What gauge wire should I use for DPDT momentary toggle controls?


G

GuilfordRailman

Well-Known Member
Wiring and electrical work is not my strong suit. I’m in the process of preparing to wire up two DPDT momentary toggle switches to my Kato turnouts. The max amps for the turnouts is 3 with a recommended .5 to .8 amps for powering each turnout. I’m utilizing a 1.5 amp 12V wall adapter to provide power. My question is…what gauge wire should I use to wire the toggle switches themselves? The wires that are already present on a Kato turnout when purchased are 26 gauge so would 26 gauge work for the entire system, excluding the wire coming from the 12V 1.5 amp power supply? Here is a diagram of what the wiring needs to look like:

8B6B3F45-57B9-4BAF-84B1-6FA4B3EF4EE8.png
 
If you can always be certain that the maximum sustained draw through those wires is never going to be more than 0.5 amps, then you could indeed get away with 22-26 gauge wire, but even then for that smaller 26 gauge you would want it to be fleeting...say one full second and no more. Once you get upwards of 0.5 amps and draws lasting three seconds or more, you starting getting resistance effects and possibly excessive heating.
 
Selector said:
If you can always be certain that the maximum sustained draw through those wires is never going to be more than 0.5 amps, then you could indeed get away with 22-26 gauge wire, but even then for that smaller 26 gauge you would want it to be fleeting...say one full second and no more. Once you get upwards of 0.5 amps and draws lasting three seconds or more, you starting getting resistance effects and possibly excessive heating.
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Having momentary toggle switches will prevent this from occuring tho correct?
 
The problem is if you don't release it very quickly, it will over heat within a few seconds. It is easier to throw the switch and forget to remove your finger, than you think. I won't admit to that.😀 However, the real fun starts when the switches don't disengage, even when you do remove your finger. It has happened to me on a few occasions over the years. Glenn
 
That's why I always use a CDU, double safety, even if you keep your finger on the button or it fails, you still only get the momentary burst of power, before it switches off.
 
Capacitor Discharge Unit, just gives your turnout a bit more of a push, mine does 4 turnouts simultaneously, but can do up to 8, handy to use one, no motor burnouts, works like a momentary switch, with a bit more oomph :) you can make your own or buy one couple of $'s at most. Just google CDU Model Railway.
 
A quick search online for a chart showing the current carrying capacity of copper wire shows that a 26 gauge wire will safely handle 3.2A, bundled with other wires, continuously. You're not going to be drawing that much current, and certainly not continuously, so 26 ga. is adequate. As has been mentioned, it is probably easier and/or cheaper to get 22 or 24 gauge wire at your local hardware store. Even better. Smaller gauge number is larger diameter wire.
I suggest using solid wire, not stranded.

The OP indicated using momentary toggles. That's great.

About Capacitor Discharge Units (CDUs): also a good idea, but not mandatory. I've been using one for years.

The OP mentions a maximum load of 3A, with each turnout motor drawing 0.5 to 0.8 A, with a power supply rated 1.5A. The CDU will deliver the additional current pulse that the power supply will not.

My suggestion is to use whatever solid copper wire 24 gauge or larger that is easy to acquire. If you need to throw multiple turnouts at once and you can't, then I would put in a CDU.

Hope this helps!
Chris
 
Another factor not mentioned is the length of wire from the toggle to the switch machine. Most of my switch machines are located at least 10-12 feet from the control panel. I just looked in my wire storage cabinet and found a spool labelled "Atlas 20 ga. stranded wire" that has a pair of wires, one black and one white, but I have also used 22 ga. (smaller diameter), either solid or stranded. The most important thing is to keep your finger off the toggle switch once you have heard the switch machine "clack". In some cases I have also used rotary switches wired in series with momentary pushbuttons to indicate the route selected. As far as the use of a CDU is concerned, that is useful when you have a "ladder" of track, such as in a yard, where you want to set up a route with multiple turnouts. But, it isn't absolutely necessary. The old book, "How To Wire Your Model Railroad" by the late Lynn Wescott, describes some of this.
 
glenng6 said:
The problem is if you don't release it very quickly, it will over heat within a few seconds. It is easier to throw the switch and forget to remove your finger, than you think. I won't admit to that.😀 However, the real fun starts when the switches don't disengage, even when you do remove your finger. It has happened to me on a few occasions over the years. Glenn
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Good to know! Haha
 
Smudge617 said:
Capacitor Discharge Unit, just gives your turnout a bit more of a push, mine does 4 turnouts simultaneously, but can do up to 8, handy to use one, no motor burnouts, works like a momentary switch, with a bit more oomph :) you can make your own or buy one couple of $'s at most. Just google CDU Model Railway.
Click to expand...
Dang it! I already ordered my momentary DPDT toggles. Good to know for next time tho!
 
