RV Park Shore Power

[rpbuttery]

My coach is 50 AMP.

Staying at a park site that has both 30 AMP and 50 AMP breakers, but only a 30 AMP receptacle.  Manager assures me the 50 AMP breaker delivers 50 AMP service to the 30 AMP receptacle, and there's no problem in doing that using a 50/30 dogbone.

Not knowing squat about electrical matters, and being a do no harm kind of guy, I'm just using the 30 AMP, but am curious, is he right?

[hermanmullins]

rp,

I would be susceptible to what his is saying. I am not an electrician but know enough to know that if you only have a 30 amp receptacle you should not have two breakers. you can have a 30 amp receptacle that has the hot leg on a 50 amp Breaker. But what happens to the 30 amp breaker.

Now he may have a 30 amp and a 15 amp receptacle and that may be on 50 and 30 amp breakers. Then my question would come down to wire gauge, is  either heavy enough to carry the loads.

He was partly correct about the dog bone. if you have 2 30 amp receptacles and you use a dog bone you will have 2 30 amp legs with a max of 60 amps total. however if you use a dog bone with a 30 amp and 15 amp receptacle you only have a total of 45 amps. which is not enough to run more than one appliance and some cases even not then.

In my thinking using an adapter to take a 50 amp plug down to a 30 amp is your smartest chose. 

Herman

[wolfe10]

Sounds like he is using voodo math.

The two are not closely related.

A 30 amp RV outlet has ONE HOT, a neutral and ground.  Provides up to 30 amps @120 VAC.

A 50 amp RV outlet has TWO HOTS, a neutral and ground.  The two hots are from opposite sides of the box, so 240 VAC between the hots.  Provides up to 100 amps @ 120 VAC.

I would DEFINITELY check the outlet with a voltmeter before plugging in!

[kaypsmith]

Look at the breaker on the box, if it says 30 amp it has one switch, then he is only providing 30 amps. If you choose the 50 amp, again look at the breaker, if one switch (not one with two that are tied together", yes it is 50 at 120 volts, not 100 total amps at 120. This is NOT 50 AMP RV SERVICE.

If the the breaker is 50X2, tied together, and there is a 30 amp receptacle, this is not legal, and with a dogbone attached, it is wired for 240, the dogbone will trip his 50 amp breaker. And as Brett said, with no power cord attached to the receptacle, switch off the 30 amp and on the 50, using a voltmeter, check the two wide blades, if reads 110/120, and the narrowest blade to round reads 110/120, and the opposite wide blade reads 0, you can assume that there is 50 amps 120. Not very efficient for the campground owner, and you will be limited to 50 amps total, and also remember that the dogbone is only rated at 30 amps because that is the size of the male adapter.

My preference, look for an adequate campground.

[BillAdams]

3 hours ago, rpbuttery said:

My coach is 50 AMP.

Staying at a park site that has both 30 AMP and 50 AMP breakers, but only a 30 AMP receptacle.  Manager assures me the 50 AMP breaker delivers 50 AMP service to the 30 AMP receptacle, and there's no problem in doing that using a 50/30 dogbone.

Not knowing squat about electrical matters, and being a do no harm kind of guy, I'm just using the 30 AMP, but am curious, is he right?

Liar, liar, pants on fire!  You simply cannot provide 50 amp service (100 amps available for use) from a 30 amp plug.  The 30 amp plug has only 3 connections.  They are Hot, Neutral and Ground.  50 amp service provides TWO hots plus a Neutral and Ground.  Even if the park owner has put 50 amp breakers on the 30 amp line it would still only provide a total of 50 amps to your coach and not 100.  The fact that anyone would suggest that they have installed wiring that can provide either service from the same connection is either crazy or, as suggested earlier, a liar.  Just to make sure you understand, even if the park could push all those amps through their wiring, you coach wiring would not allow it.  Once you plug in your 30 amp dog bone you will only have 30 amps of usage available before breakers start tripping.

[RodgerS]

Below is an illustration of a power pedestal.  See wolfe10's response for the appropriate electrical setup and his suggestion about testing. You need to test for polarity and voltage. 

Note that starting from the left there are two 50 amp breaker switches. The reason they are there is that you actually receive two 50 amp legs off the left 4 prong plug, as wolfe10 said. 

There are two types of dog bones (30 male, 50 female OR 30 female, 50 male). 

"Not knowing squat about electrical matters," means you need to be skeptical about representations...Just remember, they may not be accountable or liable for their representations. None of the forum members are and neither am I. 

Consider getting some appropriate RV electrical training and upgrading your knowledge.

 If you screw up, you can expect upwards of $3,000 to $6,000 of damage to your coach.

You should have power protection installed as well for (and also use it wherever you store your RV...even your house):

• Surges
• Mis-wired Electrical Pedestals
• High & Low Voltage
• Other Miscellaneous Electrical Problems

If you screw up we will all commiserate with you, but personally I will be happy it is not me screwing up. 

Rodger S. 

[whiteeagle]

I would make and always use one of these 50A testers before plugging in to a "even remotely questionable" 50A receptacle.... believes it tells you everything to need to know to be sure of the wiring....

[whiteeagle]

I have (since these diagrams) changed the analog line voltage meter our and use two small digital meters that fit side by side on the two top outlets...

By using this, have found a couple campgrounds using fake 50A circuits to a supposed 50A outlet.... and by watching this while in a receptacle on a source common to others, have discovered widely fluctuating voltages responsible for others having their system tripping, etc.

