Power cord question

[Firestorm]

On my Cougar 299 rks
It has a 30 amp cord, With my power issues last weekend when it was 98 with high dew points. My question is can I use my 50 amp adapter on my 30 amp plug and plug into a 50 amp service line. and not burn anything up
this might eleviate power shortages that im having
Thanks
Bob

[MarkS]

Your trailer's breaker panel probably has a 30 amp main. So, you are limited to 30 amp there.

Plugging your 30amp cord into a 50amp outlet, there is risk that a damaged cord would not be protected. But, if it is damaged anyway...


Sent from my iPad using Tapatalk HD

[mikell]

Your only using 1/2 so 25 amps

30 amp single phase = 30 amps

50 Amp 2 phase is 50 amps per side unless I'm mistaken 100 Amps total

http://www.myrv.us/electric/Pg/50amp_Service.htm

[Bluewater]

You still only getting the 30 amps thru that anyway so no problem.

[buzzcop63]

Trailers wired for 30-amp service is only going to get 30 amps. Using an adaptor for 50 amps with the hope that fewer people might be on that line and thus you will get full 30 amps when attached to it? The park you are in has a max capacity for its total amp draw when that is exceeded voltage is going to drop. The best suggestion I can make is cut back on all appliances running, switch to gas if possible so that the A/C has as many free amps as possible.

[Bob Landry]

Your only using 1/2 so 25 amps

30 amp single phase = 30 amps

50 Amp 2 phase is 50 amps per side unless I'm mistaken 100 Amps total

http://www.myrv.us/electric/Pg/50amp_Service.htm

You are correct on one out of three.

When plugging into a 50A source using an adapter, there is still 50A available at the pedestal, but the 30A DPST in the trailer is still going to limit you to 30A.

50 A is still single phase. While there are two 120V legs 180 degrees out of phase with each other, two or three phase refers to the phase shift between voltage and current and is used in commercial applications to run very large motors. In 50A service, current and voltage are in phase with each other on both legs.

[Firestorm]

Thanks everyone
Think I will stick to running gas to the hot water heater and fridge then when running AC.sounds like my safe bet. When running air the other day my S/P showed me pulling 17 amps with all other breakers thrown while cooling
BP

[JRTJH]

Firestorm,

If the campground you're at has separate supply circuits for 30 Amp and 50 Amp lines into the connection box, you may benefit from using the 50 Amp adapter. Let's assume that there are more campers connected to the 30 Amp supply side and they are all using power. That will create a heavy load and draw down the available power causing a "brown out" condition and leave you with reduced voltage. If there are fewer campers connected to the separate 50 Amp circuit, with less demand, there will be less voltage drop and you could see higher voltages into your RV. Additionally, with higher amperage available on the 50 Amp side, you'd be more likely to have greater power available.

Keep in mind, you have a 30 amp main breaker in your RV so you can't draw any more than 30 Amps no matter what you hook up to outside, but if the voltage is higher on the 50 amp side, you could get "better" availability by using the adapter.

If, however, the 30 Amp side of the campground box is run from the same circuit as the 50 Amp side, the other campers will be drawing down available power from the entire circuit and you won't see any increased power availability. About the only way to find out is to plug into 30 Amps, check your input voltage, then plug into 50 Amps using the adapter and see if the voltage is the same or higher.

Remember, if you're using the 50 Amp adapter, your 30 Amp power cord and the trailer wiring is not protected properly until at the location where the power reaches your circuit breaker box where the 30 Amp main breaker is located.

[Bob Landry]

I've wondered about that also and have never seen a response on any forum pertaining to it.
Are the CG pedestals wired with a 10g a feed for 30A and a separate 6ga feed for 50A, or, are they fed with wire sized for 50A and the 30A plug simply branched off of the 50A outlet. If it's the latter, and there are enough users on that main branch to reduce the available voltage to the pedestal, then there is no benefit to using an adapter other than using an outlet that sees less use and is less likely to have burned or corroded contacts. I suppose it varies with the individual campgrounds and some of the CG owners would need to address this question.

