Wicked Tiny House Electrical System Overview - Part 2
January 10, 2019
Part one of the electrical overview covered the rougher side of the electrical work - how to calculate the potential load of the house, roughing in electrical cables, choosing a breaker box, why to install a transfer switch, and why you shouldn't use the cheapest possible extension cord to tie into grid power. This second part focuses more on the visible side of the electrical system including LED lighting, smart outlets, fans, and more.
Lighting - In order to reduce my energy usage as much as possible with the intent of running off solar power in the future, I choose LED lighting for all but two lights in the tiny house. One of the biggest issues that I ran into is that my house is framed with 2x4's and most lighting fixtures are designed for 2x6 or larger construction. The nice thing is that LED's have come a long way in the past few years in price, size, and quality. In my research I was able to find a number of low profile LED lights that fit my needs perfectly. They have a depth of less than one inch and require very little clearance, if any.
What I found in my research and through trial and error ordering multiple different lights from multiple different suppliers both in the USA and elsewhere is that most of these lights either come from the same factory or are the same exact design with minor tweeks. I ordered a $40 light from a USA based company and $15 light from China and they appeared and functioned exactly the same. I believe this is one place where spending extra money isn't going to get you a better product, at least as this time.
That said, I ordered a number of 3w round LED's to be used in my reading nook, bathroom, kitchen, closet, and under my cupboards. 8w round dimmable LED's were used in the main living area and the 15w LED's were used for outdoor "flood" lighting. I would recommend buying one of these and seeing how bright they are before deciding how many you need. I used five of the 8w LED's in my living area and probably could've gotten away with only two or three. These things really throw out some serious light!
In the kitchen I also used a set of under cabinets "puck" lights to eliminate any shadows that might exist under the kitchen cabinets. These lights really brighten up the counter top and really improve the lighting during meal prep.
While we are on the subject of LED's, you'll notice that sometimes there is an option for different "temperature" lights. For instance, the 8w LED's are available in 3000k and 5000k temperatures. The lower the temperature, the softer/warmer the light will appear. For instance, a typical incandescent bulb is about 2700k while fluorescent tube lighting is typically closer to 5000k. Most people will want to stay on the lower end of the temperature scale. All my interior lights are 2700k-3000k and my exterior lights are 5000k.
One other note about these LED's - they all run on DC power. If you read part one, you'll remember how I mentioned that I put all my lighting on its own circuits so I could be run directly off DC power. Well, since I am currently running AC power and these lights run on DC, each light have a AC to DC power inverter. Depending on the lights you choose, you may or may not need to make some modifications to these lights. For instance, the 8w LED linked below comes with a convenient junction box where your 120v AC power goes in, connects to the power inverter, and comes out as 12v DC power for the LED. The 3w and 15w LED's that I bought didn't have this junction box, so you'll need to provide your own. I actually went even further than this and cut all the power inverters off their LED's and put them all in one central location in the house and then ran DC from this centralized junction box to each LED light. This increased the amount of wiring I had to do, but decreased the number of junction boxes. To each his own. Proceed in whichever way you find most appealing.
LED Dimming - Anyone who has tried to replace an incandescent bulb that is on a dimmer with a LED has probably had to frustration of figuring out that traditional dimmer switches will not work with LED's or CFL (compact fluorescent) lights and that regular LED's can not be dimmed. I'm not going to go into the technical details of why this is, just know that if you want dimmable LED's you need to get LED's that are specified as being dimmable AND get a dimmer switch that will work with LED's. Most manufacturers of dimmable LED's will recommend specific dimmer switches that are compatible with their LED's. I tried three different dimmer switches and found that the Leviton switch to the right worked most reliably. I have two of them in my tiny and haven't had any issues yet. Also note the color of the other light switches in your tiny, as you definitely don't want to mix and match colors!
Smart Outlets - In addition to typical outlets (just get these at your local home improvement store), I installed two "smart" USB outlets in my tiny. At $20 each, these are worth every penny. You get two normal plug spaces along with two 2.4 amp USB outlets. These things are amazing. No more running around trying to find a space in the wall outlet or surge protector for a "wall wart" for your phone or other electronics. Just plug the USB directly into the outlet and let it charge. Using these outlets is one of the few times that I've actually had my electronics charge in their advertised time. We're talking less than an hour for a cell phone to charge from under 10% battery to full. Although you can easily swap out a traditional outlet for one of these at any time, do yourself a favor and install a couple of them to start. You'll be happy you did.
Ventilation - Everyone seems to focus on making their tiny as tight and energy efficient as possible, but many people forget that you need a certain number of air changes per hour/day in order to maintain good air quality and remove moisture from the interior of the house. This is even more important in a space as small as a tiny house, especially if you consider the amount of moisture that is released when cooking or heating with propane/gas. Typically 5-8 air changes per hour for occupied rooms is recommended for residential construction.
However, as we all know, tiny houses aren't typical residential construction. Technically, my tiny house would probably count as one large room, and would therefore require a fan that moves approximately 150 cubic feet of air per minute (CFM) in order to have 5 air changes per hour. That's just not practical. I ended up purchasing a fan that is adjustable from 50-110 CFM and installed it in the bathroom. My windows are typically open all day and night during the summer, and during the winter I will typically leave the fan on at 50 CFM. If I notice moist buildup on the windows when its cold, I'll up the fan speed to 110 CFM.
One thing I really like about this fan is that you can add a bunch of different functions to it as needed such as a timer, moisture sensor, auto on/off function, and a wireless remote.
I think that about covers the electrical system. If you're curious about something I didn't cover, or need some more detail about a certain bit of the system, shoot me an email!