Monitor Your RV’s Shore Power Consumption

Ever wonder just how much electricity your RV is consuming when hooked up to shore power? Want to know just how much each of your appliances is drawing without having to move a meter all over your RV to test everything? Sure lots of RV’s show you how many amps they are drawing at any given time but how much does that calculate to in dollars per hour, day or per month? We wondered the same thing but we couldn’t find a reliable or easy way to meter our usage which would allow us to adjust our usage habits to meet our budget. Ah you know what they say, first search the web to see if anyone built it, if not built it yourself and post what you learned on the internet! This complete total solution will run you under $200.00. That may sound like a lot but you can easily recoup that in energy savings with the data this nifty setup will give you, especially in campgrounds that meter their electricity.

Before we get started:

OK folks, we are working with between 20 and 50 amps of power and if you do not have a good working knowledge of residential electrical systems save yourself the trouble and buy the parts, drop them off at your local electrician and pay him for an hour of his time to put this all together. You might spend 80 bucks in labor but you’ll know it’s done right! Since we live in the good ol U.S. of A we have to say that we aren’t responsible for anything that happens as a result of reading this post or attempting anything you read here. Even making a simple extension cord can cause damage if done wrong so let a pro do it if your unsure or don’t want to assume the risk! Any qualified electrician could build this for you in less than an hour. Ug glad thats out of the way, now onto the cool stuff!

How does it work?

At the heart of the system is an off the shelf product called an Efergy Elite. This nifty little gadget (we are not paid to say that and we didn’t get it for free, no sponsors here!) is an energy management system designed for residential homes. The problem is that RV’s have different electrical systems that homes since they use a variety of power sources like generators, house batteries and street power so hooking up the Energy in a traditional fashion isn’t generally as easy as the instructions state.

That’s where this nifty gadget comes in. We don’t sell them, this is a do-it-yourself project but the parts are available on our Amazon store. To start, I thought about adding the Efergy system to the main breaker panel (then it would read even when on battery or generator power) but realized that many RV’er (myself included) either didn’t want to start taking apart their RV and possibly voiding their warranty or they used multiple rigs and wanted something completely portable.

OK so it’s basically a modified extension cable, nothing special there. The orange box you see pictured here houses the Efergy remote power sensors that capture power consumption. At the ends you have a standard 50 amp male & female plug by Camco.  What i like about this design is that the wiring insulation stays in tact and out of harms way. For our project we used 6/3 indoor/outdoor wire which is the same wire used in most coaches up to 45 feet on their main 50amp/30amp power feed. It may be a little overkill for 30amp but overkill is always a good thing when dealing with electricity & electrical resistance. Here is a great article on the basics of RV electrics including a chart for what type of wire is recommended at various lengths. Our Amazon links below sell the wire by the foot.

Lets Get Started!

For the purposes of this article we are building a 8 foot extension cord to house the Efergy sensors. You can make your entergy sensor box/cable much shorter but we found an extra 8 feet can come in awfully handy once in a while when parks put their power posts in funny spots. You know when you need those extra couple feet? This can be the solution in a pinch, even if you don’t need to read the sensors.

Before we get started lets look at the materials and tools you’ll be needing.

Materials List:

• Efergy Elite or similar energy monitoring system
• 6/3 Indoor/Outdoor Electrical Cable
• Camco PowerGrip Male & Female 50amp (or 30amp) Plugs
• Waterproof Housing
• 3/4 inch Rubber Grommets (2)
• Silicone

Tools List:

• Screwdriver
• Drill with stepper bit (or 7/8 drill bit)
• Basic retractable razor blade
• Electrical Pliers (most any type that can strip and bend wire will do)
• Multimeter (needed if you want to test before plugging into your rig)

Building Your Cable: 

