30A Shore Power Plug issue?? Not enough juice to RV

[briarbuck00]

Hello, my partner and I recently rewired an airstream with only 120V AC power connections (no battery). We have a lease at a campground so the airstream is staying there. No need for off grid/battery power.

We renovated the whole thing in our driveway with the original 30A shore power cord plugged into a 20A adapter and plugged into an outdoor outlet of the house. Everything worked fine and the air conditioner compressor kicked on. I have a breaker panel inside with separate circuits for each appliance- air conditioner, Fridge, then lighting connections.

We finally pull up to the campground after months of work. We plug in the same shore power cord into the CG pedestal 30A receptacle expecting to be cooled by air condition. That didn’t happen! We can hear the fan and compressor trying to turn on with a faint hum. My gut tells me there’s not enough juice flowing to kick on the compressor.

No tripped breakers. When we turned the air condition on, the lights on other circuits would get dim- almost like they were competing for the power- but they are on different circuits. I check voltage and got 120v readings from outlets, and the 30A pedestal.

The CG pedestal receptacle looks dirty, and I noticed my shore power plug has some corrosion on the bottom right prong. Could this be what’s causing the lack of power- given that the alternating current wouldn’t be firing rapidly and consistently across all circuits?

My plan is to get a dogbone connection to get the 30a shore power cord into the 50A pedestal receptacle. OR- get a new 30a shore power cord altogether and/or pair it with the dogbone.

Any other remedies I should try or any explanation based on previous experiences?

[ITSNO60]

You need to measure voltage at the RV before and when the AC is trying to start. If the campground voltage is sagging, which is not uncommon at older campgrounds in the summer, this could cause a big problem. The absolute minimum voltage recommended for your AC is 103.5. (I feel more comfortable around 108 minimum although NEMA and the AC manufacturer says 103.5 will not damage your 115 volt motor). I have seen dips into the 90's at an old campground which can damage your AC if allowed to continue.

If you had an EMS it would cut power at 104 volts to protect your RV.

Also the plug should fit fairly tight in the outlet, if not the connection can overheat and damage your plug. I carry a 50 to 30 dogbone in case I run into a loose 30 amp outlet.

Your other possibility is that coincidentally the AC malfunctioned between your driveway and the CG.

[LAWBC]

Your hp capacitor may have blown.

[Wanderings]

The contacts on your 30A plug are corroded enough to cause excessive resistance to the electrical current flowing to your trailer. If combined with bad connections in the female plug, this would reduce the voltage enough to cause the issues you've noted. The excessive resistance will cause the plug/outlet to overheat and melt down or even start a fire. The circuit breaker will not trip as the current flow will not exceed the capacity of the 30 amp breaker. Find some electrical contact cleaner and clean the contacts on your plug, then ask the park to inspect their outlet as well.


Often these issues with both the plug and the outlet are caused by plugging into a live outlet. You SHOULD ALWAYS turn the breaker OFF before plugging your power cord into the pedestal outlet. Better yet, before plugging in your power cord, first plug in an EMS/Surge Protector, turn on the breaker and let the EMS analyze the power supply. Only when the EMS clears the outlet as being properly wired and grounded, then shut off the breaker again and plug your power cord into the EMS. NOW you can safely turn on the breaker and power up your trailer.


A former park ranger who has replaced many a fried outlet...

[BikeCamper]

Originally Posted by briarbuck00

Hello, my partner and I recently rewired an airstream with only 120V AC power connections (no battery). We have a lease at a campground so the airstream is staying there. No need for off grid/battery power.

We renovated the whole thing in our driveway with the original 30A shore power cord plugged into a 20A adapter and plugged into an outdoor outlet of the house. Everything worked fine and the air conditioner compressor kicked on. I have a breaker panel inside with separate circuits for each appliance- air conditioner, Fridge, then lighting connections.

