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vermilye · 08-31-2010, 08:56 AM

Well, you learn something new every day. From a discussion of the same topic on another forum, I found the Minnesota Electrical Code is available on line in a number of formats, including as a PDF, On-Line Reader (Better than the one used by the NEC), Text, Kindle, etc. Since it is based on the 2008 NEC with additions be the state, and includes the 2008 version of the NEC, it is an easier way to view the code.

Minnesota Electrical Code

Nonno · 08-31-2010, 09:30 AM

I agree with installing 50amp but may I suggest something else to consider while the ditch is open. This may apply more to winter situations, I know you said you would not be there, but could also help at other times of the year. Run another cable that would allow your generator to connect with a transfer switch providing power to the house during power outages. I didn't think of this until after my 50amp installation was done.

Renipladlo · 08-31-2010, 02:02 PM

OK - First if the power in the house/barn is there enough spare amps to support it. If so do the 50AMP receptacle.

Next RV's are different when hooking up RV plug than a regular home, so you must make sure the electrician knows the differences, because if it's not wired correctly, you can fry all your coaches’ electrical systems.

http://www.myrv.us/electric/ - See this link and understand it well.

This link explains the differences, so I will try not to confuse his description. Just remember the ground and neutral do NOT BOND in the RV. They bond at the pedestal (shore power post in RV park) or in this case at the electrical panel where the power comes from. If you run separate line from street, you will also need a new meter base, etc, pay an additional meter reading charge, and maybe more.

Hope this helps.

Jocat54 · 08-31-2010, 06:15 PM

Quote:

Originally Posted by JohnQ

I just completed the job you are contemplating. The concern for the "Supplying Panel" is spot on, make sure that when you are installing the subpanel (that is what you are installing), the main panel has the "Juice" to coin a pun. I came out of my Main Panel with a 50 AMP 220 Breaker. The wire is 10/3 UF, no need for conduit, 105 feet to a "Mallard RV Subpanel" that I had one of the 220 hot leads (makes it a 110) to a 110 30 amp RV plug, and the other 220 hot lead feeds my wife's green house thereby killing 2 birds with one stone and a lotta Wifey Brownie points. I would also suggest that since you have a trench dug & open you also install a water line with a Frost Proof faucet (if you are in Southern Maxisnowta, and forget it if you are in Nordern Maxisnowta - Born and raised in Burrrrrrrrrrmidji). The 30 amp service is more than adequate for my coach here at home (hardly ever need a/c).

Hi John,
Am I reading this wrong? 10/3 is only good for 30 amps and you have a 50 amp breaker on the line? Not meaning to start anything here--it just caught my eye when I read the post.

John

vectra96 · 09-01-2010, 07:15 AM

One thing to consider when you look at the available service, if it will not support 50 amp service, you can consider installing 30 amp service (4 wire) wired like it was a 50 amp service. 30 amp two pole breaker, smaller wire, 50 plug outside. Still can put a 20 amp recepticle outside. Remember most generators only put out 120 volts from two windings. For 7.5 kW generator, each winding is only good for 31 amps, for a total of 62 amps. What size is your generator and what size are the output breakers?

I have 50 amp service in the RV and use the 30 amp method at home. I could pull the wires out of the conduit to the garage, put in new wires (legal fill in conduit), and put an outlet in the garage. Garage now has 240/120 Volt, 30 amp service.

RickO · 09-01-2010, 08:04 AM

Quote:

Originally Posted by vectra96

One thing to consider when you look at the available service, if it will not support 50 amp service, you can consider installing 30 amp service (4 wire) wired like it was a 50 amp service. 30 amp two pole breaker, smaller wire, 50 plug outside. Still can put a 20 amp recepticle outside. Remember most generators only put out 120 volts from two windings. For 7.5 kW generator, each winding is only good for 31 amps, for a total of 62 amps. What size is your generator and what size are the output breakers?

I have 50 amp service in the RV and use the 30 amp method at home. I could pull the wires out of the conduit to the garage, put in new wires (legal fill in conduit), and put an outlet in the garage. Garage now has 240/120 Volt, 30 amp service.

Thanks Vectra. Actually, this may be the best approach for me but I'll wait to see what I find when I can inspect the panel. If nothing else it could provide an option to use 6/3 grounded wire rather than 4/3. I had heard others refer to this option in the past but didn't understand it until these past few days of education.

Is your reference to the generator to make the point that this approach with 30 amp would provide virtually the same power? Mine is an Onan 8000.

vectra96 · 09-01-2010, 09:15 AM

Yes, for the generator at 8 kW, you get 33.5 amps per side available. You could even consider a 35 amp main breaker because of the larger cabling, due to voltage drop.

