This page is about the installation of electrical systems in earthbag construction domes and other dome-style eco-homes. It is part of the open source Earthbag Crowdfunding Campaign and open source Earthbag Village. It consists of the following sections:
NOTE: THIS PAGE IS NOT CONSIDERED BY US TO BE A COMPLETE AND USABLE TUTORIAL UNTIL
WE FINISH THE CROWDFUNDING CAMPAIGN AND ADD ALL THE VIDEOS AND EXPERIENCE FROM
AN ON-SITE ELECTRICIAN AND THE ENTIRE BUILD TO THIS PAGE. IN THE MEANTIME,
WE WELCOME YOUR INPUT AND FEEDBACK
The domes being designed for the Earthbag Crowdfunding Campaign integrate maximally space efficient furniture and appliance designs. The goal of this page is to teach people how to replicate these designs. In so doing, we are creating the most comprehensive tutorials available for earthbag construction. This will help to show people that sustainable and maximally space efficient construction can be equally (if not more) beautiful than traditional building, significantly more artistic and interesting, and a much more easy and realistic do-it-yourself project.
Dispelling the mystery and demonstrating a clear path for replication of earthdome electrical design is important to helping create mainstream adoption of this building approach. Most electricians and other builders have never had experience with earthbag construction so we are creating a resource people can use to understand the complete process. We are also creating this to combine into one place all of the necessary resources for replication because our research demonstrated a huge lack of comprehensive resources in this area. In so doing, we are providing an open source tool set that is both specific to this build and useful and scalable for other builds too.
When undertaking a project and acquiring tools and materials seek out those that best fit your situation. Quality of tools generally correlates with price, but thorough research can save you money if you have the time. What works for us, may not necessarily work for you, but in many cases it will. We share our list here with the hope that it will act as a useful guide for saving you time, money, and frustration. To fully engage in this action item you may require the following tools and materials. If you find a better substitute, please let us know.
|TOOLS AND MATERIALS DETAILS
|Circular saw for cutting 1 x 6’s & 2 x 4’s for formation of electrical box anchors and the interior stud wall.
|½” 20-volt cordless drill/driver with lithium-ion battery. The 18-volt drills are soon to be phased out and replaced by the 20 volt. The 20-volt are faster, more compact, and powerful. While the 18-volt model will complete the work, it may soon be impossible to replace the battery chargers, therefore it is advisable to purchase the 20-volt over the 18-volt. This drill is used for assembling the anchors for electrical box installation, securing electrical boxes to anchors, and drilling through studs in the interior wall for running romex. A drill of this kind is used extensively in most any building project if you are using wood as any component of your project. Different brands and models are available.
|3/4” boring bit for drilling through studs to run Romex wire. Check with your local codes, but generally you must have the holes centered in a 2 x 4, as you need to keep at least a 1 ¼” distance from the edge of the stud to the edge of the hole or it will require a metal plate. With 2 x 6’s and larger, centering is not critical as long as you maintain the 1 ¼” distance from the edge of the stud to the edge of the drilled ¾ ” hole.
|Sawhorses for cutting lumber and plywood. The homemade wooden version on top is less expensive but heavier. The plastic set on the lower right are durable and lighter. Sawhorses allow you to make cuts in a safe, upright, and comfortable standing position.
|Hammer for securing staples and electrical boxes.
|Eye protection and respirator should always be worn when cutting wood, especially pressure treated wood.
|A tape measure will find continued use throughout your project.
|Carpenter’s squares comes in many different variations, some have specific uses, all you really need is something that can measure and provide a straight line. There are many varieties of carpenter’s squares and triangles to choose from.
|Pencil for marking cuts.
|1 x 6 and 2 x 4 pressure treated lumber for electrical box anchors.
|8 gauge stranded THHN multi – purpose copper wire. This is the feed wire to each individual panel in the domes and is buried directly in the ground, negating the need for conduit.
|12 gauge Romex wire in the upper left is used within the stud wall runs, upper right is 12 gauge black single-strand wire (hot), bottom left is 12 gauge white single-strand wire (neutral), and bottom right is 12 gauge green single strand wire (ground). The three different single strand wires will be bundled and taped together, then pulled through PVC conduit.