We finally pull up to the campground after months of work. We plug in the same shore power cord into the CG pedestal 30A receptacle expecting to be cooled by air condition. That didn’t happen! We can hear the fan and compressor trying to turn on with a faint hum. My gut tells me there’s not enough juice flowing to kick on the compressor.

No tripped breakers. When we turned the air condition on, the lights on other circuits would get dim- almost like they were competing for the power- but they are on different circuits. I check voltage and got 120v readings from outlets, and the 30A pedestal.

The CG pedestal receptacle looks dirty, and I noticed my shore power plug has some corrosion on the bottom right prong. Could this be what’s causing the lack of power- given that the alternating current wouldn’t be firing rapidly and consistently across all circuits?

My plan is to get a dogbone connection to get the 30a shore power cord into the 50A pedestal receptacle. OR- get a new 30a shore power cord altogether and/or pair it with the dogbone.

Any other remedies I should try or any explanation based on previous experiences?

When you say you have a CG lease and the Airstream is staying there, do you mean permanently or seasonally?

I ask because a 12V system is required to transport the trailer over the road, to power the e/h brakes in the event of a break-away. You should not transport the trailer over the road without this system operational.

[briarbuck00]

Trailer lights are separately attached and are not the concern

[BikeCamper]

Originally Posted by briarbuck00

Trailer lights are separately attached and are not the concern

Trailer lights would be powered by the tow vehicle while connected, so you’re correct that’s not the concern.

I was asking about the brakes. The emergency break-away braking system normally uses the trailer’s 12V battery system as its power source. What have you done to provide power for this system since you eliminated the trailer’s 12V battery system?

[jeffb831]

Besides the brakes, which are separate from the trailer lights, there are some things in the trailer that rely on 12V power to work properly - gas furnaces, hot water heaters, radios, some TV's, etc... Have you made accommodations for all these things?

[ITSNO60]

Originally Posted by jeffb831

Besides the brakes, which are separate from the trailer lights, there are some things in the trailer that rely on 12V power to work properly - gas furnaces, hot water heaters, radios, some TV's, etc... Have you made accommodations for all these things?

In the original post it states that everything has been converted to 120 volts only. briarbuck00 is this to include the lighting and 12 volt controls, in other words you have no 12 volt converter/charger anymore?

[Bill M.]

Yes, you need a way to check the voltage when the AC is trying to start. The fact that the lights go dim is probably a good indicator. A portable or built in surge protector/EMS would tell you what is going on. I have stayed in campgrounds that did not have enough power to the 30 amp outlet. The idea to try it on the 50 is a good idea, I think. I have a permanent site in Florida. In 15 years they have had to replace the 30 amp outlet on the pedestal twice. Both times the campground personnel argued that it was not bad and did not need changing. Both times it completely fixed the problems I was having. Once was certime tainly my fault. I let the plug get dirty enough to burn up. Maybe the other was because of that also.

[uncle_bob]

Hi

Ok, we have split of into two pretty important directions:

120V stuff first:

The 30A input *must* have a high resistance issue. The lights dimming is a really good indication that this is the case. If they are LED lights, the voltage may be headed pretty low. As noted above, you need to measure voltages and see what's what. It could be a wiring error ( = wire that's come loose). It could be your 30A cable (connector or wires). It could also be the campground pedestal.

Now the 12V stuff:

Even on much smaller trailers, when you are on the road, there is a "break away" feature. You have a cable and it goes to a switch on the tongue of the trailer. That cable goes through something on the back of the TV.

When the hitch fails (yes this does happen) your trailer just might start driving itself down the road. There are a lot of videos on YouTube showing this happening. The idea is that the cable will activate the switch on the tongue of the trailer if this happens.

When the switch gets activated it connects the trailer brakes to the 12V battery that is onboard the trailer. That battery then applies the brakes and slows down the trailer. It may not "save" the trailer. It could easily prevent a more serious accident.

This setup is required by federal and state laws. It needs to be there and be working. If you are on the road without it ... that's not a good thing at all.

