What connections for 16/0.2mm droppers?

[Lacathedrale]

I'm looking to get wiring supplies so when my baseboards arrive, I'm able to get started sooner rather than later. The only layouts I've built in recent memory have been DCC, but this one will be for now DC.

 

I am planning on using 16/0.2mm droppers no longer than about a foot each*, into a terminal block of sorts. My main question is what kind of connectors/terminal strip should I be using for the 16/0.2mm wire? It seems that it's just on the edge of being able to use crimp connectors, and normal terminal strips don't work with wire that small. Any ideas?

 

* It is my understanding that 16/0.2mm can handle up to about 1.5A and this should be sufficient for any modern DCC sound locomotive if I change to DCC in future.

 

Many thanks,

William

[Harlequin]

I found these (these kinds of connectors, not these specifically) to be very useful:

https://www.amazon.co.uk/HSeaMall-12Position-Terminal-Double-Barrier/dp/B076CNTB76/ref=asc_df_B076CNTB76

 

They come with red and black colour-coded forked "busbars" to connect multiple droppers together (VERY useful for model railways!), each terminal can accept a different gauge of wire and the terminals all have clamping washers so the wire is grasped without being chewed up.

 

Also Wago 221 connectors are quite neat and can handle 0.14 to 6 mm² wires. They are great for quick connection changes but they do need to be held in a box - they have no means of being fixed to anything themselves (except maybe by glueing?) The boxes can be a bit chunky.

 

Edited July 21, 2022 by Harlequin
Simplified URL

[Gilbert]

34 minutes ago, Harlequin said:

I found these (these kinds of connectors, not these specifically) to be very useful:

https://www.amazon.co.uk/HSeaMall-12Position-Terminal-Double-Barrier/dp/B076CNTB76/ref=asc_df_B076CNTB76

 

They come with red and black colour-coded forked "busbars" to connect multiple droppers together (VERY useful for model railways!), each terminal can accept a different gauge of wire and the terminals all have clamping washers so the wire is grasped without being chewed up.

 

 

and the busbars can be snipped to increase flexibility.

Chris

[Miss Prism]

RS Stock No: 433-781

 

[Gordon A]

Why not solder your connections?

 

[Pete the Elaner]

5 hours ago, Lacathedrale said:

I'm looking to get wiring supplies so when my baseboards arrive, I'm able to get started sooner rather than later. The only layouts I've built in recent memory have been DCC, but this one will be for now DC.

 

I am planning on using 16/0.2mm droppers no longer than about a foot each*, into a terminal block of sorts. My main question is what kind of connectors/terminal strip should I be using for the 16/0.2mm wire? It seems that it's just on the edge of being able to use crimp connectors, and normal terminal strips don't work with wire that small. Any ideas?

 

* It is my understanding that 16/0.2mm can handle up to about 1.5A and this should be sufficient for any modern DCC sound locomotive if I change to DCC in future.

 

Many thanks,

William

 

According to the item data on Rapid's website, 16/0.2 is rated at 4A.

As far as current carrying wire is concerned, bigger is better because all wire has resistance & the bigger the wire, the lower the resistance & zero is not achievable (apart from superconductors, which nobody will have on a layout).

[Lacathedrale]

4 hours ago, Harlequin said:

I found these (these kinds of connectors, not these specifically) to be very useful:

https://www.amazon.co.uk/HSeaMall-12Position-Terminal-Double-Barrier/dp/B076CNTB76/ref=asc_df_B076CNTB76

 

They come with red and black colour-coded forked "busbars" to connect multiple droppers together (VERY useful for model railways!), each terminal can accept a different gauge of wire and the terminals all have clamping washers so the wire is grasped without being chewed up.

 

Also Wago 221 connectors are quite neat and can handle 0.14 to 6 mm² wires. They are great for quick connection changes but they do need to be held in a box - they have no means of being fixed to anything themselves (except maybe by glueing?) The boxes can be a bit chunky.

 

 

I had considered these, but the smallest terminal block connectors only go down to 20 gauge wire, and 16/0.2mm is 22 gauge - do you think this will work? 

 

@Gilbert @Miss Prism - I figured soldering underneath a baseboard would be unpleasant, but I guess they ARE technically movable baseboards.

[Dagworth]

I'm going to stick my neck out and say that 16/0,2 droppers is massively overkill. 7/0,2 is more than adequate. Continuous current rating of 7/0.2 is 2 amps (source Eileen's Emporium website) https://www.eileensemporium.com/materials-for-modellers/product/p7-0-2mm-electrical-wire/category_pathway-4090

 

Reasons: Firstly almost everywhere current will have more than one dropper as a path to the loco/short circuit.

