one side and 20 amps on the other. 4AWG wire is quite big - must be about 2inches in diameter - that's heavy to handle. BTW, when my friend bought the wire (at a clearance house) he got me 100-feet - so I now have a 100-foot shore line - no need for extension cords.

I just took my unit to a repair shop to fix the generator - it packed out during the winter, and I suspect I burned out the starter. The repair shop tech hinted that I might also have fried the circuit board (I let it crank too long when I couldn't start it - bad me).

Gotta get it all together as we're planning on going to the Region 2 Rally.
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Old 03-27-2006, 09:02 PM   #4
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Thumbs down Not a smart thing to do....

Does your "friend" also have the qualifications to re-certify the motorhome so that it meets or exceeds the minimum required electrical standards that the manufacturer had to comply with?

Of course not.....

"Rewiring" a motorhome or a travel trailer involves a lot more than just changing things around.... the design & installation must be reviewed and approved by the manufacturing regulatory agency that oversees/oversaw the manufacture of it to begin with; or by a recognized inependent evaluation & testing agency.

What you did was just dangerous, impractical, & illegal...

How many public parks have two 30 amp 120 volt outlets at the pedestal for one site?

I hope you or future owners never have an insurance claim that necessitates evaluation of your motorhome by an insurance appraiser.....

Congragulations, you just modified your motorhome to the point of not being able to resell it to anyone else and essentially voiding your comprehensive automobile insurance.....
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Old 03-27-2006, 09:21 PM   #5
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Blkmagikca,

Here is the link to the Landyacht schematics:

http://www.airstream.com/airstream/p...UAL%202001.pdf

It is a large PDF file. Skip down to page 120 (power panel) and 122 (schematic). There is also some info on the ATS's but you need to blow it up pretty large to read it.

I'm afraid trulyvintage is right on about your project. As you will see from the schematics, the 50a 120/240v circuit need to be wired with #4 if you are going to plug into a 50amp RV connection.

Further, using two 30amp connections could be very hazardous if you plug it into two pedestals. If the two pedestals are not separate legs/phases, you will dangerously overload your neutral.

If the two connections are opposite phases, the neutral will carry the difference between the two legs. If they are the same phase, they carry the sum. You could have 60 amps returning though a #10 neutral wire. And that wire is not protected by a breaker.

Please rethink what you have done.
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Old 03-27-2006, 10:17 PM   #6
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As stated above new MH's come with the 4 ga wiring for a reason.
I would suggest you keep a close eye on the 10 gage as it will be getting "very hot" under full load.
Also they (50 amp RV's) use a single box ATS that has 2 sets of contacts built for the 220 VAC set up so the genset switches over both sides at the same time.

I agree with Markdone the 2/ 30 amp connectors can be a real problem.
You should be using a 50 amp to 30 amp adaptor at sites without 50 amp service.

Garry
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Old 03-28-2006, 01:11 PM   #7
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Let me address several points raised:

Firstly, my friend does have the qualifications to do this. He has designed, built, had CSA (and ETL) certified several types of commercial kitchen equipment that embodies both electrical (240v) and plumbing. The largest item was a muffin pan washer for a commercial bakery.

Secondly, he did consult with the electrical code and with a commercial supplier of wire as to what guage wire was needed. The 10AWG meets all the regulatory requirements for 240-volt 30-amp service (which is what my motorhame has). The rewiring was actually a redesign which took into consideration the fact that there is need for a timing delay (as built into the ATS 30 boxes) that will prevent the generator from being loaded before it is up to speed.

Thirdly, the adapter box that he made for me that would allow me to use two 30-amp connections has a full test circuit built into it - it tests to see that the neutral is common to both the lines. Similar units without the test gear built in are being sold by Camping World - see http://www.campingworld.com/browse/s...5&skunum=25774

The newer motorhomes come with "basement" type airconditioners that have a far different requirement than the two roof mounted 13,500 btu units I have. At the time my unit was built there was an option to have 50-amp shore line, but at the time many people did not avail themselves of this option (including the original buyer of my unit).

My unit came with two ATS 30 switches and it was set up so that when the generator is running, both air conditioners would run. The redesigned wiring extends that option to the shore line - it does not require a new ATS unit because the only thing serviced by line 2 is the rear air conditioner.

I will be monitoring the wiring to see if it gets warm under load - and if it does, it will only necessitate changing the wire.

Thanks to markdoane for providing me with a link to the manual for the 390XL manual - I wonder if the PDF file for my 1994 Land Yacht would also be available for download. I'll have to browse around to see if it is.

I do thank you all for your comments. This project was not undertaken lightly - I did research what i could on the web first and then enlisted my friend's help. I know he would not breech the electrical code - in fact his comment to me was that he disliked the use of solid copper wire throughout the coach as he feels that all mobile wiring should be stranded (he at one time installed avionics and is very aware of the damage that vibration can do to solid wire).
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Old 03-28-2006, 01:42 PM   #8
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Question Oh, now THAT makes a difference!

Quote:
Originally Posted by blkmagikca
Let me address several points raised:

Firstly, my friend does have the qualifications to do this. He has designed, built, had CSA (and ETL) certified several types of commercial kitchen equipment that embodies both electrical (240v) and plumbing. The largest item was a muffin pan washer for a commercial bakery.

I know he would not breech the electrical code - in fact his comment to me was that he disliked the use of solid copper wire throughout the coach as he feels that all mobile wiring should be stranded (he at one time installed avionics and is very aware of the damage that vibration can do to solid wire).

So, why not call Airstream & give them your VIN number & let them know about the modifications you have made.....then call your insurance company & talk to your agent.... let your agent know about the "improvements" you have made to your motorhome & perhaps you can obtain a rate discount!

I am confident that both Airstream & your automobile insurer will have no problem with a muffin pan washer designer & builder modifying the electrical system on your motorhome (I am sure they get calls like that everyday).... do you?

Oh, if you EVER go to sell your motorhome BE SURE to let the prospective new owner know about your approved improvements to the electrical system
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Old 03-28-2006, 02:20 PM   #9
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Quote:
Originally Posted by Trulyvintage
So, why not call Airstream & give them your VIN number & let them know about the modifications you have made.....then call your insurance company & talk to your agent.... let your agent know about the "improvements" you have made to your motorhome & perhaps you can obtain a rate discount!

I am confident that both Airstream & your automobile insurer will have no problem with a muffin pan washer designer & builder modifying the electrical system on your motorhome (I am sure they get calls like that everyday).... do you?

Oh, if you EVER go to sell your motorhome BE SURE to let the prospective new owner know about your approved improvements to the electrical system
Jim, you have made your point. The person originating this thread had the work performed by a qualified electrician, and is now fully aware of your opinion on the matter. If he chooses to disregard your advice, that is his right, just as it is the right of the Moderation team to edit posts and /or threads that go too far. Which will happen with the very next "muffin pan installer" post you make. We have let this thread go as far as we are going to without serious editing and deletions.
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