GuilfordRailman said:
Dang it! I already ordered my momentary DPDT toggles. Good to know for next time tho!
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😂 You still need them, You wire it in thru the CDU🙂
power to the CDU then to switch(s) then to turnout motor, the extra oomph is held in the capacitor on the cdu, when you push the DPDT switch it pushes that extra power through your switch to whatever motor it's wired to.
This gives a better description and has a wiring diagram.
 
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Railfan87 said:
A quick search online for a chart showing the current carrying capacity of copper wire shows that a 26 gauge wire will safely handle 3.2A, bundled with other wires, continuously. You're not going to be drawing that much current, and certainly not continuously, so 26 ga. is adequate. As has been mentioned, it is probably easier and/or cheaper to get 22 or 24 gauge wire at your local hardware store. Even better. Smaller gauge number is larger diameter wire.
I suggest using solid wire, not stranded.

The OP indicated using momentary toggles. That's great.

About Capacitor Discharge Units (CDUs): also a good idea, but not mandatory. I've been using one for years.

The OP mentions a maximum load of 3A, with each turnout motor drawing 0.5 to 0.8 A, with a power supply rated 1.5A. The CDU will deliver the additional current pulse that the power supply will not.

My suggestion is to use whatever solid copper wire 24 gauge or larger that is easy to acquire. If you need to throw multiple turnouts at once and you can't, then I would put in a CDU.

Hope this helps!
Chris
Click to expand...
Very helpful, thanks a lot! I’ll definitely be using solid wire. My micro layout only has two turnouts so it shouldn’t be a problem utilizing the momentary toggles.
 
trailrider said:
Another factor not mentioned is the length of wire from the toggle to the switch machine. Most of my switch machines are located at least 10-12 feet from the control panel. I just looked in my wire storage cabinet and found a spool labelled "Atlas 20 ga. stranded wire" that has a pair of wires, one black and one white, but I have also used 22 ga. (smaller diameter), either solid or stranded. The most important thing is to keep your finger off the toggle switch once you have heard the switch machine "clack". In some cases I have also used rotary switches wired in series with momentary pushbuttons to indicate the route selected. As far as the use of a CDU is concerned, that is useful when you have a "ladder" of track, such as in a yard, where you want to set up a route with multiple turnouts. But, it isn't absolutely necessary. The old book, "How To Wire Your Model Railroad" by the late Lynn Wescott, describes some of this.
Click to expand...
Or you could use these fitted into your board, Passing Contact Switch
PL-26R.jpg
 
trailrider said:
Another factor not mentioned is the length of wire from the toggle to the switch machine. Most of my switch machines are located at least 10-12 feet from the control panel. I just looked in my wire storage cabinet and found a spool labelled "Atlas 20 ga. stranded wire" that has a pair of wires, one black and one white, but I have also used 22 ga. (smaller diameter), either solid or stranded. The most important thing is to keep your finger off the toggle switch once you have heard the switch machine "clack". In some cases I have also used rotary switches wired in series with momentary pushbuttons to indicate the route selected. As far as the use of a CDU is concerned, that is useful when you have a "ladder" of track, such as in a yard, where you want to set up a route with multiple turnouts. But, it isn't absolutely necessary. The old book, "How To Wire Your Model Railroad" by the late Lynn Wescott, describes some of this.
Click to expand...
The overall length of any wire I’ll be using with the main power supply excluded is about 36”.

Since my micro layout only has two turnouts, I don’t think I’ll need to worry about installing a CDU. I’m still gonna investigate the concept because it could prove to be useful for a future build.
 
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