Placement of power district kill switch?

[Cajonpassfan]

I'm thinking I need to clean up the rats nest around my N scale layout's main power supply/distribution point (see below) and could use some advice. I hate wiring....

I run NCE DCC on one 5 Amp Powerhouse booster, split into 8 power districts, each protected by DCC Specialties PSX circuit breaker (or breaker/reverser). Seven of these provide track power (and some accessory power), one is to be dedicated to yard turnouts (when I get to it) So far so good, things seem to be generally working well, and when a short occurs in a given district, the breaker kicks in and its LED flashes until the problem is found and fixed.

As I'm pondering the rewiring, I wonder whether an on/off kill switch would be useful in each district, and whether it should be between the booster and the PSX circuit breaker, or between the PSX and the track, or whether it makes a difference.

Did I mention I hate wiring?
Thoughtful feedback appreciated!
Thanks,
Otto K.

[Maletrain]

I would put it near the circuit breaker, wired between the breaker and the track.  That way, when I go look at the breakers to see what the problem is, and see one flashing at me, I can immediately remove all shorts in the affected district by throwing the kill switch, and then see if the breaker resets.  If so, then the problem is on the layout.  But, if it doesn't reset with the layout disconnected, then the problem is with the elecrtonics on the power side of that kill switch.

I would also make that kill switch a double-pole version that breaks both wires to the layout.  Circuit breakers only cut one wire.  There are some weird things that can happen when one (or more) circuit breakers are wired (improperly) such that one breaks one wire and another breaks the other wire.  Using a DP kill switch can help with that.

[peteski]

Sounds like you have a well-developed power scheme on your layout, with plenty of electronic circuit breakers (which seem to correctly do their job). . Why do you thing you also need redundant manual kill switches?  What purpose will thy serve?  When will you need to use them? 

A short with a power district activates its dedicated breaker which will but the power until the short is removed. The breakers are designed to to that. Rest of your layout is unaffected and keeps working.  Do you envision any type of operation where you will need to manually kill the power to a district?  If the layout develops some sort of a nasty short in the wiring which affects one of the power districts (the scenario which , if you do not mess around with the wiring, is highly unlikely), then you can just disconnect the wires from the terminals on the breaker and troubleshoot the short.

Sounds  like looking for a solution for a non-existing problem. Like you said, you hate wiring and adding a kill switch adds, IMO needles complication and another component which can fail (the switch).  I would leave things as they are.

[John]

Sounds like you have a well-developed power scheme on your layout, with plenty of electronic circuit breakers (which seem to correctly do their job). . Why do you thing you also need redundant manual kill switches?  What purpose will thy serve?  When will you need to use them? 

I have manual switches on my power districts .. and each major yard has a cutout switch as well .. helps with troubleshooting smaller sections

[Cajonpassfan]

Thanks for the thoughtful feedback guys, much appreciate all views!
Peteski, I agree the kill switches are not necessary, but I think they can be very useful, as noted above. If I'm going to be cleaning up the wiring, that would be the time to install them. Didn't think about using DP switches, but @Maletrain makes a good point; if I'm going to bother, might as well do it right.
Thanks again,
Otto

[peteski]

Again, since you had the current setup working for a while, how many times (and in what time span) have you had the need to cut out one of the power districts for troubleshooting?  Sure, adding switches can help, but is it really worth the effort?

If you insist, I would install the switches after each breaker. That way when you kill the district, breaker's electronic circuitry will not be affecting your meter readings.

[Ed Kapuscinski]

I didn't use switches, but I did use a barrier strip. I can do the same thing (it just takes a screwdriver). It's right at my command station so everything can be controlled centrally (to help with "Where the F is the short??" troubleshooting).

[mrp]

I use a toggle switch to break the circuit on both wires before the PSX stuff. My layout was started in 1995, when DCC was more a novelty item than anything else. The toggles predate the PSX breakers by a few years, and were put in place to help isolate short circuits. From a DCC perspective, you don't need these, as the PSX breaker isolates the short for you. I think there are 18 of them on the layout. When not in use, the toggles are turned off.

But, starting over, I would still use the toggles. I like to use programming on the main with my NCE system when using the 3 point speed tables for speed matching.
It works well, and is easy to use. However, the first thing it asks for is the loco address. If you miss it and just hit enter, you end up programming every loco on the main.
So, the toggles protect me from myself.

Michael Pennie

[TrainboySD40]

But, starting over, I would still use the toggles. I like to use programming on the main with my NCE system when using the 3 point speed tables for speed matching.
It works well, and is easy to use. However, the first thing it asks for is the loco address. If you miss it and just hit enter, you end up programming every loco on the main.

I've been programming on the main for years. I had no idea I was stepping softly around that bombshell. That's terrifying. I can't sleep anymore.

[Cajonpassfan]

Well, lol, I sleep well. My original question was about the placement of a kill switch associated with a breaker-protected power district, i.e. before or after the breaker/PSX. Thanks guys for your feedback and opinions. My opinion is that with a large layout,  there is a real benefit in the ability to insulate power districts for troubleshooting without the need to unscrew wires under the layout.

In addition, I learned the hard way there is a benefit in having separate on/off switches in areas where power tends to congregate, such as engine terminals and staging yards. Not only does it help with troubleshooting, but also prevents every single loco on the layout to be powered at once upon startup. These can be single pole switches controlling groups of tracks as in the example below. And it may help Trainboy sleep better....

And I thought DCC was about just connecting two wires, right?
Otto K.

[peteski]

And I thought DCC was about just connecting two wires, right?
Otto K.

It can be, depending on your layout size and how you wire it.
For example a HCD-size layout could easily be a 2-wire DCC layout.  Even larger one can by if you so choose it. There is also no denying that even on larger layouts the DCC wiring is simpler than a typical block-control DC layout.  And no worries about running over block boundary. DCC has its own set of headaches (like programming), and it is undeniably more complex system, with more possibilities of glitches occurring.

[BCR 570]

Hi Otto:

I installed kills witches for each power district on the advice of a friend, and have found them to be very useful on occasion.  For me (not an electrician) they were very simple to install and have proven to be worth the minimal effort required.

Like yours, my layout is divided into eight power districts each protected by a PSX board.  Along with my power supply and command station, these are located  underneath my helix:




From each PSX board, the track bus goes out to the Power Management Panel on the front fascia of the helix which includes the kill switches, and then back to the breaker panel and out to the runs around the layout.


The Power Management Panel includes repeater LEDs and the kill switch for each power district.  This photograph illustrates the panel with power on and a short induced in a power district:




The kill switches have proven to be useful in the following ways:

1. During construction, with tools lying around the layout, turning off power to power districts not in use eliminates potential shorts.

2. During maintenance, particularly when working on turnouts in yards, turning off power eliminates shorts from use of tools.

3. In case of accidental loss of control of a locomotive (failed decoder, loss of wireless signal), the kill switch can stop a runaway locomotive.

4.  When I go back to replace some earlier trackage on bridges, I will use the kill switches to prevent accidental operation into areas with impassable track.


I am no electrician and I cannot say that this is the way to go, but I can say that it has worked very well for me and If I were doing it all over again I wouldn't do it much differently.


Good luck with your wiring,

Tim

[Cajonpassfan]

Tim, that's just beyond pretty!! 
The neatness of your work carries out to beneath the layout as well. Thank you for taking the time to do the writeup and post the photos! I seem to have reached the same conclusions, and your wiring is inspirational.
Do you use double pole switches for each district, or is a single pole adequate?
Regards, Otto

[BCR 570]

Hi Otto:

I used single pole switches which have proven to be perfectly adequate.

Tim