Of all the commercial breakers I see on the market, they ONLY break one leg of the input when there is an overload.
Personal experience has told me this is not enough when you have:
The possibility of misfed wires with other power sources (ie: Switch machine power)
More than one booster and you don’t properly isolate districts.
You can get a backfeed on the leg that is not cut off. This can send a lot of voltage or amperage through your booster. Your booster would take it till it burned up. Very few boosters look for backfeed current.
The only reasonable way to protect against this problem with large layouts is
Wire a 1157 bulb to the leg that is not on the breaker to limit amps.
OR
Buy something like a PSX-AR which has breakers on both legs…but cost a small fortune.
Depends on the layout size. a very small layout like mine CAN run DCC with “just two wires connected”, and it did for awhile. I added two sets of feeders on teh opposite side of the layout just cuz better feeding to the far side.
Being a simple man I am. Have you looked at the DCC specialties OG there is also an OG-AR. Tony’s has the OG for $25. Sometimes we tend to over complicate simple things like 2 wires.
Martin beat me to it, the PM-42 does break both wires. Sometimes there is an advantage to those ‘old fashioned’ mechanical contacts. Mine works great and doesn;t seem to have problems with my sound locos, both of which are Loksound. Oh and an old Soundtraxx LC. The lC has no keep-alive, and the Loksounds have always programmed just fine with no special boosters or anything. I stay away fromt he brand that requires a booster unless you do POM. I don;t care how good the sound quality is, the program issue is a design flaw plain and simply, and others have already solved it.
Unless your layout is so large and supports runnign more locos than you can power with a single booster, you really CAN get away with “two wires” You still need feeders, track is no better a conductor of DCC power than it is of DC. A 100 foot strtch of DC track with just two wires at one end isn;t going to work very well either. Breakers - NOT required. A layout will work just fine without them - but when someone makes a bonehead move and shorts the track, the entire layout will stop if no extra breakers are used.
I really do respect your experience and skills, but you just kind of stuck your foot in your mouth. All the excess wires came from a layout that was being converted from DC->DCC.
Some relays had as many as 24 wires coming off them. All of this old wiring was to maintain correct polarity when crossing from one throttle power district to another. A lot of if was for block occupancy sensor wires. There was also wire arrays for yard turnouts. (Each running off 25VDC) With DCC we could remove the old occupancy detection as the breaker also provided occupancy feedback.
Over half the wires were removed in the conversion I would estimate. More are going to be cut soon.
Well the problem being is its a very OLD DC layout. And over the years its been patched and patched again with no consistancy on wiring colors or types. (I guess you make due with what help, funds and equipment are available.) It was ingenious, but over the years it just became a maintenance nightmare.
Don, respectfully, my orginal post was just a little fun, since every time I talk about DC on this forum someone ALLWAYS tells me how DCC is just two wires.
Second, also repectfully, I understand you may be dealing with a club, or some other situation where many hands and/or lack of planning/docmentation may have been the order of the day, but as a retired electrical design draftsman and electrician, who 30 years ago installed some of the first computer based machinery control systems, and designed complex relay machinery controls before that
I gotta say, if I was in that club and no one really has much of a clue what the existing wiring was for, I would have pushed for simply running all new bus lines for the DCC system and not trying to patch into the undocumented old DC stuff myself. Trying to reconcile a system built up over years by people who are no longer members (and in an older club may not even be alive anymore) with a modern control system is just asking for trouble.
Our club modular layout recently converted to DCC. The existing DC wiring was mostly just isolating sidings to park trains on, the rest was a simple 2 cab system, nothing sophisticated. Nevertheless, in converting old modules to DCC, all existing wiring was first cut off, then a DCC bus wire was made with PowerPole connectors on each end, and new feeder drops were added on. And it all worked, first time out, mainly because shortcuts were NOT taken.
Sheldon,
Obviously, your original comment was sarcasm, and you admit that it was “just a little fun”. IOW, we’re not to take it seriously. But then you said that your “sarcasm still stands” and detail why that is so. Huh? How are we to decipher that? Sounds like it wasn’t “just a little fun” after all, and that it’s now a debatable point. Either it’s a joke, or it’s not. You don’t get to poke a stick at a position, retreat behind a wall saying it was just a joke, then continue to poke.
If it’s for a laugh, well, consider me amused. and we’ll move on to other things.
If it’s a serious debate point, then let me remind you that my layout is 25’ x 50’:
And that contolling my layout is just this:
Under my layout is just two wires: one red, one black, and both 14AWG (which you can see in both photos). I have no circuit breakers, no block detection, no signals, no PC connection.
So do you still know for a fact anything more than a 4x8 needs more than the famously advertised “two wires”?
As for sound locos, yes, if one has 40 of them all on the layout at the same time, then you’ll need to do something. Either isolate them with toggles or add more power or more circuits. But then that also goes for DC. If one wants 40 engines on a DC layout to all be accessible, then one must also isolate with toggles or do some fancy wiring.
But what do I know, I’ve only been running DCC for 11 years and DC for 9 before that.
Paul, Define “two wires” however you like, but as far as I’m concerned, every one of your drops is “two wires” and the bus is “two more”. 10 drops, one bus = 22 wires. And a hundred feet of wire is a hundred feet of wire, no matter how its connected.
“Two wires” is just that - two wires like the feeder from my transformer to my loop of EZ track under my Christmas Tree.
So by my definition two would work fine for a 4x8, as it gets bigger some more wires are needed.
If your power requirements are within the range of one unit, than fine, with enough drops you might power miles of track.
Fact remains most guys with 25x50 have or have plans for more than 4-5 amps of locos - then the fun begins - and you know it. It may not be what you need or want, but most 25x50 layouts are going to need powers districts and ciricuit breakers.
The other point follows, which was also made by many others in this thread - BECAUSE it is more than two wires, good wiring practice and documentation is necessary for a good result and effective trouble shooting of problems. If it was really two wires how could there be any problems?
I had already been doing this 20 years back when you started.
