30 amp connection at a campsite

AStravelers said:

About the suggestion to add 50amp RV service in a house.

--  True RV 50 amp service is a pair of 50amp circuit breakers.  So in reality you are adding an additional 100amp load to the existing load in the house. 
--  A house has a certain total amp service built into the load panel(s).  That may be 250amp service or maybe more for a very large house.  My guess is that most houses could not take the extra 100amps as part of a building code legal install.
--  To have a licensed electrician come in and ask them to add an additional 100amp load, the first thing they are going to look at is to see if the house can take the extra 100amps.   
--  Chances are a dedicated 30amp RV outlet could be installed.

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The only limits to adding branch circuit breakers to a residential panel is any branch breaker cannot be more than 70% of the main breaker value.  House service is 120/240 volts so you have a dual main breaker of the service value, i.e. a dual 100 amp or a dual 200 amp breaker.  A dual 50 amp breaker meets this criteria since 50 amps is 50% of a 100 amp service and 25% of a 200 amp service.  And, of course, having the physical space in the box to add a dual breaker.

Total up the branch circuits on your house panel, I'll almost guarantee they add up to significantly more than the main breaker value.

The way it works is the main breaker (a dual 100 or 250 amp breaker) protects the buss bars inside the breaker box.  Draw too much total current and the main breaker blows.  Each branch circuit breaker limits the current on that branch to a safe value for the wire connected to it.

Don't forget the breaker size only determines the maximum current that can flow through that circuit.  Each 20 amp breaker isn't pulling 20 amps, your RV likewise won't pull the full 50 amps from each side of it's breaker.  If it does, it's OK as long as the rest of the house doesn't draw more than the load rating of the main breaker.

So yes, chances are you'll be fine adding a dual 50 amp RV breaker to a typical house breaker box.  As long as you have the free space to access two adjacent breaker positions to match the dual breaker feeding the RV outlet.

Good call getting the 50-30 dog bone.  This past weekend I stayed at a campground that only had 50 and 20 at the site.  Luckily I was prepared.

AStravelers said:

About the suggestion to add 50amp RV service in a house.

--  True RV 50 amp service is a pair of 50amp circuit breakers.  So in reality you are adding an additional 100amp load to the existing load in the house. 
--  A house has a certain total amp service built into the load panel(s).  That may be 250amp service or maybe more for a very large house.  My guess is that most houses could not take the extra 100amps as part of a building code legal install.
--  To have a licensed electrician come in and ask them to add an additional 100amp load, the first thing they are going to look at is to see if the house can take the extra 100amps.   
--  Chances are a dedicated 30amp RV outlet could be installed.

A 30amp circuit with a dogbone to the 50amp cord for the RV would run a single the air conditioner and the microwave.  That should work fine for temporary guests or to get your RV ready for travel.

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Thanks for the corrections to my assumptions in the earlier posts.  It does make sense that a 200amp C/B panel could contain more than 200 amps of circuit beakers, since not every C/B would pull the rated amps at the same time

Does anyone have a link to how many total amps (determined by the total C/B's installed) could be be installed in a 200 amp panel according to electric code.

touchracing said:

This past weekend I stayed at a campground that only had 50 and 20 at the site. 

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Interesting. Several members have warned that 50 only sites were out there but I have yet to see one. Makes sense I suppose, park owner figures everyone's got an adapter, why not save the money wiring all the sites with receptacles that are unneeded.

AStravelers said:

CAUTION, CAUTION, CAUTION!!!! 
Unless you have something unusual, household clothes dryers are 240V.  Anyone trying to wire up an adapter plug for an RV to plug into this outlet must be absolutely sure the adapter plug/cord only goes to one of the hot legs of the dryer plug.  Otherwise you will wind up with 240 volts to your RV.  RV's are 120V only. 
Another caution:  If you have a 3 prong dryer outlet and make an adapter to power your RV will not have a 3rd wire safety ground to your RV.  You only have the hot and neutral return wires.

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If you did plug into this std 240 volt outlet wouldn't a good surge protector prevent a 240 volt problem?

Several members have warned that 50 only sites were out there but I have yet to see one.

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I workkamped in one for two summers, and have stayed at a couple others.  They aren't real common, but not exactly rare either.  Upscale places get customers who mainly have 50A rigs anyway, so it makes sense for them. Mobile home parks are also wired that way, so those that offer RV sites may be 50A only or 50/20. 

If you did plug into this std 240 volt outlet wouldn't a good surge protector prevent a 240 volt problem?

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It would if "good" includes high & low voltage monitoring, but that would probably be the top line (most expensive) models.

JoelP said:

If you did plug into this std 240 volt outlet wouldn't a good surge protector prevent a 240 volt problem?

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A GOOD one yes Like a Progressive Industries HW-50C or PT-50C or the TRC Surge Guard equivalents yes. But there are many perfectly good surge guards that can not protect you against this type of mistake.

