Can't get 50 Amp to come on

The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.

davem1958

Active member
Joined
Mar 16, 2006
Posts
34
I'm a relative newcomer, having owned my HR Vacationer for about 3 months.  I moved to a new spot today (same RV park), and now I don't seem to have 50 Amp service, judging by the electrical panel (it's all automatic).  The shore power has 20/30/50, and I'm plugged into a 50 Amp connection.  I ran the generator today and I don't know if that caused the problem, or if I just didn't notice the problem before I ran the generator. 

Any general suggestions how to get 50 Amp service "recognized"? 
How does the RV know I'm plugged into 50 Amp in the first place?

Thanks in advance!

Dave
 

Ned

Moderator Emeritus
Joined
Feb 1, 2005
Posts
25,107
Location
USA
Does your RV have a 50 amp power cord or are you using a 30A to 50A adapter?  How do you know you don't have 50A service?  If your power cord has a 50A plug (4 prongs vs. 3 on a 30A plug) then you have 50A service if the pedestal is wired correctly.

Running the generator has no affect on the shore power.
 

Alaskansnowbirds

Site Team
Joined
Mar 11, 2005
Posts
2,969
Location
Camp Verde, AZ
davem1958 said:
I'm a relative newcomer, having owned my HR Vacationer for about 3 months.  I moved to a new spot today (same RV park), and now I don't seem to have 50 Amp service, judging by the electrical panel (it's all automatic).  The shore power has 20/30/50, and I'm plugged into a 50 Amp connection.  I ran the generator today and I don't know if that caused the problem, or if I just didn't notice the problem before I ran the generator. 

Any general suggestions how to get 50 Amp service "recognized"? 
How does the RV know I'm plugged into 50 Amp in the first place?

Thanks in advance!

Dave

Dave,

Have you checked the 50 amp circuit breaker on the campground power pedestal? Most campers trip the breaker before they unplug the power cord.
 

davem1958

Active member
Joined
Mar 16, 2006
Posts
34
I'm plugged in using a 50 amp cord, 4 prongs.  I checked the circuit breaker also.  I know I'm getting power, since the heater is working.

I had a problem with the panel once before, so perhaps it's on the fritz?  There are lights indicating what kind of power I'm on - 20, 30 or 50.  Right now it's saying 30.  Being an engineer (electrical, no less) I'm just wondering how the panel knows -- I guess by the number of prongs I'm using?

Dave
 

Ned

Moderator Emeritus
Joined
Feb 1, 2005
Posts
25,107
Location
USA
What panel are you talking about?  I don't know of any device that will tell you the ampere capacity of the shore power connection.
 

John From Detroit

Well-known member
Joined
Apr 12, 2005
Posts
24,948
Location
Davison Michigan
Possible problems, how to diagnose them, and how to fix them

1: Blown breaker on camp ground side of things.... Visual inspection... if the breaker it tripped it should show tripped, Reset breaker... Method 2, does it work on generator still? If so re-check park breaker, re-check all plugs and connectons, and if you are lucky you will find it.

2: Tripped "Main" breaker in the "house",  Visually inspect.. NOTE: if this is tripped the generator won't wok either

3: Deffective transfer switch.. This one will require you use test gear, and locate the switch (happened to me on a brand new Motor Home)

4: Other, (IE: broken, loose wire),,, this happened to me too,  again, test equipment required
 

Tom

Administrator
Joined
Jan 13, 2005
Posts
48,729
Dave,

FYI the 50A service uses two hot legs from a split phase supply, a neutral and a ground. The panel can easily determine if you have 50A service because it sees 240V across the two hot legs. If one is missing, but the other shows 120V to neutral, it assumes you're plugged into 30A. It sounds like one of the hot legs is missing. The 50A service should have two breakers at the power pole, one for each hot leg.

Do you have an inverter? If so, the power from the pole comes in via the inverter and it's possible one of the breakers on the inverter has tripped.

Another place to check might be the main breaker panel inside the RV.
 

Tom

Administrator
Joined
Jan 13, 2005
Posts
48,729
Ned said:
I don't know of any device that will tell you the ampere capacity of the shore power connection.

Ned, the energy management system in our coach does exactly that. The only thing it can't tell is the difference between being plugged into 20A or 15A, so I have to manually override that one. In addition to telling me what I'm plugged into, it sheds/connects loads based on available power and also tells me how much current is actually being drawn.
 

davem1958

Active member
Joined
Mar 16, 2006
Posts
34
thanks again, all.  It looks like I have some investigation to do.  You answered my question about how the coach knows what power is available, so that's great to know.  I have a couple of other warranty items to fix, so I'll add this to the list.

dave
 

Tom

Administrator
Joined
Jan 13, 2005
Posts
48,729
If anyone is interested, here's the smart power management system I referred to. Scroll down to see the optional remote panel which shows the type of power our RV is plugged into and which loads are being shed and in which sequence.
 

Ned

Moderator Emeritus
Joined
Feb 1, 2005
Posts
25,107
Location
USA
Tom, I see how that might work, but I've never come across such a meter. ?If he is really plugged into a 50A circuit, then it should indicate such, unless the pedestal was miswired.

