Electricity for Tiny Houses

Jeff and Arlene have been sharing some great info about how they are approaching their tiny house in terms of wiring.

ScreenHunter_01 Jun. 27 11.58

Before we get into it, a quick lesson:

Volt is the measurement for “force” behind a electrical current

Amp is the amount of energy in a electrical current

Watt is the amount of energy something uses (Volts x Amps)

They first determined what they use:

Its always good to design your electrical system to handle more than you think you will need for two reasons.  First is that if you do need a lil extra umph, you have it.  The second is a safety concern.  A system that is strained is a potential danger for fire, overload and other really really bad things.

I would always recommend installing a small circuit breaker between your power source and your home, this is a bit overkill, but it protects your investment ScreenHunter_02 Jun. 27 12.30and the things and people you care about.  Of course make sure you use electrical plugs with a breaker built into them in near the sink and in the bathroom.

Another interesting idea that I have found address the issue of the limitation of wall sockets / electrical plugs.  Namely there is only two sockets.  A Japanese (which I couldn’t figure out their company name) had came up with a design to address this, its called Node.   I could ramble on about it but a picture is worth a thousand words and its brilliant!

Check out Jeff and Arlene’s post here

  1. Nice post!
    Note that this estimate has everything ON, which almost never happens. In fact, my electrician friend told me that most systems are designed to handle around 1/2 to 2/3 of total POSSIBLE load with the expectation that no one ever turns on every item at once. That said, our system has two 15 amp circuit breakers and is wired to handle 30 amps.

    I just put up a new post on the topic which includes my design map for the wiring.

    • are you guys electricians? i’ve been taught that amps were the ‘push’ and volts were the ‘amount of energy’ when it comes to electricity. if volts were the ‘push’ then how could you survive a shock from a 110 volt outlet?

      • Volts are indeed the “push”.
        A shock from 110VAC hurts. If you’re in water or otherwise not we’ll isolated from ground it can kill you.

    • Link to your post?

  2. A water heater using only 0.15 AMPS?????? Are you sure that's correct. Most electric water heaters use like 30-60 amps, don't they??

  3. Yes. I'm sure. This is because it uses gas to heat the water, and but uses electricity to monitor water temp and for ignition.

  4. This writer makes some good and extremely safe comments about circuit breakers in front of your home. Commonly referred to as surge protectors, they protect your whole house form a spike of energy. Whole-house surge protectors can be quite expensive (at least in the Atlanta market) but a solution I use was to install individual surge protectors on any appliance with solid-state controls. So far so good!

  5. To clarify volts and amps. Volt is, as you say, force, and Amp is the quantity or volume of electricity flowing in the wire. A good analogy is the water one: Volts would relate to the pressure in a pipe, and Amps would relate to the diameter of the pipe.

    You say you "would always recommend installing a small circuit breaker between your power source and your home, this is a bit overkill,…" I don't know where you live, but in most places it is the law. It would be foolhardy not to protect the circuits in your home. Even if you had a breaker in every device in the home, you still want to protect the wires that run to these devices, which can get shorted and cook your walls.

    It sounds like you are describing GFCI outlets when you say they have a circuit breaker built-in. This is NOT a circuit breaker, it is a special safety circuit that detects tiny currents to ground that would occur if someone were getting a shock by touching a hot line and a ground, such as an electrical pipe, and if it detects such a current, it instantly shuts off the power to that outlet. But a GFCI provides no protection in any way for large overcurrents such as short circuits.

    You would be wise to have at least 2 or 3 separate branch circuits in your home. Most codes require a separate circuit for the kitchen, and it is a good idea to have one breaker on your light circuits and another breaker on your outlet circuits, just so that if you want to repair an outlet you can do it without a flashlight. Also more breaker circuits have the advantage of leaving most the house still functioning if a particular breaker blows.

    • Nicanor, thanks for the info on the breakdown for branches and breakers!

      When I design my house, I’ll be sure to keep that in mind. 🙂


  6. Howdy Folks,

    I came across your website from Tiny House Blog, and I like what I'm hearing. I did see some oddities with your power sheet as well. 150 watts for a laptop seems very high. They usually draw at MOST 40 watts in full use, with about twice that when charging a battery. And that is for the super powerful "Desktop replacement" style lappies. Many use only about half of that or less.

    I'll be adding your site to me RSS Agrigator, and I look forward to reading more. See you again soon.

  7. Nicanor: "Volts would relate to the pressure in a pipe, …"


    "…and Amps would relate to the diameter of the pipe."

    Not really. Amps (current) is more like the rate at which water is flowing though the pipe, in litres per second or gallons per minute or whatever. In fact, an ampere corresponds to 6.242 × 10¹â¸ (six and a bit billion billion) electrons flowing past a point in a second.

    Ryan Mitchell: "Amp is the amount of energy in a electrical current"

    No, see above.

    "Watt is the amount of energy something uses (Volts x Amps)"

    No, watts are a measure of power: the rate at which energy is transferred.

    The basic unit of energy is the joule. A watt is one joule per second. More commonly people use the unit of a kilowatt-hour for energy – that's 1000 watts for one hour (or 1 watt for 1000 hours, or whatever). See http://www.edavies.nildram.co.uk/2007/11/kW-kWh.h…

  8. Grant:
    The transformer for the laptop says 1.5 amps @ 100/240 volts. If watts=volts*amps, then 1.5*120=180. The laptop is actually a Levono X60 tablet with a 12 inch screen, so it isn't all that big. Now, the transformer puts out 20V @ 3.25 amps, which is 65 watts, but from the perspective of designing the system, I assumed that the transformers input was what was important.

    My system has 2, circuit breaker protected branches, GFI's in the kitchen and bathroom with other outlets downstream of them(such that they are protected too) and light switches on a different line than the GFIs (to help reduce GFI false alarms that can happen when switches and GFIs are on the same line).

    There is a map of the system here: http://mobilecottage.blogspot.com/2009/06/electri…

    • This makes everything so completely paenilss.

    • Jeff,

      I know that I’m late to the party, but the link doesn’t work for your map anymore. 🙁

  9. Ed: Thanks for the clarification. My memory was a bit hazy because I hadn't put the concept to words in a long time, so I hedged a bit by saying "related to" to save some thinking. <g>

    Jeff: The map makes sense. Your description in the article made it appear to me that you were confusing GFCI's with breakers.

    If you ever find out more about that clever outlet, post the info. I like it. I wonder if they could add a ring of ground connections in between the power ones. -I did see a new type of four-square outlet fixture by Hubbel that has each grounded outlet facing a different direction. That would be good for those right-angled ground plugs that often go the opposite way that you want.

    • It seems that it is only available in Japan.


  10. Just for clarification, this website is cross-posting comments because I have two comments reflected in this thread but only the comment about the water heater applies to this article. The other comment was posted to another article unrelated to this one, but somehow was applied to this article??

  11. I would be interested to see how many Amps and Watts are used when we leave a charger plugged in (phone, laptop, iPad, ect) and the charger is not charging our electronic device. I know better than to leave them plugged in when I’m not using them but I still do it. Maybe if I realized how many amps or watts I’m wasting I will think about it little more serious.

    • Carolleewth3

      Your charger draws no current when not plugged into a device. If it is unplugged and there is no current going out of it, there will be zero current in to it. Thus zero energy is being used.

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