Does this mean a giant battery? Nope, you can get the job done with a fairly small (40AH) sort of battery that is dedicated to the purpose.

Past that, as noted, there are a number of weird things on a stock trailer that run off 12V. The propane detector is one example. They would need to be driven somehow in a 120V only sort of rig.

Fun !!!

Bob

[DaveG]

Judging from the picture of the 30A plug I would guess that is your problem. It will only get worse and do in the pedestal receptacle. Letting the AC run or try to start as you described, and is on low voltage it get done in too. Suggest you get a volt meter and do some checking. If you are measuring below 106 volts it is time to disconnect. If pedestal voltage is much higher than the trailer voltage you have found your problem.

[Rich Jenkins]

Originally Posted by Wanderings

The contacts on your 30A plug are corroded enough to cause excessive resistance to the electrical current flowing to your trailer. If combined with bad connections in the female plug, this would reduce the voltage enough to cause the issues you've noted. The excessive resistance will cause the plug/outlet to overheat and melt down or even start a fire. The circuit breaker will not trip as the current flow will not exceed the capacity of the 30 amp breaker. Find some electrical contact cleaner and clean the contacts on your plug, then ask the park to inspect their outlet as well.


Often these issues with both the plug and the outlet are caused by plugging into a live outlet. You SHOULD ALWAYS turn the breaker OFF before plugging your power cord into the pedestal outlet. Better yet, before plugging in your power cord, first plug in an EMS/Surge Protector, turn on the breaker and let the EMS analyze the power supply. Only when the EMS clears the outlet as being properly wired and grounded, then shut off the breaker again and plug your power cord into the EMS. NOW you can safely turn on the breaker and power up your trailer.


A former park ranger who has replaced many a fried outlet...

Great reminder. I’m an EE, but always appreciate good solid info backed by hard-won experience from other folks. Thanks for posting this.

[Wanderings]

When using a dog bone to adapt your 30A power cord to the 50A outlet, it is important to remember that the 50A breaker is NOT going to protect your power cable or the trailer wiring up line from the 30A breaker onboard your RV. It's possible that a good 30A EMS would provide some protection, but it will likely depend on the make/model of your EMS/surge protector.


Better safe than sorry...

[ITSNO60]

Originally Posted by Wanderings

When using a dog bone to adapt your 30A power cord to the 50A outlet, it is important to remember that the 50A breaker is NOT going to protect your power cable or the trailer wiring up line from the 30A breaker onboard your RV. It's possible that a good 30A EMS would provide some protection, but it will likely depend on the make/model of your EMS/surge protector.


Better safe than sorry...

As a career electrical contractor I do not agree with that. The 50 amp breaker will certainly protect the 30 amp wiring against a short circuit, and the 30 amp breaker in the RV will protect it against overload. This is commonly done on motor circuits, short circuit protection at the source which is often rated much higher than the circuit conductors, and overload protection at the load. A short circuit draws massive current and there will be no difference in a 30 or a 50, either one will trip in a millisecond.

I know there are folks out there who say "something" could happen to the cord causing it to draw more than 30 amps and less than the 50 needed to trip the breaker but no one has ever been able to come up with such a scenario, or what the "something" could be. I've never seen or heard of it happening either. If there was a hazard code would not allow it.

[uncle_bob]

Originally Posted by ITSNO60

As a career electrical contractor I do not agree with that. The 50 amp breaker will certainly protect the 30 amp wiring against a short circuit, and the 30 amp breaker in the RV will protect it against overload. This is commonly done on motor circuits, short circuit protection at the source which is often rated much higher than the circuit conductors, and overload protection at the load. A short circuit draws massive current and there will be no difference in a 30 or a 50, either one will trip in a millisecond.

I know there are folks out there who say "something" could happen to the cord causing it to draw more than 30 amps and less than the 50 needed to trip the breaker but no one has ever been able to come up with such a scenario, or what the "something" could be. I've never seen or heard of it happening either. If there was a hazard code would not allow it.

