Tiny House Electrical Guide – Wiring & Powering Your Tiny Home

tiny house electrical guide
When building, tiny house electrical questions are bound to come up. I know I had a million of them:

  • How does a tiny house get power?
  • How do I wire a tiny house?
  • What kind of wire, outlets, and breakers do I need?
  • How much will it cost to wire my tiny house?

I want to dig into a lot of these bigger questions, then point you to a great resource that goes into a ton of detail on wiring your tiny home.

How Does A Tiny House Get Power?

How Does A Tiny House Get Power

For the most part a tiny house is set up just like a regular home, but some people who are more mobile opt to have a temporary connection as opposed to a permanent one. Whatever your approach, there are some technical details you need to follow.

Temporary Power Connections – 50 Amp Plug

50-amp plugThis is my preferred method and how I power my tiny house. I use a 50-amp plug from an RV supply store for about $30, plus an extension cord that I assembled myself by purchasing the ends and wire. The wire for a 50-amp drop cord is pretty pricey — $3 a foot if pre-made or $1.50 per foot if you do it yourself.

Essentially, this is just a giant outlet that pumps a lot of power through it. I’ve found with my local code enforcement that if I use this approach, it being “temporary” is a critical factor in being legal.

If my tiny house was hard wired, that would open up a huge can of worms legally speaking. Being that it is “temporary” by nature of the plug, building inspectors instantly lost interest, which is exactly what I wanted.
The other benefit of this approach is that you can roll into almost any RV park and plug in, which makes this a win-win in my book.

Tiny House Power Extension Cords

Tiny House Power Extension Cords

If you’re using a temporary power connection to your tiny house you’ll need a way to connect the house to your power source. The simplest way to do this is to buy an RV power cord. Keep in mind this needs to be sized properly to be safe.

Permanent Power Connection

Permanent Power Connection

The only real difference here is wiring the power line directly to the panel, without a plug. First you need to have your power box and power access installed and inspected. Then it comes time to actually connect the power to your house.

This is usually done by the power company who brings the line to your house and connects it to your power box. The key thing to remember is that each municipality will do this a little differently, and it will need to be inspected.

The National Electrical Code – NEC

The National Electrical Code

The National Electrical Code is the main code reference for you to refer to when it comes to all things wiring. This book is pretty dense, but for most things, you’ll be able to figure out the different key sections you need to know as you start to wire your tiny house.

Hiring an electrician is, of course, advisable to help you get the details right, and an inspection is always required. Electricity in a tiny house is a big deal, as doing anything wrong can create a dangerous situation that could lead to a fire or even death. Proceed at your own risk, as I’m not liable here.

guide to building codes and zoning for tiny houses
simple electrical for tiny houses

Calculating Your Tiny House Electrical Needs

Calculating Your Tiny House Electrical Needs

It’s a good idea to figure out how much power your tiny house will need and use for a couple of reasons. First, you want to size your power source coming into your house correctly. If you’re living off the grid, you need to make sure your solar panels for your tiny house are sized properly. You also need to make sure your circuits, wires, breakers, etc. are sized properly to make sure they are safe and up to code.

The good news is that calculating this in a tiny house is really simple. Since we’re so intentional about what comes into our house and we are often designing and building the house ourselves, we know exactly what is going to go in it. When I was wiring my tiny house and figuring out my solar panels, I literally had a list of everything that needed power in my tiny home.

The Basics: Amps, Volts, & Watts

The Basics of Amps Volts and Watts

I’m not going to get into a comprehensive guide to electrical theory, but there is one thing to understand that will make this all a whole lot easier:

watts equal amps times volts

That seems simple enough, but let’s take it one step further. If you remember back to your algebra days, sometimes your teacher would give you an equation where you had to solve for one variable, but it required you to move it around. If you were solving for X, you had to manipulate the formula so X was on one side of the equal sign and the rest of the variables were on the other side.

