Do I need isolating rail joiners?

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KevSR
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Do I need isolating rail joiners?

Postby KevSR » Thu Mar 20, 2014 7:09 pm

I'm in need of a straight answer to a pretty simple question which, no matter how many DCC forums, websites, books etc I check I have yet to discover. It is - Even though power is being fed to all tracks at once to keep them all live, does the layout still have to be split into sections with isolating joiners to stop the power flowing into the 'wrong' end of points, i.e. not the toe end? Help please!

georgehgv
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Re: Do I need isolating rail joiners?

Postby georgehgv » Thu Mar 20, 2014 7:26 pm

KevSR wrote:I'm in need of a straight answer to a pretty simple question which, no matter how many DCC forums, websites, books etc I check I have yet to discover. It is - Even though power is being fed to all tracks at once to keep them all live, does the layout still have to be split into sections with isolating joiners to stop the power flowing into the 'wrong' end of points, i.e. not the toe end? Help please!


Far from being an expert but in my experience no. Unless you design a figure of eight type layout like I have then it gets complicated. Just make sure you have plenty of track feeds (power supplies) to the track in particular to any sidings that would be isolated if the point is thrown if using insulfrog points. I use fishplates with wires soldered to them and loop together into a power bus, just make sure all are the same side of the rail. Best way is to mark a wagon with a piece of tape or similar, follow the track and make sure each rail has the same colour on the side the tape is on the wagon. Hope that helps.
Enjoying the ride playing trains like never before. Building a model railway but not too specialised.

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Roger (RJ)
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Re: Do I need isolating rail joiners?

Postby Roger (RJ) » Thu Mar 20, 2014 7:41 pm

KevSR wrote:I'm in need of a straight answer to a pretty simple question which, no matter how many DCC forums, websites, books etc I check I have yet to discover. It is - Even though power is being fed to all tracks at once to keep them all live, does the layout still have to be split into sections with isolating joiners to stop the power flowing into the 'wrong' end of points, i.e. not the toe end? Help please!

If you are using electrofrog points (AKA live frog points) then yes, you need IRJs on all the frog rails with the possible exception of points leading to dead ended sidings.

If using insulfrog points (AKA dead frog points) you would not normally need IRJs but it can be useful to use them to electrically separate section of the layout to help with fault finding. They can be useful to prevent short circuits when some locos pass through a crossover between tracks.

On large layouts they can be used to create separate power districts and on reverse loops and triangles (wyes) they are needed to prevent short circuits.

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carnehan
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Re: Do I need isolating rail joiners?

Postby carnehan » Thu Mar 20, 2014 7:44 pm

Yes, isolated joiners are necessary at the 'toe end'' as you have described. Therefore at each standard point you will need two isolated joiners. I used the little plastic fishplates and picked up a batch of these loose on ebay for a few quid.

Suzie
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Re: Do I need isolating rail joiners?

Postby Suzie » Thu Mar 20, 2014 11:00 pm

It depends on which points you have and whether you want to divide your layout up to limit the effects of accidental overload. There is good reason why you have not found a definitive answer.

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Peterm
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Re: Do I need isolating rail joiners?

Postby Peterm » Thu Mar 20, 2014 11:33 pm

I'm with suzie on this. More info' needed for a proper answer. Type of points, reversing loops, do you want sections / blocks, etc.
Pete.

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KevSR
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Re: Do I need isolating rail joiners?

Postby KevSR » Fri Mar 21, 2014 12:57 am

Just a termius - fiddleyard scheme, no reversing loops or anything like that. Insulfrog points throughout, & a turntable. I thought the whole point of DCC was to do away with sections and blocks? Think I'll stick with DC - a lot simpler

Dad-1
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Re: Do I need isolating rail joiners?

Postby Dad-1 » Fri Mar 21, 2014 9:25 am

KevSR,

DCC is much easier - If you're using insulfrog points in particular.
Don't use any insulated joiners, not needed. In fact for secure electrical
supply it's best for every piece of track to have it's own droppers for power.
No, that is an extreme, but you don't end up with dead sections of track.

Only if you use livefrog do you use insulated joiners, or other particular odd
requirements that you won't have. Someone can always dream up why you
can/should use, but believe me I have none on a 16 ft long layout with
10 points & 2 slips !! (all powered from the two wire DCC bus into 4
DCC point decoders).

Geoff T.
Remember ... I know nothing about railways.
viewtopic.php?f=22&t=32187 and Another on viewtopic.php?f=22&t=28436&start=60&st=0&sk=t&sd=a

Bigmet
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Re: Do I need isolating rail joiners?

Postby Bigmet » Fri Mar 21, 2014 10:06 am

KevSR wrote:... I thought the whole point of DCC was to do away with sections and blocks? ...