Secondly if you are looking at continuous current draw then individual droppers don't have to carry current for very long as the train will have moved on to another dropper long long before there is any risk of heat build up. If you are drawing more than 2 amps continuously on a single dropper you have a much larger problem than droppers to look at!

Thirdly 16/0.2 is more difficult to solder to rail, and to hide.

Fourthly look at the wires on the pick-ups and decoders, they are a lot smaller than 7/0.2 let alone anything larger

 

If you doubt the short term current carrying capability of 7/0.2 then try shorting out your DCC system (like the coin test but more direct) by touching each end of a 10ft length of 7/0.2 across the output terminals, your DCC system will cut out, proving that the wire can carry the current sufficient to trip the system in case of an accidental short.

 

7/0.2 resistance is 76.4 ohms per kilometer, you're talking about droppers that are 30cm long, the resistance will barely be measurable at that length. https://www.canford.co.uk/TechZone/Article/MetricAWGWireSizeEquivalents

 

Andi

Edited July 21, 2022 by Dagworth

[Harlequin]

56 minutes ago, Lacathedrale said:

 

I had considered these, but the smallest terminal block connectors only go down to 20 gauge wire, and 16/0.2mm is 22 gauge - do you think this will work? 

 

I don't see why not because the gap between the parallel clamping plates will ultimately reduce to zero - so any wire you put between them will be securely held.

(My droppers are solid core 0.55mm diameter, BTW.)

You could just buy some double barrier terminals to assess. No great loss if they aren't suitable.

 

Edited July 21, 2022 by Harlequin

[Miss Prism]

45 minutes ago, Lacathedrale said:

@Gilbert @Miss Prism - I figured soldering underneath a baseboard would be unpleasant, but I guess they ARE technically movable baseboards.

 

A lot easier when they are on their side. (Note the clamp bottom left!)

http://www.clag.org.uk/pics/somersham/somersham-wiring01.jpg

 

 

[adriank]

Have a look at Brimal. They make a wide range of reasonably priced connectors designed for model railway wiring.

 

They have helpful documentation on site and provide excellent service.
 

Adrian

[Gilbert]

9 hours ago, Lacathedrale said:

 

I had considered these, but the smallest terminal block connectors only go down to 20 gauge wire, and 16/0.2mm is 22 gauge - do you think this will work? 

 

@Gilbert @Miss Prism - I figured soldering underneath a baseboard would be unpleasant, but I guess they ARE technically movable baseboards.

Hi - those blocks don't require any soldering

Chris

[Wheatley]

If the connector is marginally too small for the wires, fold the ends over and resolder before you screw it into the connector. 

 

I've used the RS strips linked to by Miss Prism for almost everything on DC layouts for the last 30 years, and 3A or 5A 'chock block'  connectors where it needs to be removable but not so frequently that it's worth wiring aa plug and socket in. All my point motors, foe example, are wired up via these, so I can swap motors out easily without firing up the soldering iron:

 

 https://www.smallscalelights.co.uk/product/screw_terminal_connector_blocks

[peterfgf]

I used Cesfonjer or Wago-type lever clamp connectors attached to the underside of the baseboard by hot-glue.  I found they provide a very positive and quickly made connection.

Peterfgf.

[WIMorrison]

'Chocolate Blocks' or connector strip are available very cheaply from Screwfix and Toolstation - a lot more cheaply than model railway shops 😉

3A 12-Terminal Terminal Strips 10 Pack | Terminal Strips & Blocks | Screwfix.com

 

Connector Strip 3A | Toolstation

 

 

[Lacathedrale]

Thanks all for the tips!

[Wheatley]

Screwfix is actually where I get them from, it never occurred to me to look on their website for the pic ! 

[AndyID]

On 21/07/2022 at 14:45, Dagworth said:

I'm going to stick my neck out and say that 16/0,2 droppers is massively overkill. 7/0,2 is more than adequate. Continuous current rating of 7/0.2 is 2 amps (source Eileen's Emporium website) https://www.eileensemporium.com/materials-for-modellers/product/p7-0-2mm-electrical-wire/category_pathway-4090

 

Reasons: Firstly almost everywhere current will have more than one dropper as a path to the loco/short circuit.

Secondly if you are looking at continuous current draw then individual droppers don't have to carry current for very long as the train will have moved on to another dropper long long before there is any risk of heat build up. If you are drawing more than 2 amps continuously on a single dropper you have a much larger problem than droppers to look at!

Thirdly 16/0.2 is more difficult to solder to rail, and to hide.

