DISCLAIMER: AS AN AMAZON ASSOCIATE I EARN FROM QUALIFYING PURCHASES. THIS POST CONTAINS AFFILIATE LINKS THAT WILL REWARD ME MONETARILY OR OTHERWISE WHEN YOU USE THEM TO MAKE QUALIFYING PURCHASES. FOR MORE INFORMATION, PLEASE READ MY EARNINGS DISCLAIMER.
Plugging your 30-amp service into a 50-amp outlet is possible if you use an adaptor and a surge protector. The adaptor (also called dogbone) will convert your 30-amp plug into a 50 amp plug and a surge protector will keep your appliances from getting fried if something fails.
The problem is that if you plug in your 30-amp adaptor into the 50 amp breaker, it will only trip if the current exceeds 50 amps. The wiring that leads to the main panel is only rated for 30 amps, so if there is a short (and excess current starts going through), it may not be able to handle it!
Using a 30 amp adaptor with a 50-amp breaker is not just dangerous, but it is also a violation of the electrical code. However, if 50-to-30-amp RV adapters were a safety hazard, National Electric Code would probably not allow them to be sold to the general public.
When plugging 30-amp into 50-amp service, check carefully your wiring condition as well. If the wire has worn places from all that moving around in your trailer, that could produce a short. In this situation, if something is wrong with your breaker, all this power will go right through your RV’s 30-amp wiring!
Making sure your wires are always in a good condition will help you avoid any problems like these in the future.
It would be wonderful if these dogbones had a 30-amp fuse built-in, but unfortunately, they don’t.
Many campers with 30-amp service prefer to use 50-amp connections because they have a larger contact surface area. Sometimes you don’t even have a choice if your park offers only 50-amp outlets… If you don’t an adaptor handy, you can always ask a manager of your campground to see if they can rent you one.
50-amp receptacles have the advantage of being less frequently used and hence in better condition. As long as you connect your RV using an appropriate 30-amp rated supply cord you should be fine using a dogbone adaptor, but there are some ways (mentioned below) to make sure you are protected in case something wrong really happens to you.
Here is a good video on that:
Surge protector to the rescue!
Using a surge protector with an overcurrent shut-off feature is the easiest way to protect your vehicle in case of a short. All you have to do is:
- Step 1. Connect your 30-amp plug into a surge protector
- Step 2. Connect surge protector to a dogbone adapter
- Step 3. Connect dogbone adapter to an outlet at the pedestal
It’s a good idea to check your pedestal power with a SURGE PROTECTOR or multimeter (or voltmeter), to make sure that it is wired properly and has enough power BEFORE you plug in your RV! If you are not getting enough volts (usually below 108-volts) it can seriously damage your electronics.
This is especially true for the summer season where most people would like to use their A/C. With a digital voltmeter (paid link), you will be able to check different outlets to find out which one of them has the highest voltage and use it.
Another neat tool you may want to have in your toolbox is an Autoformer, which can boost voltage when needed. Here is an Autoformer for 30-amp service (paid link) that you can conveniently get from Amazon:
It is fully automatic and will alert you of boosing with indicator light. And it actually has a surge protector built-in…
You could be in a situation with an RV park offering a reverse polarity 30-amp socket or faulty 30-amp breakers that do not stay engaged and having a 50-amp to 30-amp dogbone adaptor, could just “save the day”! This is another reason why a good surge protector can come in handy.
Here is a good 30-amp surge protector from WatchDog (paid link) with a power shut-off feature:
Overcurrent protection and auto-off are NOT available on all surge protectors, so make sure you read specifications carefully before buying one. You need the power to be DISCONNECTED in overload situations, not just limiting various spikes here and there.
Even though good surge protectors are pricey, they can also offer you valuable information about your power connection:
This information gets displayed on your mobile device and you can keep on checking it as much as you need. Another way to limit your current amount (in case it gets out of hand) is to use an inverter.
You can also use inverter-charger
You can install an inverter charger that can be programmed to limit the power that your 30-amp RV service will be getting. The cool thing about this unit is that it works in the other direction also! If you are not getting enough power, it will use batteries to make up for any power loss.