You moved things around by dividing, multiplying, and so on to shift things around where you needed them. That’s what we need to do here in a lot of cases because we may know two parts of the equation, but not the third.
For example, if we knew the watts and the volts, but didn’t know the amps, we could do this:

watts divided by volts equals amps

Another example is if we know the watts and the amps, but needed to know the volts:

watts electrical equation

So the one thing that makes this so much easier is realizing that watts, amps and volts are related. The interplay between them is proportional to the others.

A practical example is if a toaster says it’s 1200 watts and you need to know what the amps are for some reason, we can do the math quickly. Houses are most often 120-volt circuits (more on that below). That means we know two variables:

  • 1200 watts
  • 120 volts
  • We need to solve for Amps

solve for amps

How Much Electricity Do Items Use

How Much Electricity Do Items Use

Here is a chart of common things you’ll find in your tiny house and how much power they use.

common household items electric usage

120 Volt Vs. 240 Volt

120 Volt Vs 240 Volt

Much of your house in the USA is running on 120-volt circuits, but that will vary in other countries. Also in US houses, you will commonly find circuits that are 240-volt used for larger appliances, HVAC and other large power draws.

One thing that confused me at first is that sometimes people say 220 volt, 230 volt or 240 volt when talking about these types of circuits. There are technical differences, but largely they are referring to the same thing.

I say 240 volt, but what it really means is that instead of a single 120-volt wire going to that outlet/appliance, there are actually two 120-volt hot leads going to it. A 120-volt lead plus another 120-volt lead adds up to 240 volts.

In 240-volt wires, you’ll typically find a red wire and a black wire, which are the “hot” leads. You’ll also find a single white wire that is neutral and a bare copper or green wire that is ground.

Doing The Math

Doing The Math

I’d start by first making a full list of all the electrical items in your house (plug in and hard wired) and list them in a column on a spreadsheet. Then next to that column, have another column for watts, amps and volts. If you’re wanting to implement solar power, you can add an extra column for hours you’ll use each item in a day.
Then start filling in everything you know about each item. To find that information you can do the following:

  • Check the label, which usually lists some of the electrical numbers.
  • Go to the manufacturer’s website and find a spec sheet or manual for the item.
  • Use a Kill-a-watt plug in meter or clamp meter to measure it directly.

Tiny House Wiring Diagram

Tiny House Wiring Diagram

Let’s start out with an overview of how a tiny house is wired for electrical. Wiring your tiny house is dependent on your design and use, but in general, people wire their tiny house like this:

  • Left side of the main floor
  • Right side of the main floor
  • Loft
  • HVAC
  • Kitchen
  • Appliances
  • Other large draws

Each circuit should be designed for its expected load + 25% (as stipulated by code). That usually means a 20-amp circuit breaker on each circuit of your house except for appliances and HVAC, as they often are large draws.

I did mine a little differently. Here is a functional diagram of how my tiny house is wired:

power distribution from main breaker box

Here is a layout diagram of how I placed my electrical connections when I built my tiny house. You can see how this diagram differs from the functional diagram by showing the locations of the outlets, lights, fans and other connections. The functional diagram just shows how they’re all connected.

tiny house wiring diagram

how to build a tiny house

Electrical Drawing Symbols

Electrical Drawing Symbols

When reading a diagram or making your tiny house plans, electrical symbols are shorthand to know what goes where. They can quickly tell you what is going on within a house.

standard electrical symbols

Tiny House Electrical Materials List

Tiny House Electrical Materials List

There are a lot of elements that go into wiring a tiny house. Choosing the right components and connecting them correctly is key to a safe install. The NEC dictates many if not all of these considerations, so make sure you follow those guidelines.

Here are some of the key elements and my recommendations for them:

Tiny House Electrical Panel / Breaker Box

Tiny House Electrical Panel

breaker boxThe breaker box is the central hub of power for your entire tiny house. The power comes from a power source (the grid, solar panels, etc.) and then is broken down into smaller runs called circuits. My suggestion is to have at least 10 spaces in your box for an approximately 100-amp box.

