Tuesday, September 11, 2012

Building a 4-Way Selector Power Switch for $6

So I posted something about how I had read that the average hobby woodworker with no dust control breaths in more toxic dust in a day that a professional woodworker with the full dust control mechanisms breaths in a year. With that, I made have made a stand for my cyclone filter and Shop-Vac. I am now working on building a home made a dust filter, for which there are many pictures on the internet and mine will be up shortly (I hope).

In building the dust filter, I managed to get a scroll cage furnace fan from a local AC company. The fan had four power wires to control the four speeds (High, Medium-High, Medium-Low, & Low). So off I went to supply catalogs and I was shocked at the price of a 4-way selector switch. I thought about it, and then came up with a cheaper plan.

This blog describes how to build 4-way selector switches by using several 3-way light switches from your local hardware store. So rather than several hundred dollars for the selector switch, I wired one up for about $6, not including other parts I had or scrounged for free. This switch could easily be extended into other types of switches for other types of fans or more complex items.

Disclaimer: Electricity is inherently dangerous and misuse can result in a fire, shock, injury, or death. You should never work on live electricity and therefore either unplugging the item or turn off the appropriate circuit breaker. Always double check to see that no electricity is running with a working voltage detector. If you are not comfortable wiring up simple electrical outlets, this information is not for you and you should stop to hire a professional. It is up to the individual to determine whether he/she is capable and competent to do the work following the information provided here. Always follow the electric code requirements specific to your area and before undertaking any electrical project, contact your local electrical authority and your insurance company to ensure that you comply with all policies, warranties, regulations and authorities concerning this work. Make sure all wiring is properly grounded. By reading further, you agree to hold this blog and its owner harmless for any property damage, personal injury and/or death, or any other loss or damage that may result from your use of the information provided. Ultimately you are responsible for your safety and you assume all risks from the application of any of this information.

So before going further to the diagrams and descriptions, make sure you know the basics of electricity, how to be safe with it, and how to wire up a basic electrical outlet circuit. If you can’t do a basic electrical circuit, you won’t be able to do this.

Let’s look at a standard 3-way light switch, like those on opposite ends of a hall controlling a light. The diagram below shows the internal wiring with the toggle switch up and down. Switching the toggle switch then changes which traveler is connected to the common. 

Now if you can bring the power into the common and connect the traveler lines on two switches, you can now wire a 3-way switch. Below is the simplest way to wire up a 3-way switch. There are many other ways to properly wire up a 3-way switch; however, if you don’t understand this simplest method, you won’t understand the more complex 3-way wiring diagrams. In the case below, the power is coming in the first switch on the common screw. Depending on the direction of the first toggle switch, the power is then either going down the black or red traveler wire within the wire set. If the second switch matches the same orientation as the first, the power can then go to the light to turn it on and return via the neutral line. If either switch is changed, the circuit is open and the light goes out.

Now that you understand a basic 3-way switch, let’s think of it differently. To do this, I have drawn the same switches upside down, as in the diagram below. In this case, you can now bring the power in and then have the toggle switch be a selector switch. In one position, you are sending power to line A and in the other position, you are sending power to Line B. If you start to try this, for sure, get a meter and check the continuity. You will see it works like the diagram below. 

From here, one can see that you can put use the basic 3-way switch to send power in one of two directions. If you put a second 3-way switch next to the first one, you are now having more options on where to put power. The first switch would send power to Line A or the second switch. From the second switch, you could then send power to either a Line B or Line C. One thing to also point out is if you are sending power to Line A, the second switch does not get any power, so it can be in any position.

Put a third 3-way switch in line, and you now have a 4-way selector switch. This is then what I did for my fan. In my blower motor, the power colors corresponded to High (Black), Medium-High (Blue), Medium-Low (Yellow), and Low (Red). In addition, the white was the neutral, green was the ground, and brown was for the capacitor. In trying to determine what color was what, I did some internet searching and found that different fans can have different wiring and eventually spent time looking at the small wiring diagram. Be smart, look at the wiring diagram for your fan to be certain. Also, once wired, use your electric meter to confirm everything is correct.

Below is then the wiring diagram and switch settings for my motor and the 4-way selector switch. My wiring diagram works great. In addition to the 3-way switches, I put a 60-minute bathroom timer in front of it. This will allow me to run the fan on low when I am working and creating dust. When I leave, I can turn it on high and let it run for 60 minutes to cut down on the dust. 

A picture of the final switches is shown below before screwing in the 3-gang box. The wires from the fan were not very long and had to be lengthened to run to the switches. The lines were extended with white wire and then color coded with electrical tape. Out of habit I wrap all of my wire nuts as there could be vibration and wrap the switches (although one was not before the picture was taken). The holes going through the wood are not grommet protect and do not need to be as the holes in the wood are much smaller than the holes in the metal.

Hope this was of interest to someone out there,



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