To carry out on your campervan conversion electrical system.

In this article we will cover some basic tests that you can carry out on your own self built electrical system within your van conversion or tiny build. These very simple tests can be the difference between a safe or dangerous installation. They help to identify loose connections and ensure that you take some time to check over your system upon completion, a stage that many miss.

---

Safe isolation of your campervan’s DC system

For the purpose of this article and the discussion of basic testing, we consider the reader to have a basic understanding of their electrical system and a basic arsenal of tooling and test equipment.

Before you start, it’s always wise to safely isolate the circuit(s) in which you wish to test. To do this you will require a device which can measure voltage, it will need to be capable of measuring direct current (‘DC’). This is the setting you will use to see the voltage in your system.

Firstly, you need to fully isolate your campervan’s DC system via your main isolator. If you do not have a main isolator for your DC system, we highly recommend that one is installed, as should an emergency arise, you need to be able to shut the entire system down quickly and efficiently.

If your system contains solar panels, please use your solar panel isolator to isolate the PV array. If there is sunlight hitting your panels the PV system will produce a voltage and therefore needs to be isolated so that we can test in a safe manner.

Once your main isolator is in the off position you can then perform the basic test of switching on lights and other DC equipment. These should, of course, not turn on.

Just because these devices do not turn on, does not mean your system is safely isolated yet, for this we need to use our test equipment.

You can then take your voltage tester and test across your positive (+) and negative (-) at any point after the main isolator. The reading should be 0v. For the purpose of the installation specified in the photos, we tested from the positive busbar to the negative busbar. Another good place to test for voltage is on any devices that have exposed terminals, such as a solar charge controller (pictured right), here you can test for both your system voltage and your solar panel voltage, because both isolators are in the off position, these should both read 0v. Once you have read 0v from both your system voltage and PV voltage the isolators must remain in the off position. This now gives you a safely isolated DC system which you can test.

---

Visually inspecting your campervan’s electrical installation

A visual inspection of your campervan’s electrical installation is crucial. It is good practice to sit and run your eyes over the system, thinking of the flow of electricity like the flow of water through pipes. Ensuring that all the right cables are making their way correctly from A to B to C to D. This a not only a good way of ensuring that your system is correctly connected but also a good way of understanding your system and how it works.

This is also a great stage of the inspection process to reference your wiring digram (schematic) that you used during the installation process. Follow the diagram like a flow chart and ensure all devices are in the correct sequence and have the correct cables running to and from them.

A visual inspection of your cable management is also a key aspect here. All cables should be secure and protected from external influences. Cable trunking is a good example of cable management. It protects the cable from any external damage from the likes of surf boards and mountain bikes thrown in the back of the campervan at the end of the day.

The trunking also provides the cable with some air flow, enabling the cables to dissipate any heat effectively and operate at their designed specification.

Visually inspecting how your cables enter enclosures such as control panels and jointing boxes is also another key way of ensuring system longevity. Cables entering via sharp edges can cause potential damage to the cable over time. Here we must ensure that the cables are protected whilst the vehicle is moving and vibrating. Over time the sharp enclosure edge could slice into your cables and cause substantial issues, so you can make a quick wiggle check, ensuring the gland or grommet is holding our cable firm and protecting it as it enters the enclosure.

---

Tug testing your campervan’s electrical system

If the cable pulls out during a tug test then it was never going to stand the test of time.

Tug testing is an extremely basic electrical test but a critical one. Too many people forgo this step and issues that later on arise could have been solved by simply tugging on a cable to reveal a loose connection. 
Tug every single termination that you have made, yes every single one, there are probably hundreds, but do this! 
For terminations using lugs, these have more than likely been fixed using a nut and bolt method, a wiggle of the lug will suffice.

Checking that the lug is secure, creating a good, solid face to face connection and also that the copper within the lug is crimped tightly and that no strands of copper protrude the lug from the side in which the cable enters.

Key areas for tug and wiggle testing are at the fuses and protection devices. A loose connection here can cause a high resistant joint, the high resistance joint will ultimately result in a higher current being pulled though the loose joint and this could result in arcing, which can potentially lead to a fire.

If you have used through crimps, boot lace ferrels or, the ever popular, WAGOs in your installation then these can also be tug tested. Remember if the cable pulls out during a tug test then it was never going to stand the test of time. When you start taking your campervan down those bumpy lanes to get to the best surf location these connections need to be solid. Finding these loose connections is what tug testing is all about, you would rather find it now at this point than when your miles from home enjoying your travels.

---

Identification of cables within your campervan’s electrical system

Identifying your cables is a really good way of future proofing your installation.

Buy a labeller and label everything! You’ll be on your travels, an issue will arise and the labelling process that you undertook will save you hours.

