Connecting external power to a complex Motor Coach, Class A or Fifth Wheel camper at a campground can be tricky. Mistakes can be costly and ruin a camping trip before it even gets started. We have spent years researching products for our new coach. We don't make those costly mistakes ourselves!
This is our first article in the series that will walk though the process of properly connecting a Modern Coach to external systems. This article is focused on covering everything from A to Z related to Electrical Power connectivity and systems. After reading this article you will have the answers to the most common questions we have encountered:
- How are campgrounds wired?
- What Parts do I need to connect a 50A motor coach?
- Do I need a surge suppressor?
- What is an Autoformer?
- How do I connect a 50A camper to a 30A service?
- How do all of the parts plug together?
- What is a Dogbone?
- Can I Moochdock with my 50A Coach?
The first step in the setup process for us is connecting power to the rig. This step is often glossed over, but it is one of the most important steps when setting up a rig. Power surges, shorts, connecting to bad power, etc. can destroy sensitive electronics in an RV. Field servicing electronics is extremely difficult. Very few RV techs have the tools or expertise to troubleshoot complex electrical systems.
It is crucial that anyone connecting a camper to external power of any type knows exactly what they are doing and why they are doing it. Mistakes can be deadly.
Why is Power a Problem in a Campground?
RV Park Infrastructure
Campgrounds across the country are aging. Not many new ones are being built. It is common to encounter a campground that was originally built for lower powered rigs and later retrofitted to accommodate 50A coaches.
It is expensive and time-consuming to change wiring, power pedestals, grid connections, etc. The end result is park owners are motivated to keep construction and capital investment to a minimum. This is especially true when the changes they are making are not a profit center.
RV Parks are not in the business of running a power company. Providing 50A service is a necessary amenity, but it is not a core service such as a pool, clubhouse or restaurant that attracts new customers. This is a key reason why it is common to see AC voltage fluctuations, brown-outs, blackouts and short circuits at a RV Park when we we rarely see these types of issues in a residential area.
RV Park Challenges
Air Conditioners, Refrigerators, Air Compressors, Washers, Dryers and other devices with motors not only pull high amps, every time they cycle on and off a surge is generated on the power grid. Air Conditioners, for example, turn a compressor on and off hundreds of times during a day. When the low temp setting is reached the thermostat tells the compressor to shut down and stop cooling. When the coach warms up the thermostat tells the compressor to start again. On a hot day AC units are all cycling constantly.
Air Conditioner cycling is the leading cause of problems with campground electrical infrastructure. The on/off compressor cycling causes surges that drop voltage on the line. Low voltage makes motors work harder resulting in early failure of the component.
Motorhome & RV Wiring
The 50A service that most larger RV's have is actually comprised of 2 50A feeds (2 phases) routing into a coach through a single power cable (combined 100A service). The two feeds are commonly referred to as Legs. Leg 1 is the primary feed and Leg 2 is the secondary feed.
Most motorhomes and RV's are wired to favor Leg 1. RV Manufacturers typically configure all of the primary components on Leg 1 so when a rig is partially connected to power (e.g 30A service or inverter) the essential systems such as the refrigerator continue to operate while the other leg would be inoperative.
The challenge with RV parks is that Leg 1 tends to get most of the abuse. Leg 1 of the gird is what powers the 30A rigs as well. AC's cycling on and off on Leg 1 will cause that leg to have more voltage surges than leg 2. What this means in English is half of the coach can have more voltage fluctuations than the other half, which can cause a variety of unpredictable issues with sensitive electronics.
NOTE: a properly wired campground will evenly distribute their power legs between campsites. The idea being that every other site would primarily favor leg 1 or leg 2. The reality, however, is that it is much more expensive and complicated to wire a large campground by the book. Regulations for RV parks are different than residential neighborhoods as well. There is more leeway to cut corners…and they do!
Uneven leg voltages is virtually unheard-of in a traditional home environment, but it is very common in RV parks. We install these cheap voltages monitors in our rig. We have one on one leg and one on the other. It is common to see them reading different voltages.
The challenge is that it is not easy to see a problem in the coach without some sort of monitor. Most of the time everything appears to work normally. The first sign of problems is when circuit boards burn-out, AC compressors die, computer power supplies stop working, etc. out of the blue. One day the Microwave is working and the next day it isn't. Most chalk this up to a bad component because everything else in the coach may appear fine, but chances are when something randomly fails the likely root cause is power.
Common Solutions to Protect the Coach
The vast majority of RV's have a surge suppressor of some sort installed on board or as an add-on device at the power pole. They are one of the most common essential items that are added by owners. Although we strongly believe every coach needs a surge suppressor, we believe they tend to create a false sense of security. Surge suppressors protect from “Power Surges” and spikes, not brown-outs and low voltages.
