DCC wiring - is Automotive cable 32/0.2mm suitable

[Michael-554685]

Wish to purchase reels of RED & BLACK 32/0.2mm for OO gauge Large layout, available from Amazon today in 50M lengths, advertised as General Purpose with cable diameter being 2.1mm for my BUS. I already have droppers with fishplates attached. I am unable to solder under the baseboards which are fixed, I wish to carry out the task easily using scotch lock connectors because of my age & lack of mobility. Also have posted on Amazon and requested what maximum rating 5Amp or more the product is specified as this is missing. The Amazon cable is of reasonable cost compared to many other suppliers is the reason for this topic.

Anyone prepared to advise me on this matter please. PS Only using Hornby Brand New Track on my layout.

Michael

[96RAF]

The bus wire cable you are looking at is suitable for the job. Droppers can be of lesser gauge. I use stripped out mains cable as it is dirt cheap in large reels. Ring main for bus wires and twin core lighting flex for droppers.

Using wired fishplates is connecting into the worst possible place for bus droppers. Fishplates work loose over time hence the thing you are trying to avoid is the thing you are depending upon for electrical reliability.

Regardless of that if you cannot solder under the boards can you solder to the outside of the rails on top of the boards. If so use that method.

As to connections under the boards - scotch-locks/suitcase or insulation displacement connectors to give them their correct name depend upon use of matching gauge wires for the connector colour being used. A better way is to use Wago style connectors which come in various ‘ways’ e.g. 3-way, 5–way, etc or you can use simple screw terminal strips i.e. choc blocks.

[Brew Man]

Yes, WAGO is the WA y to GO. They are brilliant and no fiddly screws to get lost on the floor. I also use solid core mains cable for the bus but 16/0.2mm for the droppers solders to the outside edges of the track. soldered fishplates are a no-no. Can't think what Peco were thinking by offering them.

[37lover]

You guys really annoy me by stating soldered fishplates are a no-no. They may not be as good as soldering direct to rails but my layout has been running for over 12 years with soldered fishplates and no dead spots yet. Admittedly almost all my fishplates are connected so there is a lot of inbuilt redundancy. So please stop saying it is bad practice, it may not be the best but it is okay.

[rpjallan]

You say you have a large layout so I would be going for something bigger than 32/0.2 if I was you. Better to build in a bit of redundancy (for want of a better word). I also agree about soldering droppers to fishplates. That is a last resort. Having said that, we all have to make compromises sometimes…

[96RAF]

I had my solenoid points and track bus wired with ex-Cat5 network cable twisted pairs on one layout. The points worked adequately using a CDU but I certainly wouldn’t recommend anyone else doing it. The cable was rescued scrap and all I had at the time.

[morairamike]

Layout is DCC. My buss is 1.5mm household power cable. The buss runs from the power unit Gaugemaster Prodigy 2 in two directions, clockwise to the access flap and anticlockwise to the other side of the access flap. Both halves are terminated with a snubber.

My droppers are 7/0.2. each piece of rail has a pair of droppers soldered mid way along the rails.

My points are powered from CDU via 7/0.2 wire.

No problems encountered with either track power or point operation.

[Flashbang]

Hi

My rule for wiring is very simple and ensures 100% reliability DC or DCC. It has never let me or anyone Ive advised down if followed.

7/0.2mm LED wiring, colour light signals, building lighting plus street lighting and rail feeds for DC plus droppers for DCC when every section of track has a dropper pair.

16/0.2mm for all solinoid point motor feed wiring and the return where just one motor is being operated. DCC rail droppers where every track section is not dropper feed.

24/0.2mm for solinoid point motor returns where two motors move together.

32/0,2mm minimum size for DCC track bus feed wires. Solinoid motor return wire where three or more solenoids all move together in conjunction with a CDU (Capacitor Discharged Unit)

Note a CDU is often included in a DCC Accessory point decoder but always check if obtaining one for solinoid point operation. e.g. Hornby has one CDU shared between all four outputs, DCC Concepts has one CDU per output

If your layout is fixed and not able to be moved then a solid wire can be used for the DCC track feed bus pair, here 1.5mm2 is about the smallest I would recommend.