|This shows the difference between 2 conductor cable (top) and 3 conductor cable (bottom). The uninsulated wire in each photo is the ground wire, while the insulated wires are the conductor wires. The 12-2 wire is used for general outlet wiring and is accompanied by 20 amp breakers, while the 12-3 is run between two 3-way switches. If you are utilizing 14-2 wire for switches and lights, you can use 15 amp breakers, but 12 gauge, required for outlets, necessitates a 20 amp breaker.
|Poly pull line is used for pulling wire through a piece of conduit, single strand wire can also be used, but the poly line allows for a better grip. Sometimes the pull string is left in the conduit, if one anticipates a new run installed later.
|Electrical tape for binding three separate single-strand wires together (hot, neutral, ground) in preparation of pulling through conduit.
|Plastic cable clips, (2 nail) and ½” steel staples for securing Romex wire to interior stud walls.
|Wire cutters for making clean cuts to wire.
|Cable slitter for removing outer insulation of Romex wire.
|Wire strippers for removing insulation on single-strand wire.
|Circuit testers are used for testing all outlets and circuits for function and proper wire hookup. If the wiring is not correct, the circuit testers provide an immediate indication of the problem and some will specifically troubleshoot the problem so all you have to do is correct the wiring. Circuit testers come in many different forms, purchase what is appropriate for your project. What is pictured here will certainly get you started. The tester on the right will indicate if you have power to specific wires or outlets. The yellow outlet tester on the left will indicate if there is power to the outlet and if the outlet is wired properly, if not, the series of lights references an index on the tester and you will know what the problem is and can correct it.
|¾“ schedule 80 PVC conduit for housing single-strand wire, purchased in 10’ sections.
|¾” PVC conduit clamp for securing exterior wall run circuits. In our case, the conduit is behind the plaster and we will not require these clamps. However if you are running conduit on the exterior of a stud wall, these clamps are required.
|¾” schedule 80 PVC sweeping 90 used when changing your run to a 90 degree direction.
|¾ “ schedule 80 PVC LB used if you have more than 3 consecutive 90’s, allowing for ease of pulling wire.
|LBT access fitting – a point to pull wire in two different directions.
|¾” schedule 80 pulling elbow used to create a tight 90 degree turn to facilitate pulling, reducing the radius.
|¾” schededul 80 PVC offset used for transitioning from conduit into electrical box.
|¾” schedule 80 PVC bends used for various angle bends for change in direction of conduit.
|¾“ male electrical nonmetallic tubing to schedule 80 PVC conduit adapter.
|This box is used at the end of an electrical run for a switch or outlet.
|This junction box can also be used for a light.
|This box houses multiple receptacles or switches.
|Switch or outlet box that allows for continued run of power to another box.
|PVC conduit solvent cement for securing conduit runs and fittings.
|Schedule 80 purple PVC primer used to to clean pipe and fittings before assembly.
|¾” black pipe used as a form to create a slot into the earthbags. The outside diameter of ¾” schedule 40 black pipe is 1.050”, the equivalent of the outside diameter of the conduit we will run in the domes, ¾” schedule 80 PVC. The black pipe is hammered into the earthbags as the courses are laid up, then removed and the indentation will harden, creating the form for the ¾” PVC for wiring, later inserted and plastered over the PVC and providing a raceway to pull wire and make repairs for the longevity of the dome without having to demo the plaster.
|2-pound fiberglass-handled rubber mallet for countersinking ¾ ” black pipe to create form for burying ¾” plastic conduit into earthbags.
|Plastic electrical box for interior stud walls.
|Duplex outlet for interior outlets.
|GFCI outlet for bathrooms, kitchens, crawlspaces, garages, and outdoors (used and required by code wherever moisture accumulates).
|Single pole 15 amp toggle switch upper left (with cover plate upper right). 3-way switch lower left. Lower right is a side-by-side comparison of a single pole switch and a 3-way switch.
|Regular screwdriver or interchangeable screwdriver for attaching faceplates. The second screwdriver offers multiple types of bits that are stored within the screwdriver and used for different sizes and types of screw heads. Use a hand-driven screwdriver to avoid breaking the faceplates.
|20-amp single pole breaker to control individual circuits.
|Electrical subpanel to house circuit breakers and control individual circuits. These come with various slots, depending on the number of circuits required. Always buy a subpanel with a few extra slots, in case you need to add a circuit or two in the future.
|2 ½” galvanized screws for securing electrical boxes to 2 x 4’s and 1 x 6’s to 2 x 4’s.
|Various types of screw bits with corresponding screw heads.
|Screw bit holder—a separate attachment for holding a screw bit, such as any of the above and others, when you are trying to insert a screw in a tight space and the width of the drill prevents such an action.
|3 ½” galvanized finish nails used in 1 x 6’s for securing anchors to earthbags.