High-voltage spikes are generally act of God events such as a lightning strike. Even indirect lightning strikes can cause a power surge on a campground power grid. The static electrical charge created by a strike will jump into any conductive material like power lines and cause a power spike on the grid. Most surge suppressors are specifically designed for this condition. If high voltage is detected they short it to ground, which redirects the power away from the coach.
Outside of being in a thunderstorm, however, high-voltage power surges are not as common as most think. Power grids are designed with transformers that step down high-voltages coming in from main transmission lines to usable power. Although transformers do fail, when they do they are designed to internally short and kill power output to the grid without a surge.
An electrician or power worker connecting high-voltage lines to the low-voltage output would definitely cause a power spike, but this is a rare occurrence because crossing high-voltage lines with low-voltage could kill them.
There are certainly other events that can cause a power spike. A car can hit a transformer shorting it out, a tree can fall on a main power line, etc., but again these types of issues statistically are not what causes most problems for a camper.
Brownouts the Silent Electronic Killer!
The most common power issue for a coach are caused by brownouts (e.g. low voltages), not high-voltage spikes. Most surge suppressors do NOT monitor voltage or amperage. They are useless for protecting from conditions that can cause thousands of dollars in damage to sensitive electrical components and motors.
The first line of defense for brownouts is to have an intelligent power monitor that looks at both power legs independently in addition to protecting form power surges. The list of devices that can do this effectively is a short one. There are three market leaders in this space.
Next we will discuss how to protect the coach from the problems that are common in campgrounds.
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Surge and Brownout Protection Systems
Progressive Industries have been around forever. They are the original company that identified the issues with campground power and created an entire line of products that are designed to protect our beloved campers. Most of their products, however, only cover surge protection.
Progressive sells a few products that will monitor the electrical power. They call their power monitoring technology EMS (Electrical Management System). The Progressive Industries EMS-PT50X is their portable 50A unit that plugs between the power pole and electrical cable that leads to the coach. The EMS-HW50C is the hardwired version.
The image above shows how Progressive Industries breaks down their products. The EMS devices are the only ones that should be used in a camper for full protection. The challenge with Progressive, however, is they have not updated their products in years. They only protect up to 3,500 joules power surge and the electrics are not as fast as newer products. They are also considered disposable devices. When they protect form a power surge the device is destroyed and must be replaced.
Southwire Surge Guard
The device that has moved into pole position regarding power protection for coaches is the Southwire Surge Guard. Like Progressive Industries, they sell a wide range of devices, but only two of them fully protect the coach electoral system. The Southwire Surge Guard 34951 is their portable 50A system that plugs into the power pole and cable leading to the Coach. The Southwire Surge Guard 35550 is their Hardwired 50A system.
The Soutwire product line is solid. They also offer a bluetooth add-on that will enable monitoring from a smartphone that is handy. Like the Progressive product line, the Southwire devices are not field serviceable. If they fail due to a lightning strike they cannot be repaired in the field. The failures are also a bit more likely than Progressive. Sourthwire surge suppression only covers up to 3,350 joules — progressive is 3,500 joules. A surge that exceeds this capacity will render the Southwire devices unusable. A coach will be completely unprotected until the repaired unit is received.
Hughes Power Watchdog
The new kid on the block in the camper power protection space is the Hughes Power Watchdog. Like the others, Hughes has a line of products that cover surge only to full electrical system protection. The Hughes power protection technology is called Emergency Power Off (EPO).
The Hughes product that fits into the power protection category similar to Progressive and Southwire is the EPO Power Watchdog. Hughes sells a 50A portable Power Watchdog PWD50-EPO and a Hardwired Hughes 50A Power Watchdog PWD50-EPO-H.
Hughes had the benefit of entering the market later than the others. They were able to engineer their products to outperform the competition in several key areas.
- A key differentiator between Hughes and their competition is their surge protection rating. They will protect a coach up to a 4,800 joule power surge, which is 1,000 joules more than their competitors. The higher surge protection could make the difference between a completely dead unit to one that continues to operate.
- The second area that differentiates the Watchdog from everyone else in the space is they are field serviceable. Hughes sells a Replacement Surge Module for PWD50-EPO for $32. If it fails due to a surge a Phillips screwdriver is all that is needed to replace the surge module and get the unit operating again.
The Hughes Watchdog comes standard with Bluetooth and their app that is available for Android and iOS is excellent. It provides complete monitoring of power that includes a power meter that tracks precisely how much power has been used. This is a useful tool when staying at parks that charge for power usage or when wanting to calculate how much power you are using to build a properly sized solar system.
