K

Kato's 8

Well Known Member
Hi guys!
I could use some basic info on the connections on a double pole double throw switch please. There are 2 rows of 3 lugs or terminals and I dont know for certain how which ones are hot and which ones are grounds. Im wireing a simple map light with both white and red led lights and so the lamp has three wires, one hot for each led color and a single ground. And then pwr supply is single hot and ground. So 5 wires and 6 lugs. I have and idea on the way its to be wired but not certain......Thanks!

My other Q is what is the difference between ON-OFF-ON and ON-NONE-ON?
while I was switch hunting, I came across this and wasnt sure which one to pick for my application. I got the first one. It seems to me they would be the same but......

Thanks!
 
Typical wiring for these switches is center terminal is common, top terminal is on when switch handle is down, bottom terminal is on when switch handle is up.

This is for either side of the switch, looking from the rear. What you have is like two switches (SPDT) in one body.

The On-Off-On switch will stop at any of the three positions, IIRC the On-None-On will not stop in the center.
 
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On a DPDT switch, the center pins are normally connected to power.

With the switch in the "down" position, the center pin is connected to the top pin. In the "up" position, the center pin is connected to the bottom pin.

The two sides are not internally connected. They work as independent switches.
 
You've got the wrong switch, but it will work.

Assuming you want a choice of red light, no light, white light, then choose just one side (3 lugs) of your switch and wire the white hot lead to the top, power hot (12 volt) lead to the middle, red hot lead to the bottom lug. Other side of your switch is not used (you could have gotten a single pole, double throw).

Connect all grounds to a common point, using whatever your grounding philosophy is.

If you wanted a choice of all off, red on, white on, red and white on, then you'll want two separate single pole, single throw switches; one for the red, one for the white.
 
Thanks for the info. I had it all wrong! I was thinking i needed the double pole to pick either the red or the white light. I wasnt wanting both at same time. But its good to know i can still use the switch. I should probably cut the othe lugs off dont you think?
I was thinking that the ground wire from lamp needed to run to one of the terminals on the switch but I guess it just grounds to the body like everything else...duh
Thanks again guys!!
 
Yes, just ground local.

I would not cut off the extra terminals, you may end up needing them in a later evolution of the plane.
 
There are a lot of variations of these things

It is important I think that you understand what you have. It would really be worth your time to test the switch you have.

I assume from your description that you have 6 terminals on the back of a box shaped body with a toggle on the side of the box opposite the terminals.

Standard orientation for this discussion - If you hold the body of the switch so the the toggle is facing your right and the terminals to your left with two terminals on top, two in the middle and two at the bottom - the toggle motion is up and down.

The two rows of three terminals away from you is one internal switch and the three near you are the other and the only connection is the mechanical operation of the two electrically independent internal switches by the single toggle.

Physically this is not precisely how the switches are configured (they are not all the same) but you can visualize the toggle with a pivot axis inside the switch body and it extends to a pair of metal sliders that have a length just adequate to short across two terminals of their respective switches when the toggle is moved to the extreme end of its travel. In other words as everyone has said:

If the toggle is moved down the sliders on the end of the toggle opposite the pivot point are moved up and the two center terminals of the electrically isolated internal switches are connected to their top terminals.

If the toggle is moved up the sliders on the end of the toggle opposite the pivot point are moved down and the two center terminals of the electrically isolated internal switches are connected to their bottom terminals.​

The function of the switch does not care what you connect to what terminal, it is up to you to design how you want the toggle action to route the electrical current. You might realize how you might want to use such a switch to apply DC current in one direction in a circuit for one direction of toggle "throw" and the opposite for the other. Lowering and raising the flaps for example where you could connect the power to the top terminal of one internal switch and the bottom of the other and ground the other two top and bottom terminals and connect the two middle terminals to the motor other polarized device to make it go one way for the up toggle throw and the opposite for the down toggle throw.

Ok now for some of the switch variations.

Two position - Some externally similar switches have only two positions of the toggle so at the end of the toggle transition the switch commons (center terminals) are either connected to their top terminals or their bottom terminals. These switches have no center detented position where the commons are not connected to either the top or the bottom terminals.

Three position - This sounds like what you have. These switches have three detented toggle positions where the center is the off position

Momentary positions - Some externally similar switch common terminals (center terminals) are connected to the selected top or bottom terminals only as long as you hold the toggle in the desired position and when released the toggle returns to the center "off" position. This momentary function may apply to both toggle throws (like the flap switch) or only one (such as you might want for a test or pulse in one direction and latched on in the other).

This is just something I will throw in about switches that really does not apply to you immediate case. Panel space became a little tight for me because I wanted to leave some space for a storm scope after I had the airplane flying (that never happened but I needed the space for another mod so it worked out well). I selected several combination switch/circuit breakers for my panel where one switch envelope contains both functions.​

I suggest getting an ohmmeter or a battery and a light and test your switch so you know exactly what you are dealing with.

NEVER EVER STRESS THE PHYSICAL SWITCH BY DOING ANYTHING TO IT'S TERMINALS EXCEPT CONNECT WIRES TO THEM - OR NOT.

Bob Axsom
 
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I assume you have not purchased a switch yet.

If you use an ON-OFF-ON switch you only need a single pole switch. Power in the center and red and white on the others.

The best way, IMO, is to have a switch with the OFF position down and up for the other two positions. This would require an ON-ON-ON, (2-10), double pull double throw switch, wired IAW drawing 11-7 in Bob Knuckles book.

The 2-10 switch is a versatile switch which can be wired in many different ways to perform as needed.

George, RV8 1250+ hours
 
Thanks for such detailed response! That realy helped me understand what's going on with the switch and what I was doing wrong.
I did purchase a couple of the double pole micro switches and I can use them if I choose as was pointed out or I could just buy a couple of single pole double throws. I appreciate the help very much!
Bill
 
Get the book

Hi Bill,

I would also echo the recommendations to get Bob's book and a multimeter so that you really understand the switch and all the other electrical stuff you are going to install. I was not looking forward to wiring my 8, but after reading Bob's book I found this part of my project very rewarding.

http://www.aeroelectric.com/Catalog/pub/pub.html

Best $18 you can spend on this topic.

Regards,
Mickey
 
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