Obviously can be used on 30A receptacles also with an adapter and will tell same info except both sides would/should always read same.

[wolfe10]

And a very good "already made" one-- even tells you in English if it is OK and if a problem, exactly what it is:http://50amppowerpal.com/

 

 

[manholt]

Thanks, Brett, for the reminder...I guess I need 2.  Left the other in NE Texas, when they changed out our system and gave me a brand new pedestal.

[jleamont]

I run the Power Pal Brett mentioned above, I keep it next to the drivers seat in a pouch. I grab it every single time before I plug in. I just wish it was louder when it is speaking, sometimes it gets drowned out with background noise. If you are getting two 120 legs from a 30 amp 3 prong outlet its wired like a clothes dryer .

[wolfe10]

9 minutes ago, jleamont said:

 If you are getting two 120 legs from a 30 amp 3 prong outlet its wired like a clothes dryer .

And, that would let the smoke out of all your appliances!

[jleamont]

Just now, wolfe10 said:

And, that would let the smoke out of all your appliances!

It sure will

[RodgerS]

This may be a bit too much information, but there really are a lot of basics one should learn if you are gonna avoid creating more problems. 

Here are just a few:

1) you have three electrical systems in an RV: a) 12-volt DC automotive system,  a 12-volt DC coach system, and c) a 120 volt AC coach system. 

2) as to the 120 volt AC coach system: The neutral and ground in an RV electrical load center are not bonded together (known as a floating Neutral condition): the RV chassis is therefore isolated from ground. So, an RV needs to be connected to, and in fact relies on, a good ground from the pedestal when you access 120 volts AC from a pedestal/home hookup. 

(Hot skin conditions are worth learning about as a concept and how to identify, even if some wish to argue that such conditions are rare in practice.)

So part of the analysis and good owner RV practice is verifying you have a good ground, in this instance, via the pedestal.  

Note: if you bond the neutral and ground in the RV, you have a floating Ground condition (vs a floating neutral as mentioned above) = this can cause nutty things to happen in your RV.......IF you also then connect to a pedestal that has reversed polarity you can become the pathway to ground for 120 volts AC, particularly if you are standing on wet ground and place your hand on a metal part of your RV.

Rodger S. 

[manholt]

You become the "Sparkler of the day"!  Well put.

[kaypsmith]

Yep, you won't need any light bulbs that day.

[hermanmullins]

White Eagle 

I made my own tester like in your picture.

I keep it in the power bay and always use at each and every place we patk.

I also made one for 30 amp. And have used it many times at Six-State when someone says that their power is off. 

Herman 

 

[jleamont]

The fact that you just don't see a 30 amp commercial tester always puzzled me. Maybe someone makes it now? Especially since that outlet by designwould be more commonly wired incorrectly. I always used my $17.95 volt meter and my plug in surge protector when we had a 30 amp coach. 

 

[BillAdams]

After having my coach "blown up" by bad electrical connections twice I "finally" installed a TRC hardwired like this:

https://www.amazon.com/Surge-Guard-35550-Hardwire-Protector/dp/B01AASJHGO/ref=sr_1_6?ie=UTF8&qid=1471996196&sr=8-6&keywords=trc+surge+guard

I could not be happier.

[jleamont]

Melted a bus bar in the breaker panel on the last coach and all of the wiring to the ATS. I learned the hard way . I have friends that still do not have any protection. They just don't seem to care.

[RodgerS]

"I have friends that still do not have any protection. They just don't seem to care."

My assumption would be that they are focused on enjoying their RV and don't want to waste the time to learn the electrical nuances or educate themselves, as Carl has explained to me. 

In parallel, when I worked at an RV dealership, they were happy to get the pedestal ruined RVs in the door and were not enthusiastic that I was trying to sell electrical protection devices to their customers. 

I suspect that part of the reason there are good used values out there is that some buyers, once they have gotten past their basic warranty period, just want out of their RVs. They really don't want to deal with all the repair, maintenance, add ons, and upgrades that help keep the dream alive owning a used out of warranty motorhome.

I have a long list of things to buy, beyond all the inspection requirements, that I consider part of good owner practices if and when I purchase a used-to-me motorhome. And no, I'm not in any hurry to get on the road...just yet...and my wife is not pushing me.

Rodger S. 

[manholt]

Joe.  Even if you are "hard wired, like BillAdams", it's still necessary to test the incoming juice...mine came with a built in Surge Protector, but I still put one on the pedestal. Especially at FMCA Rallies! 

[jleamont]

Carl, same here. I have a progressive built in, TRC hanging on the tower. I'm going to be honest....I had no idea there was one hard wired and I bought the TRC when I got the coach. I will say the TRC has the latest technology and it trips faster than the Progressive, plus it displays why it tripped.

[manholt]

Joe. Back in it's time.  You have a top of the line HR and they built the coach as best they could 14 years ago, so it does not surprise me.  Redundancy can be a good thing!

[RodgerS]

(Edited) I put up a link on how to build a load tester, but I think that may be a bridge too far. 

Regardless, some problems only show up under load testing - having one 50 amp leg drop off for example, and most testers are no load devices. 

---------------

As always, you are on your own, especially if you can't take the time to read a basic electricity book AND followup with an RVIA electricity course.

You also should read all the articles in the No Shock Zone website...plus many more sources.

I recommend: 

Electricity Demystified, Second Edition

Jan 10, 2012

by Stan Gibilisco

 

Yes, I know Carl, you boys just wanna have fun. 

Rodger S.