After reviewing the market, we decided to go with the Watchdog in our Coach. We have a hybrid setup where we install portable devices in the coach vs hardwiring it into the system directly. Out setup keeps the expensive devices from hanging on the pole and enables us to easily remove it form the line in case we have problems. We will post another article that shows more details on how we have our system configured. Stay tuned…
Brownout and Low Voltage Active Protection System
Up until this point we have been discussing systems that protect the coach by killing power going into it. A good power shutoff system will certainly protect the coach, but they do not do anything to fix the power. All they do is turn the power off if there is a problem and turn it back on when the problem is gone.
The Hughes Autoformer is the only device we are aware of that actively corrects power problems. An Autoformer interacts with the power grid and helps resolve or absorb issues through internal transformers before the problem gets to the coach.
Common problems like a leg voltage low like we discussed above is mitigated with an Autformer. The device monitors incoming voltage on both power legs independently. If it sees low voltage on one side it automatically routes the power through step-up transformers that will level out the voltage on both legs. The transformers also filter and clean the power before it gets to the coach.
Autoformer's “Transform” incoming power to a cleaner power on the coach side. The transformation and step-up process takes power that would be unusable and transforms it to something stable and useable. The Hughes system also has a fail-safe mode. If it cannot clean the power to a safe-useable level it will shut the power going to the coach immediately. It will reactivate the power when it is acceptable automatically as well.
Another benefit of the Hughes Autoformer is that it has the same field-serviceable 4,800 joule surge suppressor that also protects form lightning. A screwdriver and a spare replacement module is all that is needed to get a unit that was hit by lightning operating again.
The next topic we will discuss how we get power from the campground into the coach.
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50A Electrical System Connections
Now that we have covered the systems to protect the coach from bad power, we need to actually connect the power from the park power pedestal to the coach.
We have looked at a ton of power cables over the years. Most connect straight into the power plug on the side of a camper and hang down. The problem with the normal cables we see everywhere is they put a ton of stress on the side of the camper and connector.
The weight of a standard power cord hanging down constantly pulls against the connector. If the connector fails the coach is dead. We are not sure why nearly every power cable has a straight connector, but the vast majority of cables on the market have the straight female connector.
After researching every cable we could find, we found the Marinco 30RPC50RV. This is a heavy duty cable that has a 90 degree angle built in. We also like the yellow color. It makes it easy to see when walking around the rig.
If you already have a power cable with a straight connection, there is an easy fix for this. Camco sells a high quality 90 Degree 50A cable adapter. The 90 Degree end connects to the Coach. The other end connects to the power cable. The 90 Degree angle takes the leverage off of the power socket and transfers the load straight down.
50 Amp Power Extension Cable
The power plug on our Momentum 397TH is mounted in the front next to the the service-side water bay door. Most parks have the power pole at the back of the lot. When rigs are set up like ours, it is common to find a power pole that is more than 30 feet away from the main connector. When encountering this situation power cannot be connected to the coach unless we have a 50A extension cable with us.
The problem with most of the extension cables on the market is they are made with small gauge wires that cannot deliver the full 100 amps (50A x 2) over 60 feet. They minimally build the cable to handle 100A for 30 feet, but not to handle the load through the extension and into the main power cable.
Every wire has resistance. The smaller the wire the more the loss. Devices in a camper are designed to have full amperage available to them at all times. When an AC or high-demand system is running it will pull the amps it needs. The cables will deliver the power until they eventually overhead and fail. Failures can range form not having power to melting the insulation exposing the internal wires that can shock and kit someone. Cable shorts can also damage sensitive electronics. Bottom line is always use high quality cables.
We always have good luck with Camco products. We carry this Camco 30′ Outdoor 50-Amp Extension Cord with us. Most of the time we don't need it, but when we do we are grateful to have it on board. Trying to find an extension cable at a park is not easy. If we need it, chances are other people need them as well. Connecting this power cable to our main cable extends our reach to 60 feet. If that doesn't make it then we change campsites.
The next section we will discuss powering a 50A coach from 30A service and Muchdocking from standard 15A house electrical outlets.
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Alternate Power Sources
Connecting a 50A Camper to 30A service
Campgrounds are aging. State Parks and many of the older campgrounds only have 30 amp power. Most of the campgrounds in Mexico only have 30A power as well. When a 50A coach encounters 30A service, the only way to connect is to have the proper adapters that are safe to use.
As discussed earlier, 50A service is actually 100A. It is two phases of 120 VAC power that combined make 240 VAC. 30A, however, is only one phase that is rated to output a maximum of 30A. Out of the gate the power coming in from a 30A service is 20A less than one leg of the 50A service and 70A less amperage overall.
It is important to keep in mind that although we can get every electrical outlook and device powered in they following configuration, that does not mean everything will work the same as it would at a 50A service.