Hi

Hmmm .... never .... there's a challenge . Let's come up with something silly:

50A to 30A adapter to a 30 A cord.

30A cord to a (probably home made) 4 way adapter / outlet strip.

Plug in the 30A cables from 4 trailers to the 4 way adapter.

Why? Your'e at a rally or some such nonsense.

One *might* observe that running a 50A cable to the 4 way and doing the 30A conversion there pretty much takes care of the problem. That would be cheating. The faulty design is what it is .....

Has this ever been done with a 30A cable? Like you, I very much doubt it. Is this actually the fault of the adapter? Not in any way. It's that adapter that somebody brewed up that's at fault. ( and then used in combination with the adapter).

Back in the real world:

Any time you plug in a lightweight power cord to a wall socket you have the same "issue". That number 20 cord is not going to be happy carrying 15A. There are a lot of home entertainment devices that come with those little cords. They are safe for the same reason, the intended load is smaller than the rating on the wire and it is fused.

Fun

Bob

[Freedom55]

A soft start on your A/C could help.

[Overstreet]

I don't want an answer. This is a rhetorical comment. I just have some suspicions about the things I hear.

I'm surprised you were able to run everything on a 20-amp GFI outlet on the side of your house. Even more surprised it wasn't the typical 15-amp outlet. I used to run on a 20amp from the shop. I could run the AC and lights but nothing else.

My ACs draw 11 to 14 amps when up to speed and running. Either one with lights and TV running would stop the 20 amp GFI. Also given you converted everything you were likely running Refrigerator, lights, TV, AC and maybe the DVD player.

ALL of that if you converted EVERYTHING to 110VAC why do you have a converter to go out. It makes DC.

AND if you could run it all on a dog bone to a 20 amp circuit at home did you plug that dog bone and 30amp cord into the 20 amp plug in the RV outlet box? Was everything off?

Did anything work with things turned off, ie AC, TV etc. ?

[Bill M.]

Not sure he even said he could run everything at once. He just said "everything worked". My trailer stays plugged into a 20 amp GFI circuit in my garage. I can run the AC on it. I pretty much installed it for the trailer and outdoor tools back in the day and it has about 3 feet of wire run and is the only outlet on the circuit.

Would love for the OP to return and tell us what he has found out. I went a long, long time without a EMS so I understand the reluctance to spend for that. But...now that I have one I really like using it. And this is the kind of situation that would make troubleshooting easier. And easier to deal with the campground people if their is a problem with the pedestal.

[DaveG]

Originally Posted by Overstreet

I don't want an answer. This is a rhetorical comment. I just have some suspicions about the things I hear.

I'm surprised you were able to run everything on a 20-amp GFI outlet on the side of your house. Even more surprised it wasn't the typical 15-amp outlet. I used to run on a 20amp from the shop. I could run the AC and lights but nothing else.

My ACs draw 11 to 14 amps when up to speed and running. Either one with lights and TV running would stop the 20 amp GFI. Also given you converted everything you were likely running Refrigerator, lights, TV, AC and maybe the DVD player.

ALL of that if you converted EVERYTHING to 110VAC why do you have a converter to go out. It makes DC.

AND if you could run it all on a dog bone to a 20 amp circuit at home did you plug that dog bone and 30amp cord into the 20 amp plug in the RV outlet box? Was everything off?

Did anything work with things turned off, ie AC, TV etc. ?

-----
Just a reminder - A GFCI outlet does not respond to current overload, only ground fault current. There are a number of things in a circuit to consider when you plug in your trailer or coach to shore power. The one measurement which will give you the most information is voltage at the point of use. If you are tripping a GFCI that is a different situation, you have a fault current. Integrity of connections, size of wire, and distance are factors in maintaining operational voltage. If all things are good and a breaker is tripping you have a current draw (load) greater than the breaker is rated to deliver or a bad breaker.
✌️