Electrical wiring essentials: what you need to know to calculate, conn - knoweasy

Free shipping over 12.99 丨 30-Day Money-Back Guarantee 丨shipping: 2-3Days

Electrical wiring essentials: what you need to know to calculate, connect and install caravan and boat wiring

October 11, 2022

Does your caravan or boat need some electrical work done? The idea of doing your own wiring can be daunting, but it's actually easier than you might think. In this article, we explore the basics of electrical wiring you need to know when tackling your next project. This includes the tools you'll need, how to choose the right wire, and ultimately how to install it. Let's get started. 



Electrical wiring basics

  • Turning off the power before doing electrical work
  • Knowing how to use a multimeter
  • AC and DC lines
  • Insulating all wires

Calculate the correct wire diameter (AWG) for electrical systems

  • Based on load current (recommended method)
  • Based on fuse size

Select your wire type: stranded vs. solid

  • Recommended wire type: Stranded copper rated 221°F

How to connect the wires together

  • Method
  • Crimp Connector Material
  • Recommended Electrical Wiring Connector Insulation: Heat Shrink

Tools required for electrical wiring

  • Cutting and joining
  • Fixing and insulating tools
  • Safety tips: Insulating other tools

How to install wires

  • Cutting and stripping
  • Crimping and joining 
  • Safety and insulation



Electrical wiring basics


Before you start drilling and cutting wires, here are some electrical wiring basics. Even if you already know some of this information, it doesn't hurt to review it. 


Turning off the power before doing electrical work


Making sure there are no live wires in your boat or caravan is probably the most important thing you can do before you start an electrical project. You may think this step is obvious, but it's surprising how many people overlook it.

If you are sure which circuit you are dealing with, you can turn off the circuit breaker or pull the fuse, but if you are not sure, you may need to disconnect the shore power completely. As well as disconnecting the power from the shore power, you will also need to disconnect the battery from the main distribution box. If you have a battery disconnect switch, it is simply a toggle switch, but you can also disconnect the negative cable from the battery. 

Remember that even if you have switched off the power, you should always use a multimeter to double check that there is no power. To do this, first check the meter on the live circuit to make sure it detects voltage, then check the wires you are using to make sure there is no power. On higher voltage AC lines you can also use a non-contact voltage detector to check for power.


Knowing how to use a multimeter


As mentioned above, you will need a multimeter and you will need to know how to use it. The basic multimeter function measures the voltage, current and resistance in a wire. They can be helpful if you need to check if a wire is charged, what the voltage is or if it is connected. Your multimeter will come with a red and black cable that you can use to probe the circuit. It is helpful to have both a probe and an alligator clip so that you have your hands free when measuring power.

First, insert the cable into the multimeter. The black cable is plugged into the COM which stands for "common" and is then connected to the negative terminal of the circuit. The red cable is plugged into the VA Omega MA port and will then be connected to the positive side of the circuit.

Then, depending on what you want to measure (voltage, amperage or resistance), turn the dial and connect the probe or alligator clip to the wire or battery you want to check. Always remember that the black cable = negative side and the red cable = positive side of the DC circuit. If you turn it upside down, it will read negative.


AC and DC cables


When working in a caravan or on a boat, you will find that both AC and DC systems have a place in the electrical wiring process. AC stands for 'alternating current' and DC stands for 'direct current'. Keep these terms in mind as we understand the difference between these two types of power.

Essentially, AC power can be easily varied in voltage and transmitted over long distances without much power loss. This makes it ideal for use in the mainstream grid. In your caravan or boat, this is the shore power or generator power supply that powers your 120V or 230V circuit. These wires are usually black and white, with a "hot" wire and a neutral wire. These wires are not safe to touch when open and can be a shock hazard.

On the other hand, DC power is most relevant to battery power, as the energy stored in the battery is DC. DC power on a boat or caravan is usually 12 or 24 volts and is considered "touch safe" and not a shock hazard. The wires are most commonly red and black, sometimes black and white like AC.


What does this have to do with caravans and boats?