Bob86ZZ4 · 09-03-2010, 07:50 AM

Rent a trencher. You want to go at least 18", better to go 2'. Easy work with a rented trencher. Except the rocks and roots will slow you down. I'm in St. Paul if there's anything I can do to help. I'd even come out and set up a lawn chair to cheer you on from. If you're close to the cities I've got a buddy that's a licensed electrician too. Might be able to get him to come out if not too far.

RickO · 09-03-2010, 08:22 AM

Thanks so much Bob but we're near Windom... about 180 miles from you. My FIL has an electrician who wired the new barn he put up and I'm going to talk to him about the job. thanks again...

moisheh · 09-03-2010, 08:37 AM

I am about to install a 50 amp service as well. A few cautions. #10 wire is way too small if you are going to run any heaters or AC. The receptacle that one poster suggested is correct but with one caveat. You should have a disconnect close to the receptacle as you should never connect or disconnect your rv from a live circuit. You can buy the box with a 50 amp and a 20 amp receptacle complete with breakers at Home Depot online for $109.00.

OneRVer · 09-03-2010, 06:46 PM

50 amp. You will have to run a insulated ground wire, neutral wire, and two hot wires from the main breaker. At the new panel you have to have a ground rod connected to the new panel. Keep the Neutral bar/bus isolated from the GROUND bar/bus and connect the ground rod to this ground bar. If you do not do this, you will have a ground loop which will cause problems. In the new panel connect the insulated ground wire and the neutral wire to the neutral bar. Connect all white wires, neutral, to the neutral bar, connect all green or bar wires, ground, to the ground bar. DO NOT MIX GROUND WIRES WITH NEUTRAL WIRES. If you do this mixing and have it inspected by L & I you will have to start all over. Not Good.

Question: Is your motor home set up for 50 amp service or 30 amp service. I am assuming your home is set up for 50 amps.

For a 100 foot run I would not go any smaller then 2 ga copper. In the box I believe 8 ga. for 50 amp and 10 ga. for 30 amp.

These cable must be at least 24" deep. 36" deep if you have them buried where you can drive over it. Unless in that area you have the cable's run thru a conduit, then 24" is alright.

I hope I covered it all. Good Luck.

I also recommend this panel. It is all set up and the ground bar and neutral bar are already separeted. Connecticut Electric 60 Amp RV Panel with 50A Receptacle, Breakers & GFCI Duplex - CESMPSC55GRHR at The Home Depot

EngineerMike · 09-03-2010, 07:52 PM

I've used this panel twice now. gives me options to connect either a 30 or 50A cord direct w/no adapters, plus the 20A GFI all in one. Feed it from a 50A 2 pole breaker since you don't connect more than one RV at a time.

#2 wire for 100 foot 50A run is overkill. #4 would be more than adequate keeping volt drop to less than 3%. Truthfully an RV could live nicely w/a 5% drop which would be #6, assuming your original house voltage is better than 115V.

OneRVer · 09-03-2010, 10:53 PM

Quote:

Originally Posted by EngineerMike

I've used this panel twice now. gives me options to connect either a 30 or 50A cord direct w/no adapters, plus the 20A GFI all in one. Feed it from a 50A 2 pole breaker since you don't connect more than one RV at a time.

#2 wire for 100 foot 50A run is overkill. #4 would be more than adequate keeping volt drop to less than 3%. Truthfully an RV could live nicely w/a 5% drop which would be #6, assuming your original house voltage is better than 115V.

Yep, that is the same panel I installed w/an 80 amp breaker at the main panel. Ran 1 ought aluminum.
I am sure you are right. I have a problem of always over killing when it comes to electricity. Always pay more then what I should also. But I do feel safer going this route.

Also during during family reunions I end up using both the 30 and 50 amp breakers.

JimM68 · 09-04-2010, 08:06 AM

Quote:

Originally Posted by RickO

Thanks so much Dirk... that's perfect. I was surprised to see that the wire sizing chart calls for #4 wire for a 120v 50amp 100 foot run though. Hmmmm.... they seem to call for a much heavier wire that most on this thread have proposed.

ok good, nothing like some accurate reference material.

I did 50 amp 220 circuits for both an inground pool and a hot tub. (2 complete circuits) Used 6 guage wire, longest run was 30 feet.

The 10 gauge mentioned in other posts is WAY TOO SMALL for 50 amp, even for a 10 foot run. A hundred feet plus, you need some BIG wire.

It will cost you a grand for enough 4 conductor 4 gauge to reach 150 feet.

You "may" be able to skip the 4rth conductor. We did with the pool / hot tub. Oddly, code for a house says one and only one ground, at the main panel, everything else grounded off of that, but code for a pool says a separate bonding wire with a ground rod 10 feet into the ground.

So the cable coming out of the house is 2 hots and a neutral. (times 2)