In many cases, your power company will default to a 200-amp service, but you may be able to request a smaller one. Although it isn’t a bad idea to have a larger service and slightly larger box than what you think you need in case a need pops up in the future. Often the cost difference isn’t a ton.

Wire For A Tiny house

Wire For A Tiny house

The wiring for your tiny house will typically be done with Romex (a brand name used broadly to describe this type of wire), also known as non-metallic sheathed wire that is typically used in residential wiring.

One quick point I want to make about terminology. You have wires and cables. Wire is a single solid copper conductor, while cable is several strands of smaller copper conductors combined into a bundle. For the layman, we use the word “wire” casually, but for clarity, realize that what people often call a wire is often actually a cable.

wire types for tiny house


Wire Sizing

Wire Sizing

This wire/cable comes in a variety of sizes measured in wire gauge. The thing to remember about wire gauge is the bigger the number, the smaller the wire. Typical wire sizes for residential are 14 gauge, 12 gauge, and 10 gauge.

WIRE GAUGE RATED AMPERAGE COMMON USES
14-2 Romex 15 A Lighting Circuits
12-2 Romex 20 A Lighting & Outlets, Refrigerator
10-2 Romex 30 A Electric Water Heater, Baseboard Heaters
10-3 Romex 30 A Electric Clothes Dryer

Understanding Romex Labels

Understanding Romex Labels

Romex also come with different numbers of conductor strands that are bundled up to make the wire. Typically, you’ll have Romex with 2 conductors (plus a ground conductor) or 3 conductors (plus a ground conductor).

The wire labels on Romex packaging are a combination of the wire gauge, followed by the number of conductors that make up the cable. For example, a cable that is made of 2 conductors (plus a ground) that are 14 gauge in size, will be labeled 14-2.

12-3 romex label

Conductor Wire Color Coding

Conductor Wire Color Coding

In most cases, wire colors are used in a standard way, but you should never assume this. Usually the conductors in the wire are exactly the same, just with different color coatings for ease of keeping track of which one is which.
The most common convention for wire color coding is the following:

  • Black for your hot lead
  • White for your neutral lead
  • Red for your second hot lead in 240 volt
  • Bare copper or green for your ground
two wire cable color coding
three wire cable color coding

Color Coding Exceptions

Color Coding Exceptions

Wire colors often aren’t substantially different. When you encounter a wire, they are probably done correctly, but then again, if you didn’t wire it, you don’t actually know for sure. So be smart.

There are other cases where the colors will be different. The main one that comes to mind is in a three-way switch, it isn’t uncommon to find that the white wire is used as a “traveler” in the three-way circuit and could in fact be hot. To signal this, standard practice is to wrap tape around the white wire at all the boxes to signal this, but that doesn’t always happen.

If you know of other exceptions or tips, drop them in the comments!

how to build a tiny house

Circuit Breakers

Circuit Breakers

Breakers are safety devices that stop the flow of power when there is an overload or a short in the circuit. That means that they need to be sized properly for the application that they’re being used for. Below is a chart to give you an idea of common pairings.

In my tiny house, I had a 30-amp double pole circuit breaker for my minisplit and the rest were 20-amp single pole breakers.

wire gauge and circuit breakers

GFCI – Ground Fault Circuit Interrupters

Ground Fault Circuit Interrupters

You’re probably familiar with these because you see them in bathrooms. These are special breakers designed to stop the flow of electricity if it detects a “ground fault” in as little as 1/40th of a second. The idea here is that in wet environments, more risk exists. Code prescribes where these are used, so make sure to follow it.

AFCI – Arc Fault Circuit Interrupters

Arc Fault Circuit Interrupters

This is one you might not be as familiar with, but similar to GFCI, it stops the flow of electricity when it senses an arc. Arcs can happen from improper wiring, a nail being driven through wires, insulation being compromised, or some other issue. These are now generally required in all bedrooms and have been shown to reduce the risk of house fires pretty significantly. Refer to your local codes for guidance.

Grounding A Tiny House

Grounding A Tiny House

Grounding is a backup pathway for electricity to flow from the source to the ground so it can dissipate. You can ground your tiny home by connecting the breaker box ground bar to the trailer and to a grounding rod.

