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Discussion Starter #1 (Edited)
My recently expanded HO layout (PDF attached) is DC powered. It has double reverse loops, which I've successfully wired to their own dedicated mainline direction and reverse loop center-off DPDT toggle switches. The reverse loop-operations function perfectly and as intended. (The two sets of double red lines within each loop in the schematic indicate that both rails are gapped.)

I don't believe the reverse loops are relevant, however, to my questions below (but I could be wrong!) and mention them here for informational purposes only (I hope!).

Please refer to the north yard and south yard tracks in the bottom right of the attached PDF track schematic (you may have to rotate it that so it's upright):

The Task At-Hand:

A) I want to wire each yard to its own dedicated center-off SPDT toggle switch so that each can be operated independently of the other (idle locos and a few cars will be parked there, next to the depot). Turnout #10 leading to both yards is a DCC-friendly Walthers/Shinohara, which will be operated manually.

In the schematic, the north rail of each yard's track is gapped (shown by the single red line) where it joins the manually-operated turnout.

Some Background

B) On a very similar, slightly smaller and recently dismantled version of the current layout (also with the same double reverse loops, north and south yards and one SPDT for each yard in the same location as in the attached PDF), I wired:

1. the ungapped rail in each yard to its respective toggle's center lug (yellow and red wires);

2. an end lug of the south yard's toggle to the center lug of the north yard toggle (white wire);

3) the blue wire from an end lug of the north yard toggle to the orange wire of the right-side loop's inside rail;

4) the other end lug of each yard's SPDT was not connected to anything

I'd attach the PDF of the old layout's wiring schematic too, but my scanner is currently not working. So I hope the wording above is clear enough to envision how the previous layout's yard-SPDT wiring was configured.

The Conundrum:

C) On the old layout, the wiring between the north and south yard tracks and their respective toggles worked as they should have (with a minor hiccup here and there), rendering each yard's tracks either "live" or "dead" when flipping the toggles.

However, when I tried duplicating this wiring configuration on the current layout, I got no current at all to either yard. I even switched the wires to the gapped rails as a test. Still no go.

My questions:

D) To which rail - the gapped or ungapped - in each yard should I connect a wire to the middle lug of its dedicated SPDT?

E) Is it even necessary to wire the two SPDTs together as described in "B) 2." above? Again, I want to have each yard operationally independent of the other.

F) Is it at all necessary to wire the north yard toggle to the right-side loop's wire as I did before?

As I recall, I thought this may have been the cause of the occasional hiccup I experienced when running a loco into and out of the yards. It seemed that the two toggles were at times in electrical combat with each other!

Lots of information, I know. Thanks for reading it over carefully and providing your thoughts and advice on exactly how I should wire the two yard tracks and their SPDTs.

If you have the capability, a detailed, color-coded wiring schematic would be most helpful. Visual helps a lot! :)
 

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in general, a DC layout is broken into isolated blocks that can be individually unpowered or connected one of several DC throttles.

sounds like you've isolated blocks by putting a gap in a single rail and have an ungaped common rail elsewhere except for the reverse sections (good).

it is not uncommon to have two throttles and use a SPDT center-off switch to be able to connect either or neither throttle to the block. I'd like to emphasis a single SPDT switch per block.


D) To which rail - the gapped or ungapped - in each yard should I connect a wire to the middle lug of its dedicated SPDT?
the switch is connected to the gapped rail to connect it to a throttle.

if you only have a single throttle, a STSP is required which either connects the throttle to the block or disconnects it from the throttle leaving the block unpowered.

if you have two throttles, a SPDT center-off switch would be used. the center or common switch terminal connected to the gaped rail and the other switch terminals connected to the throttles.



B) On a very similar, slightly smaller and recently dismantled version of the current layout (also with the same double reverse loops and north and south yards in the same location as in the attached PDF), I wired:

1. the ungapped rail in each yard to its respective toggle's center lug (yellow and red wires);

2. an end lug of the south yard's toggle to the center lug of the north yard toggle (white wire);

3) the blue wire from an end lug of the north yard toggle to the orange wire of the right-side loop's inside rail;

4) the other end lug of each yard's SPDT was not connected to anything
i found the above very confusing.

i will guess that you used a single center-off switch to connect a single throttle to one yard track or the other, or neither.

If this is what was intended, a single SPDT center-off switch could be used. The common terminal connected to the throttle and each of the other terminals connected to one (set of) yard track(s) or the other.

you can use a DPDT switch. 3 of the 6 terminals would be unused.
 

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Your north yard looks like my layouts removable section. I have gaps on one rail of each leg of the yard. Power to the track is connected from my throttle to the entrance of the turnout. Near the 9 in your picture. So the two tracks are dead with the gaps.

I have two SPST switches, one wire comes from the lead rail of the turnout, and connects to the yard rail after the gap, for both sidings.

The switch, when closed does the work of the rail joiner, if you get my meaning.

Nothing to do with the un-gapped rail.
 

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No way I could get my mind wrapped around the
series of SPDT switches you described to control
your yard spurs.


As Dennis has said, all you need is a simple on/off
switch (SPST) for each spur you wish to be able
to depower.

Each switch would have track power (right rail)
to one terminal, line to the gapped (right rail) of each spur
from the other switch terminal.

The ungapped (left rail) would get power from main
tracks of layout.

Note: Be sure to get power from the same rail
as you gap.

Are your turnouts power routing? If so you don't
need the SPST switches. Simply setting the points
to the main turns off power to the diverting track.
It restores power when points are set to divert.

Note #2: You can use your SPDT switches as SPST
by connecting power from track to center terminal
and line to gapped spur from either end terminal. Nothing
on the 3rd terminal.

Don
 

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Discussion Starter #5
Don,

The more complex wiring I had earlier and described in detail here was suggested a few years ago by a knowledgeable modeler and retired Milwaukee Road engineer I know. I think he had the SPDT center lug wired to the reverse loop power wire for just that very reason - to supply power to the yard. It worked, but perhaps was a bit over-cooked.

I believe your note #2 answers my main question and is much simpler. Thanks!

My turnouts are all-live (the newer version of the Walthers DCC-friendly), not power routing. Anyway, the turnout leading to the yards will be manually operated.
 
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