These inverter-chargers could be pricey but maybe a worthwhile investment in your situation:
You will always have a stable 30-amp current, regardless of whether you are getting too much energy or too little of it.
This device will also charge your batteries and in this setup up the power transition will be so smooth, that you will never really know what is happening to your main power supply!
Here is the most popular inverter-charger for RVers from Victron (paid link). It can be programmed to whatever power you need and it will replace a converter as well:
Even though the inverter-charger in your RV will act as an extra layer of protection for your appliances and electronics, I still recommend you to use a surge protector in this arrangement to protect your 30-amp cable (which is the only piece of the circuit that isn’t properly protected).
Should you just rely on a breaker?
A 30-amp breaker in your RV will safeguard against some overloads, but if left unattended for a long period of time, your cord and connector could get destroyed. Your amperage draw depends on what you turn on at that moment.
If you accidentally overloaded the circuit with appliances that take too much power, the camper’s breakers will always protect the internal wiring. But what is going to protect external wiring?
When you plug your 30-amp RV service into the 50-amp receptacle, you need to make sure that:
You do NOT try to draw more than 30-amps (or 3600 watts of power all at once).
It may be tempting since the 50-amp receptacle on the pedestal has more capacity, but you don’t want to take your chances and heat things up before they get out of hand and start triggering breakers.
Of course, your 30-amp coach breakers will provide some protection, any breaker that is frequently tripped degrades to the point of needing to be replaced. Imagine you have a BAD BREAKER and don’t know anything about it!
When should you use the adaptor?
- There are cases where only 50-amp connections are available in the campground. It’s unusual, but it does happen.
- The 30-amp receptacle at the campground could be in a bad shape. Since most RVs are 30-amp, they will be the most used. The outlet can be worn out so much, that it is capable to overheat and damage to your plug. Sometimes, you can request that the connector be replaced at the campground, but it’s not always easy.
- When the campsite wiring system is overloaded and everyone is trying to use their A/C, one leg or 50-amp service (that adaptor will use) may deliver greater and more stable voltage.
- The 30-amp cables in many parks were placed years ago and may be made of aluminum. 50-amp outlets are newer and made out of copper.
Is this adaptor safe?
The main argument to whether or not to use this type of adaptor is if the cord will melt in the event of a short. Some people say that:
In the event of short the cord will overheat, melt and catch fire BEFORE 50-amp breaker trips.
Others say that:
The breaker WILL TRIP normally due to really high current and you will have no problem.
People claim that 100 and even 1000 amps will flow through the wire when short is created, therefore a 50-amp breaker will quickly trip and cut the electrical power supply. Here is some more technical information on shorts (external link), if anyone is interested.
How electrical circuits get overloaded, here is a good explanation:
So, can we use 50-amp to 30-amp RV adapter (paid link) to make our lives a little bit easier?
It is probably true that you will be fine with just using an adaptor, but protecting weaker wires with a surge protector that acts like a fuse, does seem logical and electricity is NOT something you want to “play” with!
Why? Because sometimes it seems to have a mind of its own…
It is also a good idea to have 30-amp to 15-amp (or 20-amp adaptors) on hand at all times, which will allow you to charge your batteries or use a fridge when you are parked in the friend’s driveway, (for example). Just plug it into their garage’s 120-volt outlet and you can sleep in your own bed!
A 30-amp to 15-amp adaptor allows you to plug in at home, but you won’t be able to run much beyond the fridge and converter until the batteries are fully charged. This is usually good enough for travel prep and getting ready to go.
I recommend that all RVers carry a full set of adaptors so that they may plug into almost anything (EXCEPT for the 30-amp outlet that is actually 220 volts!)
As you see, it is perfectly safe to plug your 30-amp rig into a 50-amp outlet service and all you need is just a way to protect your appliances and wires. Even though a real short will probably trip the 50 amp breaker, it is still better to protect your hard-earned investment in the ways mentioned above.
In a nutshell, you never know when you’ll need protection… but when you do, you’ll be glad you have it.
This article is for informational purposes ONLY and is NOT a replacement for professional advice!