As noted above, it depends on the use. The main factors are amps and length of the circuit, to avoid overheating or excessive voltage drop. So a DCC bus might be AWG 12, 14, etc. (depending on amps and length) and a decoder wire might be 30 or 32AWG. A practical consideration at the switch is how easy it is to solder to the tabs, in terms of the wire size, stranded or solid, etc.
I find the 24AWG red/black stranded auto zip cord type speaker wire handy for DPDTs for my Tortoise machines and LED building lighting. It's perhaps heavier than required but fairly robust under the layout if disturbed. For my DCC on layout program track DPDT I used the bus wire (16AWG in my case) as the toggle was a bit farther away from the track than best for my typical 22AWG feeder wires which I like to limit to 18" or so length.
Paul
Modeling HO with a transition era UP bent
What does the toggle switch activate? Is it track power, a turnout switch machine, incandescent building lighting, LEDs? The important thing to consider for wire gauge is how much power is going to go through it. Track bus needs much heavier wire than a structure light bus that only drives LEDs.
It takes an iron man to play with a toy iron horse.
Given that it's a short run, I don't think gauge is critical, 12 & 14 is too stiff and 28 - 30 ga is too small to see. 18-22 sounds good
Henry
COB Potomac & Northern
Shenandoah Valley
I guess I would use the same ga. that broke off, or as close to it that I had on hand.
18/22ga
I have a broken dpdt toggle switch on my DCC N scale layout and I need to add more length of wire to it because this is how it broke (wires were too short). What gauge wire should I use? It looks like it's an LED toggle switch (tiny) and it might already have led buss wire attached to it but I don't know that for sure because this layout was built for me by someone that has passed away so I'm nervous about using the wrong gauge wire. Thanks