Opinions Wanted. Wiring for Blocks and Feeders in DC

[dfocht]

Hello all - 

 I'm working on this layout that I plan on running in DC due to a bunch of old DC locos I have and my question is am I feeder happy?  I've insulated only one rail for each block but I want to make sure there is even power distribution across the layout.

The feeders in the front are 36" to 48" apart.

Also, (not to sound unintelligent) what would the power switches I need be called?

http://farm3.static.flickr.com/2500/4164645805_741ef9db37_b.jpg

Thanks,

Doug

[fwright]

Optimum feeder spacing depends on how well your rail joints and rail joiners conduct electricity over the long term.  The primary point of feeders is to back up the tenuous electrical connection at the rail joint.  If you choose not to use rail joiners at all as I have done in the past on some handlaid track, then a feeder is needed for every length of rail.  Unsoldered rail joiners are notorious for failing as conductors across the rail joints over time - especially if gluing ballast or similar activities.  Using fresh (new) rail joiners during track installation can help, as can crimping the joiners.

Since you only to switch a single rail, single pole switches are adequate for the block toggles (switches).  The number of positions depends on the number of throttles to be selected from.  If there are 2 throttles, a single pole, 2 position (or throw) switch is the minimum - called SPDT.  Center off toggles allow you to turn the block off completely without selecting either throttle.  DPDT center off toggles are frequently no more expensive than their SPDT counterparts, and offer an extra circuit for the second rail or for signaling or indicating purposes down the road.

hope this helps

Fred W

[dfocht]

Thanks Fred!

 I plan on having only one throttle and would like the engines parked on a siding until called upon.

Is there any benefit to insulating both rails to a particular section versus just one?

 

[AltoonaRailroader]

 On my first layout I only wired feeders to the insulated block rails and left the "ground" potential side all run together instead of matching a ground feeder to match every hot feeder. So, with regards to your layout, I would put a feeder for each insulated rail block A-J, then perhaps only a few ground feeder wires because your ground rail will all be connected without any insulation jumpers to break the circuit. Does that make sense? But on the other hand, if you want to put a ground lead all over like you show here you can do that too, I'm just letting you know that you don't necessarily have to.

[fwright]

dfocht

I plan on having only one throttle and would like the engines parked on a siding until called upon.

With only one throttle, you only need a single on-off switch for each block.  This is called a SPST.  But again the price difference is not that much, so if you think you might ever add a second throttle, or control indicators or signals, I would go with DPDT center off and only use 2 of the 6 terminals for the present.  If you are sure you will only be using the one throttle, the SPST is all you need.

Is there any benefit to insulating both rails to a particular section versus just one?

 

Not in a normal DC block wiring situation.  Sometimes if you are using power routing turnouts or are adding reversing sections, you will need to insulate both rails in places.  And if two or more DC throttles share the same transformer, you will need to insulate all blocks in both rails.  The latter is a requirement in common rail wiring - each throttle must have a separate transformer supplying it.

If contemplating changing to DCC, it sometimes is to your advantage to insulate both rails from the beginning and using DPDT toggles.

• on a larger DCC layout the track is often sectioned off into "power districts", each with their own booster.  Some DCC boosters don't like the feedback between units that can happen with common rail setups, so it is recommended that both rails be insulated between power districts.  Small layouts usually only have a single booster so this is not an issue.
• If you are contemplating being able to switch between DC and DCC operations, it might possibly be useful to insulate both rails to allow split operations - DC on one part of the layout, DCC on another part.  However, the dire consequences of even accidentally cross-connecting the DC and DCC units (burned out components) for a moment generally outweigh the benefits of a split operation.  Remember wheels spanning the insulated joint can serve as the cross-connect.  The recommendation is that all blocks be set for DCC or all blocks be set for DC - period.  If you are doing all DCC or all DC (as recommended), it doesn't matter whether both rails are insulated or not.

Again, hope this helps

Fred W

 

[grizlump9]

 first thing if you want to use common rail wiring for DC you need to ground the same rail all around the layout. (except for wyes or reversing loops).  i ran a number 10 ga. bare copper wire under all the benchwork in my basement and drop a ground feeder from the common rail down to it about every  6 or 8 feet.

 i like to use single pole 3 position (plus off) rotary switches to assign any one of my 3 control units to the individual blocks.  i am using Train Engineer fm remote controllers.   that lets 3 people operate at the same time. (a rare thing, but it does happen)

 i used one rotary switch for the entire engine terminal and turn the power on and off to the individual "spots" with spst toggle switches.

 each power supply feeds a color coded number 12 wire that runs under the entire layout like the bare ground wire and i tap those for the three control cabs going to each control panel on which the rotary switches and toggels are located.

 i solder every other rail joint and leave expansion gaps about every 6 feet alternating the loose or sliding rail in atlas code 100 flex track from side to side.

 i used a bunch of old telephone cable for my block feeders and even though it is a small gauge wire, it works fine for me if i just double it up.  not a problem since the cable has all the wires in color coded pairs.  single wire drops from the rail are only about 6 inches long and then it goes into double wire all the way to the control panel.

 that would probably be too light for a dcc system but it works fine for me and there is little if any voltage drop anywhere on the layout according to my test meter.  i only run a maximum of 3 atlas or p2k locos on a train.  longest blocks are about 25 feet and have 5 feeder drops from each rail to the control and ground wire.

 i got my rotary switches from W W Grainger and while the are pretty proud of their stuff, they had these on a closeout deal and i picked them up for about 3 bucks a pop.  there are several discount electronic oufits on the web and you can get spst or just about any other toggle switch from them at a good price if you shop around.   don't waste your money on the miniature or sub miniature switches.  go for the standard size one even it they cost a little more.  the ones with the screw terminals make life easy.

hope this helps even though it is probably more than you want to know.

grizlump

[MisterBeasley]

Basically, you can't have too many feeders.  There's a point where adding more has little to no value, but it still won't hurt.

[dfocht]

 Thanks guys! Good advice and I appreciate the help.