The installation of electric in an earthbag dome home is a different process than in a conventional build, and has to be approached in a different manner. In a conventional stick-build, after the structure is closed in, all the electrical wire is installed. With an earthbag structure, the conduit (or UF-B direct burial cable) is run as you are building, otherwise you will have to chip into the hardened earthbags which is vastly more time consuming. With this in mind, and to make electrical installation as easy as possible, we will create an indentation channel by hammering ¾” black pipe into the soft, newly-filled earthbags, then removing it; resulting in a channel for placing the ¾” schedule 80 PVC conduit before hardening of the earthbags is complete. Outlet and switch boxes located on interior earthbag walls are made possible by fabricating wooden anchors within the walls during their construction. The interior stud wall mounts are completed the same as in a conventional build, with a stud side-mount plastic electrical box.
You will need a very clear understanding of locations of outlets, switches, and the subpanel so they are all conveniently located; the best approach for this is to create an electrical plan. Creating your electrical plan includes the following steps:
Here are the electrical layouts and plans for each of the Earthbag Crowdfunding Campaign domes to use as a guide or example:
To create your own plan, do a mental walk-through and visualization of what you’d like your electrical plan to be. Think about the function of the space you are creating and transfer what you imagine onto a piece of paper showing where you want lights and anything that an outlet will serve (stereo, bedside alarm, kitchen appliances, etc.). Keep rethinking and envisioning your space until you have determined the proper locations as it relates to the electrical boxes.
If necessary, delineate the perimeter of your dome with rope or garden hoses, scratch it out at the beach in the sand, stake it off with string in your yard, etc. so you can have the experience of physically walking through the space and imagining turning on light switches, plugging in appliances, etc. Local code may require an outlet every 12 feet and every 8 feet for counter tops. The subpanel will need to be conveniently located and easily accessible within an interior stud wall with all breakers labeled to the corresponding areas of coverage. Code may have requirements related to the subpanel location and meter placement too, check to be sure.
Here’s a video about how to install a subpanel:
In our case, we will locate our subpanel within an interior stud wall and it will consist of 2-3 20 amp breakers, fed by and 8 gauge feeder cable. For the Earthbag Village, this cable will be coming from another subpanel in the Tropical Atrium, with that subpanel coming off the main disconnect panel. Code generally requires an unobstructed access to the subpanel, so be certain it is openly accessible with no obstructions.
Here is a video tutorial walking you through how we installed the earth dome home subpanels for the Earthbag Crowdfunding Campaign:
VIDEO COMING: DOME HOME ELECTRICAL: INSTALLING YOUR ELECTRICAL SUBPANEL
In an earthbag wall an anchor, or mounting plate, is required to attach the electrical boxes to the earthbag walls. Because you have no stud wall to directly secure to, a simple wooden mounting device is constructed to act as a nailer for attaching and securing the electrical box to the wall and inserted into the earthbag courses during construction. Be certain to check the local codes for what is permissible. This phase of construction includes the following steps:
The first step in constructing an anchor is to cut a 2 x 4 to a length of 14” and 1 x 6 that is 16” long, using pressure treated lumber. Then hammer in several 3½” galvanized nails, randomly spaced, into the 1 x 6, driving them in all the way. Now flip the 1 x 6 over and repeat the process. This task is easily performed by setting the 1 x 6 across a pair of sawhorses. Now perpendicularly center the on-edge 2 x 4 on the 1 x 6 and secure with two 2 ½” galvanized screws; one screw fastened 1 ¼” down from the top of the 1 x 6 and the other 1 ¼” up from the bottom of the 1 x 6, slightly offset by ¼”, to prevent splitting of the 2 x 4. The end product is a 1 x 6 anchor plate (with a 2 x 4 mounting stem for an electrical box) with four protruding corners and two nails that will help solidify the anchor to the earthbags above and below. This, in addition to the pressure from the earth bags, gives stability in the wall to the electrical boxes.
Now match the electrical box up with the end of the 2 x 4 and secure into place with one 2 ½” screw near the top of the box and the other at the lower end of the box (offset if possible) as the existing holes in the back of the box will prevent rotation of the box. If the heads of the screws are smaller than the holes in the back of the box, simply add a washer to provide solid backing for the screw.