[slewis95407]

RV pedestals are wired 50A 6ga wire to two buss bars. The breakers snap on the buss bars. 50A to both buss bars, 30A to one buss bar and 15A to one buss bar.

[Bob Landry]

If I'm reading this correctly, the same 6ga feed supplies all of the pedestal outlets with the same voltage off of a pair of 6ga wires and that voltage is dependent on the number of users connected to the circuit relative to that feed.
I suspected that was the case as it would be cost prohibitive to supply three individual outlets with separate power sources.
In this case, the only way for a 30A RV to realize the full 50A available would be to utilize the standard 30A outlet as you would normally and then se an additional 20A extension from the 20A outlet to power auxiliary equipment such as a second AC or space heaters in winter. That would utilize the entire 50A being supplied to the pedestal.

[fla-gypsy]

I regularly use a 50x30A adapter and find that generally the 50A plugs are in better condition and you can draw the full 30A from them. You are always limited by the main 30A breaker in the RV panel. Another advantage I find is if you do overdraw while using the 50A service for a 30A RV is the breaker in the RV will trip instead of the breaker at the pole. This makes resetting after dark or in bad weather more convenient.

[geo]

RV pedestals are wired 50A 6ga wire to two buss bars. The breakers snap on the buss bars. 50A to both buss bars, 30A to one buss bar and 15A to one buss bar.

Slewis is correct. In 50 amp service, the supply wire comes in and is connected inside the pedestal to two buss bars. However, this is standard 240VAC service - the supply black and supply red wires ARE 180 degrees out of phase! It's just like standard home wiring - the two hot leads come in to the supply panel and are wired to the "main breakers". Those are the two 50 amp breakers located in the center of the RV wiring panel. Those main breakers supply 120VAC to the breakers outward to each side. So, half the 50 amp RV is wired with "0 phase" 120VAC, and the other half is wired with "180 phase" 120VAC.

For example, on my Alpine, the two AC units were connected to the same side running off the same 50 amp breaker. When the second AC would start, the 50 amp breaker would trip. Simple solution, move the second AC to the other 50 amp leg (other side) and move a less current draw distribution line to where it was with the first AC.

So, for 30 amp service (and 20 amp plug), the 30 amp breaker and plug usually comes off the supply black lead. That means that the campground 30 amp service and 20 amp plug are usually all off only one side of the 240VAC supply! (Both off the same 50 amp supply black lead.)

RVs are not "wired" for 240VAC normally, because if they were . . . what would happen when one used a converter dog-bone to connect a 50 amp RV supply to 30 amp service! Big problems! RV owners who have their units wired for 240VAC know they can ONLY connect to "correct" 50 amp service!

I "see" the problems that can be caused by this service where we are located at this time. I have a Surge Guard 40250 ATS with remote on my fiver. At certain times, most always at night, the Surge Guard will cut off the supply to the fiver because of "over voltage". What I have found is that sometimes during the night, I will get over voltage on Line 2 (supply red) of 130-132VAC! The Surge Guard disconnects before any damage can be done for those appliances (bedroom AC!) can be damaged by the over voltage! Line 1 gets the heavy draw from both the 50 amp service and the 30 amp service! (The campground knows about this voltage problem.)

This is one excellent reason why one needs a surge guard protection device between the pedestal and the RV! Especially the RVs with 50 amp service!

Ron

On edit:

Might be interested in some posts from the past by Flyguy: http://www.keystonerv.org/forums/showthread.php?t=398&highlight=electric+panel&page=3

And, it has been a while since this has been posted on the Forum: http://dasplace.net/RVWiring/wiring.html

[Waterbug]

RV pedestals are wired 50A 6ga wire to two buss bars. The breakers snap on the buss bars. 50A to both buss bars, 30A to one buss bar and 15A to one buss bar.