Fourthly look at the wires on the pick-ups and decoders, they are a lot smaller than 7/0.2 let alone anything larger

 

If you doubt the short term current carrying capability of 7/0.2 then try shorting out your DCC system (like the coin test but more direct) by touching each end of a 10ft length of 7/0.2 across the output terminals, your DCC system will cut out, proving that the wire can carry the current sufficient to trip the system in case of an accidental short.

 

7/0.2 resistance is 76.4 ohms per kilometer, you're talking about droppers that are 30cm long, the resistance will barely be measurable at that length. https://www.canford.co.uk/TechZone/Article/MetricAWGWireSizeEquivalents

 

Andi

 

Yes, the "fusing current" (the current at which the conductor will actually melt) for 7/0.2 copper wire (equivalent to 24 AWG) is greater than 29 amps 😀

 

Wire current ratings are more to do with heat affecting the insulation over time. Foot long droppers in 7/0.2 will not be a problem at all. You could even use smaller wire but it's probably not worth the aggravation.

 

I find it easier to solder a short length of non-insulated solid copper wire to the end of the flexible wire and poke it through a small hole in the baseboard to solder to the rail. I use solid 24 AWG for that. It is 0.5 mm diameter.

[melmerby]

2 hours ago, AndyID said:

 

Yes, the "fusing current" (the current at which the conductor will actually melt) for 7/0.2 copper wire (equivalent to 24 AWG) is greater than 29 amps 😀

 

 

7/0.2, the 0.2 is cross sectional area. 7 x 0.2 = 1.4mm total CSA which is pretty close to 1.5mm mains cable which can carry a continuous current of 14.5A in the worst case scenario.

 

Ignore, it's total twaddle!

Edited July 23, 2022 by melmerby

[Crosland]

43 minutes ago, AndyID said:

 

Yes, the "fusing current" (the current at which the conductor will actually melt) for 7/0.2 copper wire (equivalent to 24 AWG) is greater than 29 amps 😀

 

Wire current ratings are more to do with heat affecting the insulation over time. Foot long droppers in 7/0.2 will not be a problem at all. You could even use smaller wire but it's probably not worth the aggravation.

 

I remember one poster on another forum who insisted using 7/0.2 (or it might have been 1/0.7) for DCC droppers through the baseboard would cause layouts to catch fire 🤣

Edited July 23, 2022 by Crosland

[AndyID]

4 minutes ago, melmerby said:

7/0.2, the 0.2 is cross sectional area. 7 x 0.2 = 1.4mm total CSA which is pretty close to 1.5mm mains cable which can carry a continuous current of 14.5A in the worst case scenario.

 

Alas no 😀.

 

It's 7 0.2 mm in diameter wires. Each wire has a CSA of 0.31 sq mm for total CSA of 2.17 sq mm.

 

Also, mains cable is all about how the heat produced as a result of the resistance loss affects the insulation. That means it has to deal with the current out and the current back which doubles the heat produced in a two wire cable. It gets worse when a lot of cables are bundled into a single conduit and there are various de-rating specs for how to deal with that.

[AndyID]

32 minutes ago, AndyID said:

 

Alas no 😀.

 

It's 7 0.2 mm in diameter wires. Each wire has a CSA of 0.31 sq mm for total CSA of 2.17 sq mm.

 

Also, mains cable is all about how the heat produced as a result of the resistance loss affects the insulation. That means it has to deal with the current out and the current back which doubles the heat produced in a two wire cable. It gets worse when a lot of cables are bundled into a single conduit and there are various de-rating specs for how to deal with that.

 

 I'll leave that up there because it's WRONG!

 

The CSA of each wire in a 7/0.2 cable is 0.03 sq mm. That means the total CSA is 0.22 sq mm which is the same as a solid copper conductor of 0.5 mm diameter which has a fusing current greater than 29 amperes.

[melmerby]

1 hour ago, melmerby said:

7/0.2, the 0.2 is cross sectional area. 7 x 0.2 = 1.4mm total CSA which is pretty close to 1.5mm mains cable which can carry a continuous current of 14.5A in the worst case scenario.

 

Oh Dear.

I don't know where I got that from.☹️

 

(Even what I thought was my 7/0.2 wire actually turns out to be 16/0.2! (It's what I used for droppers, mainly because of the mechanical strength)

 

The only correct bit was the 1.5mm mains cable which I quoted for T&E bunched in a conduit, the worse case scenario!

A single 1.5mm T&E cable clipped back has somewhat greater current carrying capacity,

 

 

Edited July 23, 2022 by melmerby
typo

[DCB]

For strict prototype authenticity use a a nut and bolt and connect the rail ends...

[melmerby]

 

What's wrong with just soldering the wire?🙂

?