Your shore power is AC and your battery is DC. Therefore, to use DC power to power AC equipment, you must first connect the DC cable to the inverter. This is why an inverter is so important if you are going off-grid. It's also important to understand the differences, as running AC power through DC lines (or vice versa) can overheat the wires and possibly start a fire, especially if the cables can't handle the voltage or current.


Insulate all electrical cables


When you think of cables, you probably think of metal wires wrapped in some kind of plastic. This is because the metal wire is the conductor and the plastic is the insulator. Insulators protect the wires from coming into contact with other conductors (and thus creating short circuits). Most importantly, they protect you from electric shocks.

This is why it is so important to cover any bare wires and metal with insulation such as heat shrink or electrical tape. You don't want to accidentally become a conductor!


Calculating the correct wire gauge (AWG) for your electrical system


Now that we've covered the basics, let's talk about choosing the right wire for your project. Wires come in many variations, including diameter, length and type. Below, we'll discuss why it's important to know these specifications and which ones are right for you. 


Based on load current (recommended method)


When choosing the correct diameter, it is essential to know the load current that will pass through your wire. Firstly, the larger the diameter, the lower the gauge. For example, a 10-gauge wire will be thicker than a 20-gauge wire. It is also important to remember that the thicker the wire, the more amperage it can handle. Thus, a 10 gauge wire can handle 30A, whereas a 20 gauge wire can only handle 5A. 

This is why it is important to know how many amps will pass through the wire. You also need to know the length of the wire to determine the resistance, the number of volts that may be lost due to that resistance, the size of the fuse and the number of amps that will blow the fuse. After you know all of this information, you can choose the wire that can handle the expected current. 

If you are wiring a 12V battery or other large battery pack system, check out our article to determine the correct battery cable size for your system.


Based on fuse size


Although less common, you can also determine the wires you need based on fuse size. Each circuit on the main distribution box is rated for a certain number of amps. You can determine which size wire gauge you need based on the number of amps you can handle. You will also need to know the wire length and voltage drop to determine if you will have any energy loss. 


Choosing your wire type: stranded vs. solid


In addition to AWG, you must also choose the type of wire that is best suited to your electrical business. There are two different types of wire: stranded and solid. Stranded wire is manufactured in the same way as you might expect and is made from stranded metal wire. Solid wire, on the other hand, uses only a solid piece of metal as a conductor. 

Stranded wires have many advantages. They are flexible (and therefore easier to use), can handle vibration and are resistant to corrosion. The disadvantages? They are a bit expensive. Solid wires are usually cheaper; they are therefore popular for larger wiring jobs (e.g. house wiring).

However, they are more prone to corrosion, harder to wire, and they cannot handle heat or movement as well as stranded wire. It is also important that solid wires are not bent too sharply or they will break internally.


Recommended type of wire: Stranded copper rated 221°F


We recommend using copper stranded wire when wiring yourself in your boat or caravan. Not only does it perform well in terms of vibration, but it can also handle temperatures up to 221°F. This makes it the safest choice and easier to use. 


How to connect the wires together


Now comes the fun part: actually making the wires! Here we will discuss the different ways to connect the wires (including our recommended methods) and the various materials you will need. 




There are several methods of joining wires. These include crimping, soldering, twisted wire nuts and push-on connectors. Each of these has advantages and disadvantages in terms of ease of use, reliability and functionality. Nevertheless, we strongly recommend using a crimping tool to connect your wires. 

Crimping wires provides a safe and effective method of directing electricity through a boat or caravan. Wire crimpers are relatively inexpensive, provide reliable cold soldering (unlike push connectors) and are safer than other methods such as soldering. 

Torx nuts are never recommended for electrical installations on boats and caravans. This is because they tend to loosen due to vibration.


Crimp connector materials


The most common materials that can be used to connect wires are vinyl connectors, nylon connectors and heat shrink tubing. Vinyl and nylon are popular because they are inexpensive and relatively easy to use as you don't need any additional tools. However, they do not insulate the wire as well as heat shrink. 


Recommended insulation for electrical wiring connectors: heat shrink


We recommend using heat shrink because it protects against abrasion and sharp edges. It also provides an excellent seal against dust and moisture and provides clean structural support for your wires. Now, let's look at the different types of connectors. 