The anchor is now ready for installation into the wall. Make sure you know how many electrical boxes you require and make them up ahead of time. You will need them readily available to install as your walls go up. Remember that you must follow code requirements on the minimum/maximum heights of the boxes, making sure the face of the box is about 1 ¼” out from the bags so it will match up with the plaster for a flush mount.
This video shows the installation of the electrical anchors and boxes within an earthbag wall:
When locating anchors for switches, it is done the same way as for the outlet boxes, but an LBT box will be inserted at the junction to project the conduit up to a 4’ level where the switch box will be installed identically as the outlet box.
Here is a video demonstrating this process, as well as the construction of the anchors:
VIDEO COMING: DOME HOME ELECTRICAL: SWITCH INSTALLATION ANCHOR VIDEO DETAILING ITS RELATIVE POSITION TO WHERE THE CONDUIT LINE IS BELOW
¾” black pipe is used as a form to create a slot into the earthbags. The outside diameter of ¾” schedule 40 black pipe is 1.050”, the equivalent of the outside diameter of the conduit we will run in the domes: ¾” schedule 80 PVC. Once the electrical boxes are positioned, just after the bags have been laid, a form is used for creating the space to insert the conduit. First the black pipe is hammered into the earthbags as the courses are laid up; before they harden and at the location you desire for the ¾” schedule 80 PVC conduit. Next, remove the pipe and allow the indentation to harden, creating the form for the ¾” PVC for wiring. Later, you will insert and plaster over the PVC to provide a raceway to pull wire and make repairs for the longevity of the dome without having to demo the plaster.
Here is a video detailing creation of the pipe raceways:
VIDEO COMING: DOME HOME ELECTRICAL: FORM CONSTRUCTION OF PIPE RACEWAYS
An important factor to keep in mind about the electrical installation in an earthbag structure is that running wire can be performed in two different ways. The first is that once the boxes are mounted, you can run electrical wire from box to box in the recesses between earthbags if you use UF-B direct burial wire (code-approved, BUT CHECK WITH YOUR BUILDING INSPECTOR BEFORE INSTALLATION). This wire is much simpler to run, but is more expensive and challenging to strip, but you will not have to buy conduit.
The second choice is using either metal or plastic conduit. Using conduit enables adding more circuits in the future (depending on the size of the conduit) and/or replacing faulty wires without destroying your walls. Due to this benefit, we will use ¾” sched 80 PVC conduit and it will be covered with about 3” of plaster.
Here is a detailed video showing how to install conduit in an earthbag structure:
VIDEO COMING: DOME HOME ELECTRICAL: WIRE INSTALLATION OF SINGLE STRAND WITH CONDUIT IN EARTHBAG WALLS & ROMEX IN INTERIOR STUD WALLS (WITHOUT CONDUIT), INCLUDING LABELING OF WIRES BACK TO THE PANEL AT THE TIME OF INSTALLATION
On interior 2 x 4 stud walls, use a ¾” boring bit to drill holes in the CENTER of the 2 x 4 stud. Your code will most likely require 1 ¼” of solid wood on each side of the hole. Because a dimensional 2 x 4 stud is actually 3 ½” inches wide, the hole has to be centered to allow for the 1 ¼” of solid wood on each side of the drilled hole. If it is less than 1 ¼” code requires a metal plate on the edge of the 2 x 4. If your interior stud wall is built with 2 x 6’s, you still need the 1 ¼” solid wood edge. Because of the wider stud, centering is not necessary, but be aware the 1 ¼” solid wood edge still applies.
In the interior stud walls you will use staples for securing the wiring to the studs. CLICK HERE for an article with tips on using staples for securing wiring to studs.
Here is a detailed instructional video covering the drilling of holes for the wiring, running the wire, and stapling within a stud wall:
VIDEO COMING: DOME HOME ELECTRICAL: STUD DRILLING, RUNNING WIRE, AND STAPLING WITHIN A STUD WALL
Our electric heaters will be hard wired in (as required by code) and the custom and DIY murphy bed furniture will have wiring built in that we will simply tie in with the embedded wire to our Romex runs.
Some applications will require (if not, it is still suggested) dedicated circuits. This includes the following:
Work closely with a qualified electrician to assure you are running the proper sized wire and matching breaker for the above items.