[rpjallan]

Here is a link to an interesting discussion on bus wire size (among other bus discussions) on DCC Concepts Focus Forum for anyone who is interested. This is a recent discussion and they have given me permission to link to it on here:

https://www.dccconceptsforum.com/post/cobalt-ips-losechange-address-12297737?&trail=15

[ColinB]

I must admit I use 7/0.2 wire everywhere and I use DCC. Admittedly I use separate sections so probably the wires are paralleled up, but for points I use the same. The current when you flick the point is only on there for seconds so 7/0.2 should be adequate, the only issue is the impedance on long runs, although I do use thicker wire for the return as it is commoned with each point. Then you have the issue that the thicker the wire the less flexible it is. I solder to the outside of the rail, by the time you have ballasted you can hardly see it, so you could run the wires across the top of the layout if you camouflage them. Again that is where using thinner wire helps. I must admit I hate scotchlock connectors as on old cars they always seem to give issues, but perhaps in this environment they work ok.

As for soldered fishplates I have enough issues on flex track and points with fishplates with out the complication of wires, but if they work for you then there is no issue. Because of my background in electronics soldering to the track is always my preferred way.

[Brew Man]

I have so far used 16/0.2mm wire for track bus droppers and multi-strand speaker cable for a DC bus with 16/0.2mm for point feeds. Recently I thought I'd get some 7/0.2mm to try out. I must say I find it a bit light weight, but everything, (so far) appears to be working OK. I do think I'll revert to 16/0.2mm though, if only for peace of mind.

[96RAF]

I have used this for solenoid point motor wiring on my latest layout. It definitely works and just fits in R8247 terminals.

https://www.dccconcepts.com/product/solenoid-connection-wire-3-plait-redblackred-2/

Label says 32/0.2

[Flashbang]

@Michael~32/0.2mm is rated at least 6 Amp. If the Amazon 50Mtr reel is £15.19 Not a bad price, but Switch Electronics the seller (who I have used) are also selling the same reels on eBay for £13.79 post free!

https://www.ebay.co.uk/itm/254436601894?hash=item3b3d9a7026:g:VC8AAOSwGbhd396m

You may also like to consider using Wago 221 connector blocks (Toolstation and Screwfix and many electrical wholesalers stock them in the UK) Sold in 2, 3 or 5 way connections. Simply strip the wire end, raise the lever on the 221 and insert wire and press lever down to clip in place and lock the wire. Accept wires mostly used in model railway wiring - 7/0.2mm through to 50/0.25mm and larger. No cutting of insulation or damage to internal wire due to insulation displacement as with Scotchlok and no worrying about getting the right size of connector as needed with Scotchlok connectors! Wago allows two (or more) wires to be stripped and twisted together and then inserted into one terminal, especially the smaller sizes of wires.

[Fishmanoz]

Some pondering to put track and track buses in a little context, particularly given Colin’s earlier post that he is using successfully very lightweight bus wiring, way under the recommended gauges mentioned here, and in the track bus links in the sticky on the General forum:

Your track and track bus operate in parallel with the total current shared between the two. The assumption made for design of the bus is that it must be capable of carrying all of the current.

You can test your system with the “coin test” - place a coin across your track both near the controller and at the furthest point from the controller and your controller should overload immediately. When it does, it proves the system under maximum current fault conditions. If it doesn’t then the system must be high resistance under fault conditions meaning the system cannot carry fault current adequately.

In practice though, particularly for newer layouts, the track will be low resistance when the fishplates are new, untarnished and tightly fitted. Then if one or two fishplates are getting to higher resistance as they age, they are bypassed by the droppers and bus connections either side of them. These loops are short so will be adequate with the lighter gauge wire usually employed for droppers. The short bus run between adjacent droppers will also work with a much lighter gauge than needed for the full bus run.

However, as the layout ages and fishplates tarnish and loosen, the track resistance increases and most of the current will be carried by the bus. Under such conditions, if the gauge of the track bus is too light, it will fail the coin test.

What does this tell us - bus design inadequacies may not show up in the short term as the track can compensate for it while all the fishplates are new, untarnished and tightly fitting. However in the longer term, this may not be the case and it is best to design your bus to meet the design principles that have been well-articulated here over many posts.