How many droppers from a single bus connection?

[Sir TophamHatt]

Not sure if this is really worth asking but how many droppers wires would you put together connecting to one bus wire connector?

 

So I use the little blue clips to connect dropper wires to my bus wire. However, when it comes to point work, I try and connect all bits of the point to a bus wire.

 

This means, some little blue clips have three dropper wired coming out of them connecting to three different sections of track. Some have two. Most have just one.

 

It's not all the time but it does save between 10 and 20 extra blue clips connecting to the bus wire.

 

Just want to make sure I'm not risking a huge amount by doing this.

 

Thanks

[gordon s]

Just to clarify.  When you say little blue clips, do you mean something like this as there are many types of connector?  On this one the wires go in each end, you close the clip over and press it down with a pair of pliers.

 

 

Edit:  Can I also ask what wire size you are using?  Stranded or solid?

 

This table may help.

 

 

 

These connectors are called Insulation Displacement Connectors or IDC for short.

 

They are also known as Scotchlok IDC connectors.

 

In simple terms you have a metal blade with two slots.  The width of the slot is specifically designed to suit quite a small range of wire sizes.  It works on the principle of the blade cutting through the insulation and making contact with the bare wire.  They will take solid or stranded wire.

 

It will look something like this with the red indicating the conductor.  In the process the conductor is squeezed and will typically take on an oval shape.

 

 

They are deigned to take two wires only, one of which may be a through wire.

 

The Scotchlok connectors come in two sizes.  The blue one accommodates 16-18AWG and the red one 18-22AWG.

 

As you can see the from the chart above the common wire sizes often used in model railway electrics are 7/0.2 or 16/0.2 which are 24/23 AWG and 20AWG respectively.  

 

What is often not appreciated is that in order for the connector to perform to its specification, it's very important to use the correct wire/connector combination.

 

If you are using a wire too large for the slot, then conductors of a stranded wire will be cut and you will reduce its current carrying capability. If the wire is to small for the slot, then the electrical contact will be impaired and long term reliability will suffer.

 

Here is the official spec for the blue Scotchlok connector.

 

http://multimedia.3m.com/mws/media/41207O/3m-scotchlok-id-electrical-tap-connector-560b.pdf

 

 

 

 

Edited January 12, 2018 by gordon s

[Sir TophamHatt]

Sorry, yes, a suitcase type clip, or crimp blade splice as rs electronics calls them. Although weirdly the part number doesn't exist anymore. It was 31-0190, but looks like these:

 

I'm using stranded wire from express models; 0.2mm. http://www.expressmodels.co.uk/acatalog/DCC_No_Solder_Power_Bus_Kit.html

 

I've done a couple of doubles at the back section, which seems to be okay. Not that I'd want to, but four wires won't fit in the crimp blade anyway. Three struggles.

Edited January 12, 2018 by anotheruser

[Pete the Elaner]

All wire has resistance so the aim is to keep this as low as possible. Bigger diameter wire has lower resistance so iIf you can use 15A wire, then it won't do any harm. This may be OTT  & you won't always be able to fit it in your connectors.

The more wire you try to pack into a connector, the more likely you are to have a bad connection in there. Bad connection = our old enemy, resistance.

[gordon s]

I'm guessing then it's this one and suitable for 14-18 AWG

 

The same rules will apply.  Now here's the rub. I'm guessing that as they are easy to use, they get abused.  Wrong wire size and multiple wires in the same slot is outside their spec, so don't be surprised if you find connectors failing or intermittent issues.

 

When all said and done they are cheap compared to other methods, so why sacrifice reliability to save a bob or two?

 

http://solutions.3m.co.uk/wps/portal/3M/en_GB/ElectricalMkts/ElectricalSupplies/products/scotchlok-wire-connectors/scotchlok-electrical-idc-wire-connectors/scotchlok-952-t-tap-disconnect/

Edited January 12, 2018 by gordon s

[Enterprisingwestern]

I have to admit to using Scotchloks, although they cause a sucking in of breath through the teeth in some quarters.

They are cheap enough to use 1 per dropper if you have enough bus wire lemgth to do so, I would think trying to cram 2 wires in might be asking for trouble though.

 

Mike.

[ROSSPOP]

Hi

 

I have used `suitcase` connectors exclusively on my recent O Gauge layout with total success.