A grounding rod is a 10-foot copper rod driven into the earth with a copper conductor tied to it. You want to make sure there is a direct flow from the ground connection at outlets to the ground bar in the breaker box, and from there to the ground rod.

As a safety measure, we also ground the house to the trailer as well, so that if you’re driving down the road, current can flow down into the trailer and either dissipate through the foot of the hitch or arc a smaller distance from the trailer to the ground.

12-Volt Wiring For A Tiny House

12-Volt Wiring For A Tiny House

Many people have asked me about 12-volt wiring for a tiny house — mainly those who want to be off the grid. A lot of this comes from things you read on the internet saying that 12-volt DC wiring is more efficient than AC power, mainly because of the need to convert power from DC to AC.

This is generally a bad idea. Most of the advice to do this comes from a time when inverters were not as efficient as they are today. Solar energy has come a long way very quickly, so often articles and forum posts you’ve read are out of date. Even something as new as 6 months ago is considered out of date because of the pace at which solar is improving.

batteries for a tiny houseThe other argument for DC wiring on a 12-volt setup is that DC is more efficient in general. This is true, but it doesn’t tell the whole story. Consider that if you wire for 12 volt, all your appliances need to be 12 volt. That means the appliances you need to buy are around 3 to 5 times the price, and your options are very limited.

Any inefficiencies from the DC to AC conversion process can be overcome with the addition of an extra panel or two to your solar array. Switching to AC lets you have a huge range of options for a fraction of the cost of DC appliances. The costs savings alone, even after factoring in the price of an extra solar panel or two, will bust any myths about using DC.

So for this reason, I do not recommend anyone wiring their house for 12-volt DC power.

How Much Does It Cost To Wire A Tiny House?

How Much Does It Cost To Wire A Tiny House

The cost of wiring your tiny house will generally be around $500 in materials and around $1,000-$3,000 in labor if you hire an electrician. This does not include lighting fixtures and appliances, as they have a wide range of price points.

ITEM QUANTITY COST EACH
Romex-250 feet 1 $42.65
Outlets/Switches 15 $14.49
Outlet/Switch Covers 15 $0.49
Electrical Boxes 15 $0.68
Wire Staples – 225 pack 1 $4.83
Breaker Box 1 $43.67
Breakers 10 $4.18
GFCI  Breakers 2 $46.15
AFCI Breakers 1 $52.31
Led Puck Lights 3 $29.43
Bath Fan 1 $24.56
Total $625.31

Your Turn!

  • What’s your plan for wiring your tiny house?
  • Are you going to be on the grid or off the grid?
2 Comments
  1. Fans for under $30? You can find them, but you’ll hate how noisy they are! Count on AT LEAST $80/fan for a decent, energy efficient, and most importantly, a quiet fan.

    You also want to consider tools that will be needed if you do your own electrical work. The tools I CONSIDER essential that many people don’t already have are a voltage/continuity tester, a wire stripper, and a plug in receptacle tester WITH GFI tester function.

    Another thing for people who want to wire for temporary power – the inlet which FEEDS the distribution panel. Budget at least $40 for the inlet, heavier wiring from the inlet to the distribution panel, and “In Use” weatherproof cover – and that’s if you are only doing a 20-30A, 120V only power system! At the upper end, you’ll need a 50A 120/240V inlet, which, with box, wiring, and cover will easily top $100!

  2. Thank you Ryan for a great article. I will be sharing it.
    I agree with most of it. The exception being the use of 12 volt equipment. I think that depends a lot on how many how much.
    The only AC items I can see using are a refrigerator and the Air Conditioner. I’ve added extra panels for the fridge.
    If I went with all AC the inverter would have to be sized much larger. My roof is only so big so more panels is not an option.
    My needs will be served with only 500 watts of panel. Now If I could get more wattage from the same size panels……….

    Thank you Steven for your comment. It’s worth noting. Pricing and equipment changes.

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