Termination rings: Termination rings are just that: a ring that attaches to your electrical cable. They connect the cable to a connection point in your boat or caravan, such as a stud or post.

Butt connectors: butt connectors connect two wires. They usually come in the form of a tube with a rolled edge at each end. You can get waterproof versions of these connectors suitable for connection in wet locations. These need to be heated to create a waterproof seal.

Disconnecting: Disconnecting isolates your wires from the mains (usually the main distribution box). 


Tools required for electrical wiring


Now that we've covered how to connect your wires, let's talk about the tools you'll need. As well as a multimeter, you will need several other tools to cut, connect, secure and insulate. Let's dive in. 


Cutting and connecting


Wire cutters/strippers: Wire cutters/strippers not only cut your wires, but also provide a safe way to strip external insulation. It usually has a variety of hole sizes to accommodate wires of different diameters. 

Wire Crimper: A wire crimper crimps two conductors together. It looks similar to a pair of pliers, but it joins the wires by clamping them together.

Hydraulic crimpers: Like the basic wire crimper, hydraulic crimpers press metal wires together to form a connection or joint. However, they are more suitable for larger cables and/or multiple wires, as they require a lot of pressure.

Cable shears: Cable shears are essentially heavy duty wire cutters. They come in a variety of sizes and strengths and can use your strength to cut even the thickest of wires. 

Heat guns: Heat guns are small, gun-shaped hand tools similar to hair dryers, only at a higher temperature. Together with heat shrink they can create an adequate seal when connecting wires. 


Fixing and insulating tools


Split loom tubes: To organise, protect and secure wires, you need split loom tubes. These are simple cylindrical plastic tubes that hold the wires together. 

Ties: Ties have several different uses for electrical cables. They can bind wires together and separate them when you have a bunch of cables in a small space. 

Cable clips: Cable clips allow you to install and run your wires along the desired route. They not only hold the wires together, but also secure them to studs or other connection points.

Rubber washers: The rubber washers help to pass the wires through the holes. They are round rubber pieces that protect the wires from sharp or abrasive edges. 

Electrical tape: Last but not least, you need electrical tape. This is an effective and inexpensive way of insulating electrical wires. 


Safety tip: Insulate other tools


Do you know how most pliers come standard with plastic handles on the handles? All your metal tools should be insulated in this way. Without proper insulation, your screwdrivers, spanners and pliers will become conductors if they come into contact with live wires. For better insulation, wrap your handles in electrical tape! Always do this when connecting or disconnecting batteries.


How to install the wires


Finally, we are ready to install the wires. Below, we'll discuss how to cut, connect and insulate your wires so you can finally get on with your boating and RV adventures. 


Cutting and stripping

Start by cutting and stripping the wire you intend to attach with your wire cutters/strippers. Stripping the wire simply removes enough insulation to make the connection. When stripping the wire, use the correct size hole and strip the wire, leaving only enough room for crimping and connecting. 


Crimping and connecting 

Now that you have cut and stripped the wires, it is time to connect them. Use your wire crimper and the appropriate connector or terminal to crimp the wires. Depending on the size, you may be able to choose a hydraulic crimping machine. 


Safety and insulation

Now it's time to insulate and protect the wires. If you are using butt connectors to connect the wires, use a heat gun to shrink the wrap around them until they are sealed. All wires must be well insulated (use electrical tape if necessary) and secured in place. You can use cable clips, rubber cable loops (when passing through holes) or cable ties. Most importantly, you should not have bare wires and your cables should be well organised to reduce vibration and any chance of damage. 


Recommended books for electricians

1.10 must-read books for electricians in 2021! Recommended by Master Electricians

2.Best Books For Electricians|Must-read books for those who want to become electricians

3.5 Best Home Electrical Wiring Books for Beginners | Electricians Guide

4.Top And Best Books And Guides For Electricians And Apprentices | Knoweasy Electrician Guide

5.The Best Electrician Books For Beginners: Top Six Sellers In 2022

6.12 Must ReadBooks For Electricians In 2022 Recommended By Master Electricians| Knoweasy Electrician Guide

Leave a comment

Comments will be approved before showing up.

Be The First To Know

Follow Us