Here is a video showing the heater and internal custom and DIY murphy bed furniture connections:
VIDEO COMING: DOME HOME ELECTRICAL: HEATER & MURPHY BED CONNECTION AND SHORT NARRATION OF DEDICATED CIRCUITS AND HOW IT RELATES TO WIRE SIZE AND BREAKER AMPERAGE
Once you have run the wire to all your electrical boxes, you can connect the wire to the outlets and switches. The electrical plan in our domes is relatively easy to set up and the four areas of most concern are the installation of:
The following is a series of 23 short and explicit videos covering the basics of electricity. This includes the four listed above in addition to the following related topics:
The entire series can be viewed in one showing by starting with the video below:
Here’s a video of the additional specifics you need to be aware of when installing switches and outlets in domes homes and/or a complete Earthbag Village:
VIDEO COMING: SWITCH AND OUTLET INSTALLATION DETAILS SPECIFIC TO DOME HOMES
For 3-dome cluster homes, the subpanel is located in the interior stud wall of the earthbag domes. For the complete Earthbag Village, each subpanel is fed from another subpanel in the Tropical Atrium that feeds about 10 domes and has a single cutoff switch to shutoff all electricity to those 10 domes in an emergency. From each individual dome, there will be 2-3 20-amp breakers that can be individually shutoff. This will allow for safe maintenance or troubleshooting of an individual circuit within any particular dome.
The components are as follows:
An 8-gauge feeder cable is run underground from the subpanels of the main disconnect panel in the Tropical Atrium. This line is buried 24” below ground and will enter under the earthbag walls to a point directly under the interior stud wall. Once that wall is built the feeder cable is connected to the subpanel. In the meantime, the excess wire is coiled and protected until installation.
Here’s a video showing how to run and connect your feeder wire:
VIDEO COMING: RUNNING AND CONNECTING THE DOME HOME FEEDER WIRE
We will use two or three 20-amp breakers, depending on the final heat source. Ideally, one breaker is dedicated to a heat source, another to half of the outlets and lights and the third to the remaining outlets and lights. Dividing the outlets and lights on different breakers then provides us with continued power and lights if one circuit goes down. Be certain to properly label the breakers so the proper breaker can be turned off in case of an emergency or for routine maintenance.
To avoid electrical shock, the installation of the subpanel & breakers and connecting of wires to breakers should be completed by a licensed electrician. Though it is a relatively easy process, if one is not familiar with the process, it can be dangerous. For your general knowledge we are including a video below, but we still advise a licensed electrician carry out the process.
The labeling of breakers in the panel is generally one of the last steps. To make the process as easy as possible, as you run a wire, either label the wire with a piece of tape or write on the plastic sheathing (if using Romex) where the circuit runs so in the end when it is hooked to the panel, you know exactly what area that particular circuit controls.
Here’s a video showing connection and labeling of the wires and breakers:
VIDEO COMING: DOME HOME ELECTRICAL: INSTALLATION AND LABELING OF SUBPANELS AND BREAKERS
Attaching faceplates to all your outlet and switch boxes is the final step for completion of the electrical setup phase. This process is the simplest step of all and includes the following three easy steps:
This is the final step to completing the electrical process. Categorize your face plates into two groupings: those that belong to outlets and those that belong to switches. Use a screwdriver to attach the faceplates to the electrical boxes. The screws are included and it is a quick process of inserting either one or two screws to attach the plate (depending on the size of the box). The final step is to test all your outlets with a circuit tester or by simply plugging in a radio or lamp and also turning on and off all the switches. Sometimes a switch can be faulty coming out of the box, so it is a good idea to test the entire installation to know if you have received a faulty product from the manufacture.
Here is a video of the face plate attachment and circuit testing:
VIDEO COMING: DOME HOME ELECTRICAL: FACE PLATE ATTACHMENT AND USE OF CIRCUIT TESTERS FOR TROUBLESHOOTING
Q: I know a little bit about electricity, do I really need a licensed electrician?
Absolutely. There are serious consequences when dealing with electricity. Don’t take any chances. Have a licensed electrician onsite for all electrical work performed.
Q: How do I know what sized wire to use?
If you don’t know, this is another reason to have a licensed electrician onboard. Incorrect sizing of wire can be catastrophic. If you want to know more about it, work directly with the electrician, ask questions, and learn it the proper way.
Q: Where do I use a GFCI?
A GFCI (ground fault circuit interrupter) is used anywhere there is an accumulation of moisture or humidity. This is required by code and includes bathrooms, kitchens, basements, garages, crawl spaces, outdoors, etc.