Direct 30A to 50A Dogbone
The easiest way to get up and running is to have a 30A to 50A adapter. These little cables are often referred to as Dogbones. These are cheap devices that can be easily stored on board. When needed we use the normal 50A cable to get to the power pole. Then plug the male end of the standard 50A cable into the female 50A end of the dogbone. Plug the 30A male end into the power pole's 30A socket and we are connected.
The standard 30A to 50A dogbone takes the single phase from the 30A power pole and connects it to both legs on the 50A end. This configuration provides full AC connectivity to everything in the coach. On the surface everything will look like the coach has full 50A service. The challenge with this configuration, however, is it is very easy to draw more than 30A from the power feed. When this happens the circuit breaker at the power pole will trip shutting off power to the rig.
50A Rig Connected to 2 30A Power Poles
A trick that works well if you are in a location that has 2 30A outlets is to connect two different 30A services to the coach. The first leg will connect to Leg 1 of the 50A service and the second 30A outlet will connect to Leg 2. To accomplish this you need a different 30A to 50A dogbone.
The EPICORD Y adapter has 2 male 30A plugs that connect into a single Female 50A connector. The 50A end connects into the 50A wire running to the coach. The two 30A ends plug into two different 30A receptacles that each have their own 30A circuit breaker.
The challenge with this configuration is most of the time the power poles only have 1 30A plug. The easiest way to resolve this is to have a 30A extension cord that will reach the second pole. If we know we are going to be in a situation like this we will borrow or buy a Camco 50′ 30-Amp Extension Cord to have with us.
The Camco 30A Extension connects to the second 30A end of the dogbone and routes over to a second power pole. The link above is to a 50 foot cable. The longer the better since power poles are often across on the other side of an adjacent campsite.
The advantage of this setup is that you would have 60 amps out of the normal 100A available for use. The coach would not be able to run all 3 AC's, but 2 AC's split across the Legs and reasonable power management is doable.
Moochdocking 15A to 50A
Moochdocking is a term used when a rig is parked at a friend house and “Mooching” off of their power, internet, and water. The challenge in this configuration is that most homes only have 15 amp power outlets and the outlets are often daisy-chained together (all on a circuit combined is 15A max). Obviously this would be a minimal viable configuration to run essential items like a fridge, TV and/or lights, but most of the time you cannot operate an AC or any heavy draw items (e.g. Microwave, Fireplace, Hair Dryer).
The first part of the process is planning. Routing wiring from the camper to a 15A outlet in a house can be tricky. Campers are big. Chances are they will be parked well beyond the reach of the standard 30 ft 50A power cord. If we add the extension we can get to somewhere around 60 feet. If we are lucky this will get to an outlet, but chances are 60 feet isn't sufficient to get us to a useable power outlet either.
We have to get to the outlet somehow and we don't want to carry around several heavy 50A cables for the rare occasion we need to moochdock. We have found the easiest way to make the final extension is to use a standard heavy duty outdoor extension cord that is rated to carry at least 15 amps. The heavier the wire the better. Cheap orange extension cables are often made of lightweight wire. They will overheat and fail. This is the one we use. It is heavy, but it is rated to carry 15A continuously. We have never had this cable overheat.
We carry two of these cables with us. A 50 ft extension and a 100 ft extension. Generally we are within 50 ft of a single outlet, but we may need to run 2x that distance to get to another outlet that is on a different circuit. It is nice to have two different lengths, but realistically we could stick with 2 50 ft cables.
What is needed from here is to connect everything together. Running form the coach use the normal 50A cable. Either the 30 ft standard or combined with the 30 ft extension to get 60 feet.
The next step is to connect the 30A to 50A Y dogbone above to the 50A cable. This will convert down to 2 independent 30A legs.
The final step is to use an adapter that coverts 30A to a standard 15 A plug. The easiest way to do this is to have 2 of these adapters.
The adapter is the final piece to change the gender down to a standard plug that will work with a normal extension cord.
Alternatively, it is possible to go directly from 50A to 15A. They sell adapters that go directly from a 50A cable to a normal 15A plug, but we have found this isn't very usable. 15A running our entire 100A coach isn't sufficient. We end up blowing circuit breakers in the house that are a hassle to keep resetting.
We hope this article helps you safely connect your electrical system to the grid. The key thing to keep in mind is to think before you plug. Diagram out in your mind or on paper what you are trying to accomplish. This is especially critical when you are using doglegs and adapters. It is easy to plug something in incorrectly, which could result in catastrophic damage to your coach.
We have drafted what works for us in this article, but it is ultimately your responsibility to protect your investment and people around you. Do not play with electricity. If you are not comfortable with anything find someone who is. Virtually every campground will have someone in it that knows how electrical components fit together. Campground management or their maintenance workers will certainly know what works at their site. When in doubt ask an expert. Most of the ones we have met will share advice and lend a hand for free.