My layout is 36 by 15. I am an accountant not an electrician. I bought and read Barry's book (great book) but I am still an accountant. I am going all MTH. All my track and switches are real track. I will have approx 40 switches. As I currently understand it I need to wire all of my Real Track switches back to the AIU individually. Do I have any issues with voltage drop to the outer switches
Replies sorted oldest to newest
You shouldn't, the switches take very little current, so the voltage drop on longer runs is minimal. In addition, they're designed to run on a range of voltages, so you have plenty of margin if you power them with 16-18 volts.
Depending on how far the wires are run you may have a minor issue with voltage drop, due to resistance of copper wire. A 40 foot run would be questionable to use the size wire recommended, so I would go up one wire size, from an 18 gauge wire to a 16 gauge wire.
Check around for wire prices as well, solid wire is usually cheaper per foot than stranded wire, neither wire is better for carrying voltages, both work the same. Home Depot will usually beat an electrical outlet on wire prices.
Lee F.
You shouldn't, the switches take very little current, so the voltage drop on longer runs is minimal. In addition, they're designed to run on a range of voltages, so you have plenty of margin if you power them with 16-18 volts.
Depending on how far the wires are run you may have a minor issue with voltage drop, due to resistance of copper wire. A 40 foot run would be questionable to use the size wire recommended, so I would go up one wire size, from an 18 gauge wire to a 16 gauge wire.
Check around for wire prices as well, solid wire is usually cheaper per foot than stranded wire, neither wire is better for carrying voltages, both work the same. Home Depot will usually beat an electrical outlet on wire prices.
Lee F.
OK, not to sidetrack, but I will anyway. I read the question this morning. It is a good question and you will get many answers that will allow youto wire your layout safely. I have seen many responses on switch wiring gauge, and wiring, in general. This is a topic where so long as you aren't way under gauge, you will probably be OK. The question coming in at what is proper/ way under gauge. This morning, I decided to read the O gauge companion and the DCS manual and am now confused.
1) What gauge wire is used between the TIU and first AIU? Between AIUs? How long are these wires?
This seems important (to me) because in this scenario, there will be 4 AIUs. Assuming they are under the bench at the layout mid-line, they could be 6 14, 22 and 30' down the mid line. Most wires added won't be more than 10 - 14' long. The majority of the signal and current will be carried from the TIU, through multiple AIUs before it hits the added wire. So, unless the AIU wiring is 16 gauge, I don't think we pick up much by adding 10 - 14' of 16 gauge wire to the end of the longest run, if the AIUs are connected by much lower gauge wire. Do we?
A better approach/reason to use 16 Ga wire, would be this: The cost difference between 16 and 18 is probably nominal, especially as a percentage of the layout cost. Get bulk 16 gauge in as many colors as you have uses. This allows you to start your wiring by having the blue wire ALWAYS through switches into the curve, etc. This way, in a pinch all but the largest layouts can run DCS and while you could make a wiring mistake, by mixing up your colors, you will always have adequate gauge, on hand, if you run out of blue and....
Just my ramblings.
Marty,
The TIU and AIUs are connected together using the cables supplied by MTH with the AIU. The connections between the TIU and its AIUs have nothing to do with wiring the accessories and switch tracks themselves.
The largest gauge of stranded wire that will easily fit in an AIU terminal is typically 18 gauge. However, I've had great success using 16 gauge stranded wire as long as I tinned the wire's end first.
This and a whole lot more is all in "The DCS O Gauge Companion 2nd Edition", now available for purchase as an eBook or a printed book from MTH's web store site! Click on the link below to go to MTH's web page for the book!
I can't imagine where you need heavy wire for individual switches, assuming you've fused the feed common to the AIU appropriately. You'll have a maximum of 10 switches connected to the AIU, so #18 or even #20 should be sufficient for individual switches. If you're truly anal, I guess you can fuse each switch, but I'd be quite happy with a 4-5 amp fuse for the common for all those switches.
Marty,
The TIU and AIUs are connected together using the cables supplied by MTH with the AIU. The connections between the TIU and its AIUs have nothing to do with wiring the accessories and switch tracks themselves.
The largest gauge of stranded wire that will easily fit in an AIU terminal is typically 18 gauge. However, I've had great success using 16 gauge stranded wire as long as I tinned the wire's end first.
This and a whole lot more is all in "The DCS O Gauge Companion 2nd Edition", now available for purchase as an eBook or a printed book from MTH's web store site! Click on the link below to go to MTH's web page for the book!
