If you struggle with joining wires — such as track feeders to bus wiring — this is for you.
Historically if you want to join one wire in the middle of another (wiretapping) you’d cut a section of outer sheaf off the first wire and then wrap the second wire to the exposed copper and then solder them together.
Where you have lots of track feeder wires to attach to a main bus wire running around a layout this can be time-consuming and frustrating. And, if you accidentally cut through the bus wire while stripping it, well, that’s just annoyance central.
But if you’re new to model railway wiring or perhaps returning after a time away, there’s an alternative that makes connecting two wires together much much easier and far quicker. I’m also surprised by the number of modellers who haven’t come across these and still struggle with soldering.
It’s a little wiring accessory commonly known as a suitcase connector, snap lock connector, Insulation Displacement Connectors / IDCs or scotch locks (Scotchlok is the 3M brand name) and are ideal for single strand wires.
Joining wires with these is simply a matter of placing the two wires to be joined into channels, clamping the lock with a pair of pliers and then folding over the latch to keep it sealed. That’s it It’s a fast, efficient and simple way of joining wires without stripping, crimping or soldering.
This video shows how they work.
You might come across some comments that these have problems and should only be used temporarily. However, this is due to their use in environments exposed to the elements or where the wiring will be moved around a lot such as in the electrical systems of cars and boats. For model railway wiring they seem perfectly okay and more than up to the job.
I also like that they’re available in different colours so can match up with a colour-coding system for the bus wiring and feeder wiring, be aware however that the colour of the connector is related to the size of the wiring so you’ll need to use different gauges of wire for the different colours (thanks to Tom Lawton for the heads up on this point).
You can see these in action in this video on bus and feeder wiring:
The only downside is they’re really for medium gauge wires (14-22 gauge). I use heavier gauge wires for the bus on my DCC N / OO layouts — 16 gauge for the bus and 18 for track feeders — so this hasn’t been a problem. If however, you use smaller gauge wires you might want to test them first. And just in case you’re thinking of using them for other applications, they’re not recommended for normal household wiring.
Did you know, last year MRE (this website) was nominated and went on to win Silver for best website in the British Model Railway Awards. This year, I'm honoured that it's been nominated again! MRE is a labour of love and your vote for it in these awards would really encourage and motivate me to develop the site further, creating more free tips, advice and guides. If you would like to support me, please click here and select your entries in the various classes of entry. If you don't have a preference for a particular category, you can skip that class. The Website of the Year is on the final page, just tick the box next to Model Railway Engineer to support me. Thanks Andy, creator of MRE.
Update: This article originally stated these were available from Maplin etc. Several modellers have contacted me to say they couldn’t find them in Maplin stores so this reference was removed. The original article also didn’t state that the colour of the connectors reflects the size of the wire to be used and there was a typo in the wire gauge I use.Disclaimer: Some links on this page will take you to Amazon or eBay through which you can buy the products mentioned. These links are made under the Amazon and eBay affiliate scheme which means that although the price to you doesn't change I get a small commission on the orders you place. Please see the disclaimer for more details.