 

DO NOT OVERLOAD THE CONNECTORS WITH     MULTIPLE DROPPER WIRES YOU WILL REGRET BIG TIME.

 

 

ONE DROPPER WIRE PER CONNECTOR

 

Regards

 

John

 

PS.... so that`s a NO then......

Edited January 12, 2018 by ROSSPOP

[gordon s]

There are other alternatives...

 

These are great, strip the wire, lift the lever, insert wire, close the lever.  They will accept a much wider range of wire sizes and come in two, three and 5 way and you can use them over and over.  The only down side is that they don't have a through connection.  It simply commons all the wires together.  I've used them and never had a problem.

 

 

....and this the old way. 

 

You can put as many wires in these as you want.  One slot for the bus wire and use the others to your hearts content.

 

Edited January 12, 2018 by gordon s

[Pete the Elaner]

I drive a copper pin into a block of wood (could be the baseboard but I use a small section of softwood) & use the pin as a mounting point, soldering the bus & droppers to each pin. This also binds the lot to the board too, helping to prevent sagging.

[DCB]

These evil little clips should be banned.   They are frequently used in car bodgery and work loose and make intermittent contact. Total waste of time.

Twist the wires together  solder them and insulate with heat shrink.   Use a section switch for every six or more yards of track if you want to stand any chance of finding the inevitable short.

[gordon s]

Having worked for connector companies for 30 odd years, the principle of IDC works well. The problem as always is lack of understanding by the end user. The use of the correct wire gauge with the correct connector is perfectly reliable .....at least it was when I was in the business....:-)

[ROSSPOP]

These evil little clips should be banned.   They are frequently used in car bodgery and work loose and make intermittent contact. Total waste of time.

Twist the wires together  solder them and insulate with heat shrink.   Use a section switch for every six or more yards of track if you want to stand any chance of finding the inevitable short.

 

Total Twaddle.................

[Enterprisingwestern]

These evil little clips should be banned.   They are frequently used in car bodgery and work loose and make intermittent contact. Total waste of time.

Twist the wires together  solder them and insulate with heat shrink.   Use a section switch for every six or more yards of track if you want to stand any chance of finding the inevitable short.

 

So how do you conveniently and easily strip a section of insulation out of a run of bus cable every few mm and twist it to make a connection?

 

Mike.

[Guest]

Hmm. Although I'm always on the lookout for new ideas, I haven't found anything more convenient than those evil little blue and red clips. Evil they may be, but I figure I'll probably go to Hell anyway. I don't like heights and I prefer the heat.

Incidentally, I can understand how you can easily strip a centimetre or two from the bus wire, twist the dropper wire around it and then solder. How, may I ask, do you then get a short length of heat-shrink tube around the whole thing if the bus wire is already in place?

 

Edited for typo.

Edited January 13, 2018 by Pete 75C

[Nigelcliffe]

So how do you conveniently and easily strip a section of insulation out of a run of bus cable every few mm and twist it to make a connection?

 

Mike.

 

Stripping back insulation in middle of a wire is simple, a set of these does it by breaking the insulation and pushing it back along the wire.  Exposes about half an inch of bare wire. 

I'm sure other tools can do the same job.

 

https://www.rapidonline.com/ck-tools-495001-automatic-wire-stripper-85-0002

 

( They're also effective for removing insulation at end of wires, pulling the outer core off multi-cored cables, etc.. ).

 

 

 

- Nigel

[Crosland]

These evil little clips should be banned.   They are frequently used in car bodgery and work loose and make intermittent contact. Total waste of time.

Twist the wires together  solder them and insulate with heat shrink.   Use a section switch for every six or more yards of track if you want to stand any chance of finding the inevitable short.

 

When used as intended they are perfectly reliable. When fitted in harsh environments (e.g. under the bonnet fo a car) by poorly paid grease monkeys do they cause problems.

 

They are perfectly acceptable for DCC when the correct wire sizes are matched with the correct connectors.

[34theletterbetweenB&D]

So how do you conveniently and easily strip a section of insulation out of a run of bus cable every few mm and twist it to make a connection?.

I don't! Bare wire as the bus is so much easier, solder on all connections. Always done this for common return on DC, and having a pair as bus wires is a natural extension.This works beautifully for a permanent layout, not recommended for exhibition/portable.