It can do, but that's a secondary outcome of what it is primarily intended for, which is high quality independent control of the locomotives. Because each loco now only runs when commanded to do so, there is no need for isolating sections to place locos off power while others run.

In the type of layout with the track you propose it can all be one section, very simple as Geoff has posted.

Here's what makes DCC extremely good for this type of layout. Because track power is 'full on' at all times, and each loco can have the decoder set up to optimise motor control, you get very reliable slow speed performance necessary for a terminus operation. When things get a little crowded and you need to find space for a couple of locos, any piece of track will do to park them. Similarly you can move a loco onto the rear of a train with another loco on the stops at the other end, with no need for any track switching. All this because you are driving locos getting full power at all times with optimised decoder set up, instead of varying the voltage on the track.

Should you go on to a larger system, and/or if you choose live crossing points, then insulated rail joiners will be necessary: exactly as they always have been on a properly wired DC layout. My first go in DCC was on a large layout constructed fully sectioned for 'cab control' using DC. I was very grateful for the sectioning when there was a short, made it easy to find where it had happened: switch out all sections, reset DCC system, switch in one section at a time to isolate the 'where?'. That's why the all DCC layout I am building is sectioned; not so many sections as for DC, just enough to help troubleshooting.

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Bufferstop
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Re: Do I need isolating rail joiners?

Postby Bufferstop » Fri Mar 21, 2014 10:27 am

It's been said many times but not often enough that a beginner might notice, "A layout correctly wired for DC will operate perfectly on DCC if all the section switches are on." The only change that's needed if you have live frog points is to gap the rail leading from the frog to a dead end and install 1 extra feed, if you want to stable a loco in there and have it ticking over.
Dad-1's comment about 1 dropper for each rail, is important if section lengths are long, That is, as he says, the extreme case and it applies equally to DC. My end to end layout if stretched out would be eight metres long. A quick count of the feeds necessary for DC leaves only 4 pieces of rail (flexi track) drawing power through a rail joiner. Where the track crosses a baseboard joint it gets a feed on each board. If I have to dismantle the layout, a quick slice with a slitting disc will part the rails and still leave them working.That's good enough for me.
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Suzie
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Re: Do I need isolating rail joiners?

Postby Suzie » Fri Mar 21, 2014 11:36 am

You are using Peco Streamline Insulfrog therefore you will need insulated joiners on the frog rails to prevent momentary short circuits (not required on other makes of dead frog points with more plastic and less metal in the frog area). That is the extent of what you need to do, other than that you just connect feed wires to each track section (not necessarily every piece of track) and the job is done - much easier than DC.

Unfortunately some of the short-cut bodges that can be used as a workaround to simplify things on DC wiring do not apply to DCC so just wire it correctly, and if required simply, for DCC and you will be fine. You will not eliminate all the shortcomings of dead frogs, but they will probably be less of a problem with DCC than if you go DC - it is a shame that you have already got the track since the simple DCC wiring for Electrofrog is the same.

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thebritfarmer
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Re: Do I need isolating rail joiners?

Postby thebritfarmer » Fri Mar 21, 2014 12:25 pm

I use Peco Insulfrog and I don't have insulated joiners. Never had any problems with short circuits either.
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Dad-1
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Re: Do I need isolating rail joiners?

Postby Dad-1 » Fri Mar 21, 2014 1:01 pm

Sorry Suzie you are wrong.
I will again repeat that you do NOT need insulated rail joiners anywhere on a insulated frog (Peco as well as others)
point.
The short that can be experienced coming off a Peco point is nearly always limited to older models where they had much
wider tyres.In such cases the wheel catches the frog end of the other track. By adding you are ensuring that the frog is
only supplied from the moving switch rail and the toe of a turnout, yes it can reduce shorting at the expense of a
slightly inferior electrical feed.

I also note that someone has suggested insulated joiners at the toe of a point ...... No not ever as this is the power
supply route.

Geoff T
Remember ... I know nothing about railways.
viewtopic.php?f=22&t=32187 and Another on viewtopic.php?f=22&t=28436&start=60&st=0&sk=t&sd=a

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KevSR
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Re: Do I need isolating rail joiners?

Postby KevSR » Fri Mar 21, 2014 1:22 pm

Thanks everyone for your replies, reckon I've got it now (electrics are not my strong point, as you might have gathered!). I had considered changing my pointwork to larger radius and using electrofrog, but having costed it that won't be happening for a while. As for feeds, my layout will basically consist of lots of sidings, no continuous run, loops or anything so I assume one or two feeds on each siding length will be OK (there's a plan on my layout post)

Lofty

Re: Do I need isolating rail joiners?

Postby Lofty » Fri Mar 21, 2014 1:46 pm

KevSR wrote:(there's a plan on my layout post


That will be here: Kev's Layout thread


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