1. Drill two holes in your outer housing at opposite sides. Make the holes approx. 7/8 in diameter so your rubber grommets can fit in the holes securely. (see picture below)
2. Install your rubber grommets in the holes you just drilled, these will keep things dry in bad weather. We used metal electrical grommets for our original box shown in the pictures, but we recommend rubber ones for a better seal and more flexibility.
3. Cut your 6/3 electrical wire to the desired length of the overall cable. We found you can go at short as 2 feet or as long as you like (under 50 feet to ensure the wire doesn’t build up too much resistance for the gauge)
4. At one end, measure 18″ from the end and carefully cut only the outer black insulation around the cable circumference. The wire we recommend has a thin but ridged outer insulation that cuts easily with a razor blade and pulls away without issue. Pull the outer insulation off exposing the inner 4 wires (don’t throw the outer insulation out, you’ll be reusing it in step 8!).
5. Now you should have approximately 18 inches of wire where the Red, Black, White & Ground wires are exposed. There may also be some brown paper which you can cut away as it will just get in the way.
6. Feed all 4 wires through your rubber grommets into and then back out of the sensor box as showing in the diagram below. Feed the exposed wires from the bottom of the box through to the top of the box so that the outer black insulation goes through the grommets but the inner Red/Black/White/Ground wires are exposed inside the box.
7. Attach your Efergy sensors around the black and red wires (hot wires). You do not cut the insulation, the sensors read power usage through the insulation. We recommend you do this step early as the sensors are very hard to install once you finish your cable as the gauge of cable is very tough to bend, especially in that small box! You can leave the sensor’s white wires hanging for now as shown in the diagram below.
8. Now its time to cover up those exposed wires that are coming out of the top of your sensor box. Grab that outer insulation you pulled away during step 4 and cut it to length so that it covers the wires coming out of the top of your sensor box. Slip it over the exposed wire and back down towards the sensor box. When done you should be leaving only 4″ of wire exposed and the black outer insulation should be covering the wires up to your rubber grommets at both ends. 
9. Now its time to install your 50amp (or 30) male and female ends. Your male end will be installed at the top (shorter) end of your cable, and the female will be installed at the bottom. This ensures your sensor box will hang off the ground and away from dirt and debris when its hanging from the power post.
10. Follow the color scheme shown and be sure to tighten everything with your screw driver. For our cable we followed the following standard for 50amp service. Black (110 A), Red (110 B), White (Neutral), bare copper (ground).  Take extra care to ensure no wires are touching each inside the Camco male/female plugs and be sure your male & female ends are identical at each end. If they are touching anywhere or you’ve mixed up a wire you’ll be popping breakers trying to isolate the short later so take your time!
11. Once you have your ends installed, you now have a functioning extension cable with Efergy sensors installed midway down your wire. Congratulations!!
12. Take care to install your Efergy wireless sensor into the box, attach the 3.5mm ends from the sensors into the transmitter, install batteries in the transmitter and arange everything nicely in the box so that it closes without pressing the button on the front of the transmitter. Close everything up and your almost there.
13. Now its time to use that silicone listed in the materials list. Apply a liberal amount of it around the rubber grommets entering your sensor box. This will ensure you keep that water out to avoid damaging your sensors.
14. Thats it, you did it!

Additional Photos:

50 Amp Female 50 Amp Female Closed 50 Amp Male Open/Detailed 50 Amp Male Closed

Testing Cable:

While circuit breakers exist for a reason, they may pop too late or not at all (in very rare cases) causing damage to your rig. Before you use your cable we recommend using a multimeter to test your cable. Here is a link on testing extension cables that will come in handy if you’ve never done this before.

Using your Energy Monitor:

Now that your cable is ready and tested, its time to install it. Its just like any other extension cord, so start by plugging the male end into the power post (breakers off) and the female end into your RV’s main power feed. Then you can flip the main breaker and your up and running! Your Efergy sensors come pre-paired so they should start picking up immediately but if they don’t follow the instructions provided by the Efergy. We found their support to be great but we didn’t need it much because everything worked well out of the box.

Have ideas on how to improve the design or thinking of taking on this project? Make sure to mention it below!

Your comments keep us going and we love hearing from you!

Erik