And if someone inexperienced wired the park, all the 30 amp plugs could be on the same leg, causing an imbalance at the transformer. If the park is wired properly, every other 30 amp plug is wired to the opposite leg. That way, if the park were full of 30 amp trailers both legs would be equally loaded. (Or as near so as possible)

EDIT. The park probably isn't wired with 6ag wire. That would require a homerun to each pedastal. It is probably wired with a heavier guage wire running to a row of pedistals in series. The conductors probably aren't color coded, so the number of 30 amp circuits on each leg would be random but approaching 50% on each.

[Conntek]

If you are using an adapter to plug your 30A coach into a 50A service at the pedestal you must understand you cannot draw more than 30Amps of electricity. Your extension cord going to your RV will most likely have a 10AWG 3-wire cable and will most likely overheat.

If you draw to much power, hopefully your RV breaker will trip. If you have an RV cord surge protector, it will most likely cut the power. But I have seen both methods fail to stop electric current and cause the cord to melt. Or cause a fire.

[PND]

To make it simple - think of railroad track, each rail is a "hot" leg, add a third rail and that is the "neutral"(remember the old three rail track on your old model trains). Now the ties that run between the two "hot" legs(outer rails) are the pedestals in the camp. The "hot" legs are on a large breaker and a wire size calulated on an assumed load. The largest size breaker in the pedestal dictates the size of wire "tapped" off the main "hot legs"-50 amp-#6 wire. 50 amp plug uses the two "hot" legs and a "neutral" -this is called a split-phase system, and the 30 & 20 amp plugs use one "hot" leg and the neutral. When you use an adapter to run your 30 amp system off a 50 amp (30 to 50), the adapter is only using one "hot" leg. NOW if you run your 50 amp system on a 30 amp plug (50 to 30), the adapter uses one "hot" leg, but parallels the other leg in the adapter to your other "hot" leg in your shore power cable. This limits AC usage on a 50 amp unit to 30 amps. And on a 30 amp unit, you are still limited to 30 amps - EVENTHOUGH you are plugged into a 50 amp receptical. Depending on how many units are plugged into pedestals, and if they are 50, 30, or 20 amp you can get a voltage drop on one or both "hot" legs from over usage - imbalanced load.

I have not used the term "out of phase" for a reason. Remember I used the term "split-phase" - a single phase can not be "out of phase" with itself. In the power world we say their "polatities" are opposite. If you draw a single cycle sine wave - at the .707 point on the "positive" (upper half) and the same point on the "negative" (lower half), between the two .707 points is 240 volts. Note that the wave "positive" is in series with the "negative" wave. The middle (zero) is the neutral - from either of the .707 lines (RMS) to the "neutral" is 120 volts. Because they are opposite "polarity" that is why some people call it 180 degrees "out of phase".

In a purely resistive circuit, voltage and current are in phase (yes, I am using that phase word here because now we are comparing voltage to amperage). In reality, current will lag or lead the voltage, depending on what kind of load it is connected to. This is Vars or we call it reactive power.

PND

[PND]

If this works, I have attached a drawing showing the wiring for the different plugs.

PND

[MarkS]

Thanks PND for your diagram.

A 30 amp male to 50 amp female dog bone just jumpers L1 and L2 in the 50 amp connector to the L1 in the 30 amp connector. Right?

A 50 amp male to 30 amp female dog bone just connects L1 to L1. Right?


Sent from my iPad using Tapatalk HD

[rclark]

I found the electrical power cord information on this link to be very easy to understand and useful for RV owners: http://www.myrv.us/electric/ :)

[PND]

"A 30 amp male to 50 amp female dog bone just jumpers L1 and L2 in the 50 amp connector to the L1 in the 30 amp connector. Right?

A 50 amp male to 30 amp female dog bone just connects L1 to L1. Right?"



If I understand your question - yes! The adaper (dog bone??) is made so if you only have a 50 amp service in your RV, the 30 to 50 will only supply one "leg" (120 volt) to your RV. Unfortunately, this does mean you will have limited AC - best to run refer., hot water off propane. And if you go from a 50 to a 30, you still only get one 120 volt "leg". Even though the 50 male plug has all four "pins" (50 to 30 adapter), only one of the "hot legs" is acually wired. As in the drawing, the 50 amp female end of a 30 to 50 adapter has a internal jumper, to feed "both hot legs" in your RV with 120 volts. Because they have the same "polarity" (parallel), current from each "hot leg" become additive - ie 10 amps from one side, 15 amps from the other = 25 amps on the neutral.