Barry,
On rereading, I understand better. I think...
newbe,
You have 2 considerations here.
1) wiring the switch throw to the AIU. 18 - 20 should be fine as John says, because that is just the throw and the wires are short
2) Wiring AC power to each switch. You don't want to power them off the track, as you don't want to run DCS signal through the switches. For powering the switches, you still need 16 Gauge ish, and probably want some guidance on what to use, to power that many switches.
So anticipating that question. What gauge? What PS?
Gentlemen,
I also used the 16 with great success, trim her up 1st however. GunrunnerJohn,
when you are a true PWE you install 3-4 Amp breakers for every switch, Ya Ya I know!
PCRR/Dave
Marty,
The TIU and AIUs are connected together using the cables supplied by MTH with the AIU. The connections between the TIU and its AIUs have nothing to do with wiring the accessories and switch tracks themselves.
The largest gauge of stranded wire that will easily fit in an AIU terminal is typically 18 gauge. However, I've had great success using 16 gauge stranded wire as long as I tinned the wire's end first.
This and a whole lot more is all in "The DCS O Gauge Companion 2nd Edition", now available for purchase as an eBook or a printed book from MTH's web store site! Click on the link below to go to MTH's web page for the book!
Barry,
On rereading, I understand better. I think...
newbe,
You have 2 considerations here.
1) wiring the switch throw to the AIU. 18 - 20 should be fine as John says, because that is just the throw and the wires are short
2) Wiring AC power to each switch. You don't want to power them off the track, as you don't want to run DCS signal through the switches. For powering the switches, you still need 16 Gauge ish, and probably want some guidance on what to use, to power that many switches.
So anticipating that question. What gauge? What PS?
One of the other things you could do if you have concerns is to use a PTC in each switch lead, say a 2A one. This will limit the current to what would be safe for most wire sizes you'd consider for switches, even smaller sizes. It has the bonus of not requiring any attention if there happens to be an overload, yet offers continuous protection.
One of the other things you could do if you have concerns is to use a PTC in each switch lead, say a 2A one. This will limit the current to what would be safe for most wire sizes you'd consider for switches, even smaller sizes. It has the bonus of not requiring any attention if there happens to be an overload, yet offers continuous protection.
Guys, what about running a 16 gauge buss "hot" power supply under the layout to cover all the switches.(at least the hot) I'm not sure how much current the lantern and controller bulbs will draw for each switch (3 of them) or whether newbe is even going to use the controllers? I think I'd also use 16 gauge for the ground side as well. How does the lantern pick up the comon if not using the controllers? Internally somehow via the track?
If you're running Lionel PW switches with incandescent bulbs, the previous advice probably doesn't apply. Those draw enough current to start to think about wire size. I was thinking along the lines of Fastrack or RealTrax switches.
gunrunnerjohn,
You are correct sir and the bulbs should be changed in both the switches and the contollers, it really makes a big difference. I get all that LED stuff from Scotts Odds & Ends, shipped right to my door. Even with the change out, remember the PW switches still takes more power to operate than any newer switch. There is a reason for all the transformers on our layout, we need more power to run all the old Lionel PW switches & accessories,
PCRR/Dave
Marty,
The TIU and AIUs are connected together using the cables supplied by MTH with the AIU. The connections between the TIU and its AIUs have nothing to do with wiring the accessories and switch tracks themselves.
The largest gauge of stranded wire that will easily fit in an AIU terminal is typically 18 gauge. However, I've had great success using 16 gauge stranded wire as long as I tinned the wire's end first.
This and a whole lot more is all in "The DCS O Gauge Companion 2nd Edition", now available for purchase as an eBook or a printed book from MTH's web store site! Click on the link below to go to MTH's web page for the book!
Barry,
On rereading, I understand better. I think...
newbe,
You have 2 considerations here.
1) wiring the switch throw to the AIU. 18 - 20 should be fine as John says, because that is just the throw and the wires are short
2) Wiring AC power to each switch. You don't want to power them off the track, as you don't want to run DCS signal through the switches. For powering the switches, you still need 16 Gauge ish, and probably want some guidance on what to use, to power that many switches.
So anticipating that question. What gauge? What PS?
Each AIU can only power 10 switches, so you will need 4 AIUs Not knowing what it will look like under your layout, I was expecting you would spread them across the layout and shorten the AIU wires.Since all power will be coming from 1 source, power wires will have a different pattern. Each switch will need 5 wires going to it. 2 for power, 3 from the aiu for switching. Sorry if I complicated things, by chiming in.
Access to this requires an OGR Forum Supporting Membership