Relying on the voltage across the 2 hot legs to determine the amperage is not a valid assumption however. ?There would be no difference between 15A, 20A and 30A, they all would read 0V between the 2 hot legs, while 50A would read 240V, but it still doesn't tell you the actual circuit capacity. ?I've seen 50A sockets that had 30A breakers. ?You can't tell the circuit capacity from the voltage.
 

Tom

Administrator
Joined
Jan 13, 2005
Posts
48,729
Ned,

I think the real issue is that the meter tells you which type of receptacle you're plugged into. 15, 20 or 30A receptacles are all 120V systems and therefore will never show as 50A service because this is only available at 240V. 50A/240V tells the EMS that both legs can be used and this changes the loads that are connected or shed. It obviously can't, and isn't intended to, tell you if someone used 30A breakers on a 50A circuit or if someone used a 30A breaker on a 20A circuit. Something is wrong if either of those situations exists, maybe incompetence or ignorance on the part of the person who installed them.

Since Dave's system is indicating 30A, he appears to have only one leg powered, which might mean that one of a pair of breakers has tripped or one of the two hot wires isn't connected - could be anywhere from the pedestal to the power cord to wherever. Of course, the EMS panel could be bad.
 

Ned

Moderator Emeritus
Joined
Feb 1, 2005
Posts
25,107
Location
USA
If only one leg is hot, then that's a fault and shouldn't indicate 30A, which would be if there were 0 volts between the hot legs.  If one one is hot, then that's not the case, and also only half the circuits in the RV would work.  I suspect it's a 50A receptacle wired with both legs on the same feed.  A simple check with a voltmeter would resolve the question.  Check each hot leg to ground and hot to hot at the receptacle.
 

Tom

Administrator
Joined
Jan 13, 2005
Posts
48,729
Ned said:
If only one leg is hot, then that's a fault and shouldn't indicate 30A, which would be if there were 0 volts between the hot legs.

That's how the "smart Y" works on my boat - if I use two separate 30A cords plugged into two separate 30A/240V receptacles on different legs to provide the 240V instead of a 50A/220V receptacle. The output of the smart Y box remains disconnected until both hot legs are present.

But I don't see how the EMS on the coach would know the difference between one leg of 240V missing and being plugged into 30A/120V - neither situation would show any voltage between the hot legs. Unless of course it's the "2nd hot leg" that's missing, then neither  50A/240V service nor 30A/120V service would "appear" to the EMS to be present. I re-read their brochure and couldn't see anything that suggested the EMS had the ability to determine otherwise.

I might drop them an email to ask the question because, as you say, it really is a fault condition.
 

Gary RV_Wizard

Site Team
Joined
Feb 2, 2005
Posts
73,954
Location
At our Silver Springs FL home
I agree with Ned. It seems likely the EMS is looking for 240V across the two hots and if the power pole is wired  with the hots in phase (120V max) then it would likely mistake 50A for 30A.  Need to check the voltage with a voltmeter to tell for sure, but it is not all that unusual to wire a 50A power outlet such that it actually has only 120V available rather than 240. Most rigs would never know the difference, since most don't use any 240V power.

30A looks the same as 50A inside the coach except for the max potential voltage because the 50/30 adapter puts 120V on both of the hots.

But the EMS must be a bit smarter than this if it can tell 15/20A from 30A. Those look exactly the same in terms of voltage and phase. Sure wish I knew how they do that!
 

Ned

Moderator Emeritus
Joined
Feb 1, 2005
Posts
25,107
Location
USA
RV Roamer said:
But the EMS must be a bit smarter than this if it can tell 15/20A from 30A. Those look exactly the same in terms of voltage and phase. Sure wish I knew how they do that!

Me too!? That would be a good trick.  The Intellic panel really can't tell the difference, it just has a switch to tell it 20A or 30A.
 

PancakeBill

Well-known member
Joined
Apr 9, 2005
Posts
5,934
Location
Benson - Tucson, AZ. West Yellowstone,MT
The system sees 240 as a result of 2 120 legs.  If one side of the 50A is dead, the rig will see 120 on one leg, 0 on the other and can see it as what a 30A would be.  I think you  guys know this but it didn't read that way. 

 

Karl

Moderator Emeritus
Joined
Mar 3, 2005
Posts
5,154
Location
Elkhart Lake, WI for the summer. Work at Road Amer
15,20,30 - it's all the same except for wire size and c.b. capacity. Do as Ned suggested and measure each hot to ground for 120V, and hot to hot for 240. If each hot reads 120 to ground but not 240 to each other, the two hots in the outlet are wired to the same 120V feed and your EMS will show 30A. If it does read 240, remove the cover from your breaker panel and measure each hot leg buss there for 120V each to ground. If one is missing, you've got a bad connection somewhere between your 50A plug and the breaker panel. If that's o.k., check for 120V on the load side of each main breaker for both legs. You may have a bad breaker. Wouldn't hurt to flip the breakers in your panel and on the pole  off/on a few times to see if that clears the problem. If you measure 240V between the load side of both main breakers and the panel still shows 30A, your EMS (or the wiring to it) is faulty. 
 

Ned

Moderator Emeritus
Joined
Feb 1, 2005
Posts
25,107
Location
USA
Not knowing the internals of the Intellitec, I don't know what it would read between a hot and an open leg, probably nothing. ?An open leg isn't 0V, it's no volts, as if it weren't there. ?Can't take a voltage reading with just one probe :)

That's why I didn't assume it would indicate 30A in that case.
 
Top Bottom