What I work with is 130 volts DC, 120/240 to 230,000 volts AC every day, so I can get carried away. Hope this is not confussing to you. My wife just crosses her eyes, when I get going on electrical things.

PND

[MarkS]

Thanks PND,

Some of the things I have read made me wonder if I understood how the pedestal was wired. Also, I was not sure if RV parks typically got residential style split phase or commercial 3 phase from the pole.

[PND]

OK. The parks are probably feed 3 phase, then they can be broken down to 3 individual single-phase circuits that are then wired as a split-phase system. By splitting the 3-phase into single-phase circuits, we can balance the load to a degree (never exact, but the best we can). There may also be step-down transformers involved, but I'll keep it simple. If the park was prperly engineered there souldn't be voltage drop problems, but we have to remember, many parks were wired years ago, before we (RV'ers) started adding all our "power hunger" camping toys. You know, all the AC we must have, blenders for those umy drinks, the fireplaces inside (electric of course), hair dryers, TV's and on and on. So many parks are underwired for todays fun, and we get undervoltage and problems. :(

PND

[geo]

OK. The parks are probably feed 3 phase, then they can be broken down to 3 individual single-phase circuits that are then wired as a split-phase system. By splitting the 3-phase into single-phase circuits, we can balance the load to a degree (never exact, but the best we can). There may also be step-down transformers involved, but I'll keep it simple. If the park was prperly engineered there souldn't be voltage drop problems, but we have to remember, many parks were wired years ago, before we (RV'ers) started adding all our "power hunger" camping toys. You know, all the AC we must have, blenders for those umy drinks, the fireplaces inside (electric of course), hair dryers, TV's and on and on. So many parks are underwired for todays fun, and we get undervoltage and problems. :(

PND

PND -

Not to be argumentative, but I tend to doubt if many RV parks would pay the extra to get 208VAC-3Phase. I would suspect that most parks are getting the standard 240VAC-2Phase sine wave AC that you describe.

Ron

[PND]

That is possible for small parks, but I would be willing to bet that they and the larger ones would be three-phase primaries. There is just too much load for a 240 volt single-phase service and a utility (like mine) wouldn't allow it. You have to remember that they are feed from a min. of a 12Kv distrubution system, and some (like mine) are 26Kv. Three smaller pole top or one 3-phase padmount transformer is cheaper to supply than one large single-phase transformer. Local codes dictate how a park must be wired.

PND

[PND]

You said 208/120 volt and the phrase 240 2-phase. 208/120 is a "Y" connected system. You can get 240/120 from a "delta" system with a center tap on a phase. 2-phase systems have not been around since the 70's. We had some and it is a 4-wire system 90 electrical degrees apart. Our most common is the 3-phase 120 electrical degrees apart. Voltage stays at 120 degrees, but the current can shift in relation to its relative phase. Not uncommon to have a referance of 0 degrees for "A" phase voltage, but 180 degrees of "A" phase current. Welcome to my world.

PND

[jonbiker]

My experience has been with numerous RV Parks using a 50 amp pigtail for my 30 amp trailer is that I get a higher voltage reading than using a 30 amp Hughes Autoformer. I have 3 voltage meters in the trailer. two digital and one analog. I no longer use the 30 amp cord by itself.

[PND]

How much of difference is there. Hard to see how this can happen, but would need to know how the pedestals are wired. So many variables that are unknown to make a guess as to why.

PND

[PND]

Thinking about it for awhile - if the "park" is feeding the pedestals with different transformers for 30 and 50 amp recepticals, that could account for a difference in voltage between the 30 and 50 amp circuits. Again, without seeing an AC elementary of the location, it is hard to see what is causing the voltage difference. Unless you have a transfomer with boost-buck taps, the voltage will vary between transfomers. I have seen as much as 6 volts difference between transfomers.

PND