I have been looking closely into RV wiring and am amazed at the upgrades some people are installing. They are good examples of how buildings could be wired and are another opportunity for electrical contractors to expand their businesses. Safe wiring practices are very important in an RV that delivers 400A of DC power to its systems. Of course, electrical contractors will need estimators to provide pricing for these systems.
Upgrades mentioned here have been successfully installed in RVs I have reviewed. The systems are rarely factory-installed. Traditional RV installers are quoting wait times of three months or more to do these installations.
Let’s break this down into two categories. The first one is power. The RV we are discussing has a 50A two-pole power panel. In an RV, the power from a pedestal is split into two 50A, 120V circuit breaker bus bars. This gives the RV 100A of 120V power. Let’s say it came from the factory with two air conditioners and wiring for a third. Our goal is to add the third air conditioner and be able to power all three without plugging into shore power at an RV park. We also want to add a generator. Our RV already has a residential refrigerator, a convection/microwave oven and other miscellaneous loads such as electric heaters and a coffee maker.
In addition to adding a third air conditioner, we will want to upgrade the existing units. AC starting surge is a problem. With modern air conditioners, you can only run one on a 30A service and two on a 50A service. The air conditioners can be upgraded with soft starters specifically made to lower the starting surge of RV air conditioners. With soft starters installed, you can run two air conditioning units on a 30A service and three on a 50A service.
On the DC side, we will be adding 10 solar panels on the roof and 10 high-capacity lithium batteries for storing power. Making all the components work together is the complex part. These components include solar controllers, transfer switches, inverters and power monitoring equipment. The DC controllers need to know when to send solar power to the batteries or inverters. The controllers also need to be able to start the generator if the batteries and solar are insufficient. The power management system will be monitoring shore power for surges, low and high voltage. Some systems can raise low voltage from shore power by drawing current from the batteries. This solves a significant problem with RV park power during the summer.
The second category is low-voltage work. Our upgraded RV will have full-time internet access, Wi-Fi and cellular boosters, satellite TV and security systems. Many people work in their RVs part- or full-time and need to be in communication with the world from wherever they are. Owners would like to be notified of any problems at the RV when they are away. Therefore, these systems must be able to send notifications to cellphones if there are any problems such as power failure, fire or a break-in. These installations differ from their stationary cousins, and there are manufacturers specializing in hardware for mobile systems.
Relationship-building is very important to contractors getting into RV work. You cannot run to the wholesale house for these systems. Most of them are sold directly by manufacturers to end-users. Relationship discounts are available, and you will need to work with a range of manufacturers for the various system components you will be installing.
While the installations are similar to those made in a building, there are extra difficulties when working on RVs. Since storage space is often limited, finding space for the installations can be tricky. Also, running the wiring is a challenge, as many RVs have completely sealed underbellies. Working in the underbelly requires careful removal of the sealing material and insulation, which must be restored to its original condition to maintain protection from freezing.
Codes and standards
Finally, I want to mention installation standards. The National Electrical Code is not enforced for RV installations. However, the National Fire Protection Association created a code book specifically for RVs: NFPA 1192. The Recreational Vehicle Industry Association (RVIA), Reston, Va., requires that all manufacturers displaying the RVIA tag comply with NFPA 1192.
RV installations can be a good niche for electrical contractors. Food for thought: RV sales reached an all-time high in 2021. In 2022, a projected 600,000 units are expected to be sold.
Note: Read “Hitch Your Wagon” from the June 2020 issue of ELECTRICAL CONTRACTOR for more about contractors and RVs.
About The Author
CARR has been in the electrical construction business since 1971. He started Carr Consulting Services—which provides electrical estimating and educational services—in 1994. Contact him at 805.523.1575 or [email protected], and read his blog at electricalestimator.wordpress.com.