Labelling all your DC circuits is the key to identifying which cable is supplying which piece of equipment in your tiny build.

You should also label every isolator. Knowing which isolator you’re turning is crucial. If your van sits for a period of time you may want to isolate certain aspects of the installation. This is a great way of knowing exactly what is isolated and what is not.

Labelling your individual fuses is also a must, this can save a whole lot of time fault finding another day. Knowing what part of the system has failed and then knowing where said components are is crucial to any installation.
Ensure your cable colours are correct. This is crucial in any good installation. Using a red colour for your DC positive and black for your DC negative is a good place to start. If you have a plain black cables, such as cables coming from your solar panels, its always a good idea to label your positive and put a little red band or heat shrink around the neck of the cable.

---

Basic continuity testing of your campervan’s electrical system

Once you are satisfied with your visual and tug testing you can then move onto some basic continuity testing.

Continuity testing is simply ensuring that the start of your cable is connected to the end of your cable.

As an example, you will have a cable that is connected at your battery or busbar (origin), and will run to your 12V DC distribution panel (load), to power your lights, fridge and fan.

Now, that cable should be continuous, from the origin to a fuse and then from the fuse to an isolator and from the isolator to your distribution panel.

Sounds obvious when said, but by the time you get to the end of your build these cables will be covered by your cable management, buried in walls and hidden behind kitchen cabinets and shower rooms so they can no longer be seen in their entirety.

Once your test equipment is on the continuity setting (see pictures below) you can simply touch the ends of the probes together and you should either hear a beep, get 0.00ohms or sometimes both (diagram above left). You are simply creating a loop. Your meter is sending out a signal on one probe, it touches the other probe and returns said signal to the test equipment.

Remember: Lower number = Lower resistance & Higher number = Higher resistance

You are doing exactly that, but the probes will be at each end of your cable. Your cable becomes part of the loop, this is how you test for continuity, you are ensuring your cable is continuous and has no breaks.

At this basic level of testing you are simply listening out for a beep or looking for a low value. Just bear in mind that values will vary due to the differences in the length of cable, fuses, switches and thickness of the cable.

Every joint that you make adds a level of resistance the the circuit. That is what you are measuring with your test equipment. A thick piece of cable with no joints will produce the lowest reading whilst a thin piece of cable with plenty of joints, fuses and switches will create a higher reading as there are more obstacles in the way, that is what we call resistance.

You can run through a scenario with the diagram below.

You first, touch one of the probes (it doesn’t matter which) on to the positive busbar(1), (if your system doesn’t have a busbar, the nearest positive terminal to the dead side of the isolator will suffice).

Once the probe is firmly on the positive busbar, you can then put the other probe onto the next connection in the diagram, which is at one end of the fuse(2). Here, if the cable is uninterrupted and continuous you should hear beep from your multimeter and, or a low reading.

You now know the cable between the busbar and the fuse is continuous.

You can then move to the fuse itself, put the first probe on one side of the fuse(2) and the second probe on the other side of the fuse(3), beep/low reading! This confirms to you that your fuse is intact and has not been broken or has blown.

Next you take a probe, put it on the outgoing side of the fuse(3) and connect the second probe to the positive connection on the lamp(4), beep/low reading!

You have confirmed that from the busbar, the origin of the circuit, you have continuity to the load, the end of our circuit and therefore the electricity can freely flow along this route without any issues.

*Note, your test leads may not be long enough to reach end to end of every circuit. You can make a longer bit of cable which will help you reach other parts of the installation, this is known in the electrical industry as a wandering lead.

*Not all cables need to be continuity verified, I appreciate this takes time and if you can see the cable in its entirety then you can be 100% sure this cable is entire and connected at both ends.

This is a really good way of proving you have good connections and your circuit is entire. If this is your first installation I recommend doing as many cables as you possibly can. If you are more experienced you can apply diversity factor and do a random selection.

---

Summary

We at Tiny Build Electrics believe the words “electrical testing” can seem daunting. You may think it involves complicated procedures and equipment, and sure, it can do, but, we believe by doing some small, basic tests like the ones that we have discussed here in this article it is certainly better than none at all. If during your testing process you find one slightly loose cable or a mislabelled fuse then it was worth it.

Visually testing, tug testing and carrying out basic levels of continuity testing does not need to be complicated nor scary. By carrying out these basic, yet important, tests you can safely sleep in your home on wheels knowing the fundamentals of your installation are correct.

Whether you’re testing a van conversion, boat, motorhome, log cabin or any other tiny build electrical system, these basic, yet important procedures can be applied to all electrical installations, big and small!

*For the testing of your 230v systems, we advise contacting a qualified electrician to test and inspect this part of the installation. The tests conducted require more complex equipment and a portion of the testing is carried out live and therefore needs to be conducted by competent person(s).