[WIMorrison]

How do you put a twist into the bus pair if they are uninsulated?

[tractor_37260]

How do you put a twist into the bus pair if they are uninsulated?

 

Why would anyone use a  "non-insulated" bare wire for a bus ?  A cheap source for a main bus cable is used/secondhand mains T&E cable, strip the outer casing and use the insulated cores of live and neutral, these can then be twisted if necessary. Using a tool similar to the one shown above, small parts of the insulation can be removed and the droppers twisted around and then soldered.

 

https://www.rapidonline.com/ck-tools-495001-automatic-wire-stripper-85-0002

[WIMorrison]

I don't! Bare wire as the bus is so much easier, solder on all connections. Always done this for common return on DC, and having a pair as bus wires is a natural extension.This works beautifully for a permanent layout, not recommended for exhibition/portable.

 

 

Why would anyone use a  "non-insulated" bare wire for a bus ?  A cheap source for a main bus cable is used/secondhand mains T&E cable, strip the outer casing and use the insulated cores of live and neutral, these can then be twisted if necessary. Using a tool similar to the one shown above, small parts of the insulation can be removed and the droppers twisted around and then soldered.

 

https://www.rapidonline.com/ck-tools-495001-automatic-wire-stripper-85-0002

 

I don't use bare wire nor am I suggesting that is what is used - look at the post prior to mine (quoted above to help) and you will see what I was replying to

[Enterprisingwestern]

Stripping back insulation in middle of a wire is simple, a set of these does it by breaking the insulation and pushing it back along the wire.  Exposes about half an inch of bare wire. 

I'm sure other tools can do the same job.

 

https://www.rapidonline.com/ck-tools-495001-automatic-wire-stripper-85-0002

 

( They're also effective for removing insulation at end of wires, pulling the outer core off multi-cored cables, etc.. ).

 

 

 

- Nigel

 

Conveniently?

 

Mike.

[Butler Henderson]

Seen quite a few exhibition layouts with bare bus wires. Mine did have them but on rebuilding it for home use I have replaced them on one board, and not used such on the new boards. I slid large single chocolate block connectors along the bare wires into which droppers etc could be fastened.

 

The new bus wires are 32/0/2 wire twisted together between quick release connectors from Tool Station (or Screwfix but usually dearer) - not exactly the neatest as you have to split the bus wires apart as the connectors are single pole but great in fault finding as its simply a case of flipping the lever and pulling out a wire out as necessary.

EDIT and stick in place with No More Nails tape.

 

i.e.https://www.toolstation.com/shop/Electrical/d190/Cable+Management/sd2460/In-Sure+Lever+Wire+Connector/p12527

Edited January 13, 2018 by Butler Henderson

[Ron Ron Ron]

Just a tip if using the metal earth blocks as junction connectors for the Power Bus and droppers.

It might be advisable to put these into a connector box cover or box, to prevent the risk of shorts or damage if the bare metal junction block comes into contact with any other wires, or metal objects.

 

Example here

 

    

[newbryford]

Stripping back insulation in middle of a wire is simple, a set of these does it by breaking the insulation and pushing it back along the wire.  Exposes about half an inch of bare wire. 

I'm sure other tools can do the same job.

 

https://www.rapidonline.com/ck-tools-495001-automatic-wire-stripper-85-0002

 

( They're also effective for removing insulation at end of wires, pulling the outer core off multi-cored cables, etc.. ).

 

 

 

- Nigel

 

Strippers like that are brilliant for adding extra droppers.

Having just wired a layout with a DCC bus previously installed by someone else before all the track was laid. It didn't have enough connections for droppers.

I used a set from DCC Concepts https://www.dccconcepts.com/product/high-quality-power-bus-strippers/ along with their bus wire tags to add droppers.

They work out a little bit cheaper than the Rapid versions when the VAT is included

 

I'm quite happy using them from 1.0mm to 3,5mm wire.If you untwist the bus wire for about 75mm and line them up properly, you can even strip back both bus wires at once.

 

I have the point motors to add and I know I will need more DCC connections -the strippers will be called into action again soon.

 

Cheers,

Mick

Edited January 16, 2018 by newbryford

[newbryford]

Conveniently?

 

Mike.

 

Yes, very.

I've just put in 200 plus droppers and DCC wiring on a big layout.

 

Cheers,

Mick