You need one that has a DISPLAy that shows Voltage and Current at the minimum. The ones with LIGHTS ONLY generally do not offer that protection.

I have just bought a travel trailer with the intention of using it as guest accommodation as we are on an acre plus lot and although I have it plugged in to the regular house 15 A circuit, have not even tried to turn on the a/c to test it. I do have a 30A outlet in my garage which I put in by extending the existing washing machine outlet behind it so that I could plug in an heavy duty air compressor. That set up has worked as I never run the washer at the same time as the compressor.
Would it be safe if I was to make up an extension cable to plug into that socket and then plug into the trailer?  Seems to me like a logical idea, but then I am somewhat electrically challenged,  so would appreciate any advice in that regard.

printman said:

I have just bought a travel trailer with the intention of using it as guest accommodation as we are on an acre plus lot and although I have it plugged in to the regular house 15 A circuit, have not even tried to turn on the a/c to test it. I do have a 30A outlet in my garage which I put in by extending the existing washing machine outlet behind it so that I could plug in an heavy duty air compressor. That set up has worked as I never run the washer at the same time as the compressor.
Would it be safe if I was to make up an extension cable to plug into that socket and then plug into the trailer?  Seems to me like a logical idea, but then I am somewhat electrically challenged,  so would appreciate any advice in that regard.

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No, No. The plug for the dryer is 30amp 220 volt.  Your camper is 30amp 120 volt. The plugs may look the same but the voltage is different.

Alaskansnowbirds said:

No, No. The plug for the dryer is 30amp 220 volt.  Your camper is 30amp 120 volt. The plugs may look the same but the voltage is different.

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I didn't see where he mentioned DRYER.  He simply needs to state exactly what he has and the measured voltage.

The poster didn't say dryer, but did say heavy duty compressor. There's a good chance that the outlet is 240 volts and that they need to check to be sure. Better safe than sorry.

He also said "by extending the existing washing machine outlet", but washers use standard 15A outlets, not 30A. The adjacent dryer, though, is probably 30A/220v.

printman said:

I have just bought a travel trailer with the intention of using it as guest accommodation as we are on an acre plus lot and although I have it plugged in to the regular house 15 A circuit, have not even tried to turn on the a/c to test it. I do have a 30A outlet in my garage which I put in by extending the existing washing machine outlet behind it so that I could plug in an heavy duty air compressor. That set up has worked as I never run the washer at the same time as the compressor.
Would it be safe if I was to make up an extension cable to plug into that socket and then plug into the trailer?  Seems to me like a logical idea, but then I am somewhat electrically challenged,  so would appreciate any advice in that regard.

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As you are "somewhat electrically challenged", use great caution. 

Assuming you are talking about a 240V 30amp circuit, which goes to a pair of 30amp circuit breakers.  It is possible to tap into one of the two 120V hot lines, and install a 30AMP RV outlet.  Be sure you have a separate neutral wire and a separate 3rd wire ground (the green or bare wire usually).  Be sure you understand what you are doing or hire a electrician to do the work.  Be sure the electrician KNOWS the RV is 120V 30 amp, not 240V 30amp. 

Wow so much information in this stream.  I am considering putting in a 30 amp or 50 amp plug out in the garage for when I need to plug in the camper.  It is good to have all this info in my head as I pursue this further. 

Thanks everyone. 

If you hire the job done put in a 50 amp outlet
Electricans do those right. 30's they often mess you up to the tune of a kilo buck or so

Well, on the one hand, if you put in a 50 amp, you are golden if, in the future, you acquire a bigger rig with 50 amp service.  Meanwhile, with an inexpensive 50 to 30 adapter, it will power your current rig just fine.

And John from Detroit is right.  The 30 amp outlet is practically a dead ringer for another one that is always wired for 230-240 volt service.  This often leads electricians to screw it up if they're not carefully thinking about it when they're working.

On the other hand, you are going to need MUCH thicker wires for 50 amp service, and 4 of them, not 3.  Given the current price of copper, and depending on how great a distance the electrician needs to run the wires, it can cost SIGNIFICANTLY more money to put in 50 amp service compared to 30 amp.

As for the electrician screwing it up, you just have to specify to him that he must show you, with his meter, that the outlet is delivering 120 volts, not 240, and that he won't get paid until it does.  Problem solved.

As a rule, the 220/240 volts are actually due to having 2 - 120v legs (+ a neutral and ground). Each leg is on a different "wave" so that when one is +, the other is -. The combination (when an appliance is connected across them) is the 220v.
50 amp requires heavier gauge wire than 30, which is bigger than 20, etc., but that is a question of current draw and resistance inherent in wiring.

With that said.... DO NOT ATTEMPT unless you are a qualified electrician!!!  You can cause all kinds of havoc not the least of which can be fire or death!