Why every toolbox needs a handful of jelly crimps

Regular readers will know that I love Wago lever nuts for making strong, reliable connections to domestic mains voltage wiring. But the other connector I use the most is the jelly crimp. In fact, I used some today to fix some frayed wires on a doorbell.

Jelly crimps are a staple of telecom installation and repair (at least here in the UK). I was introduced to them years ago by an engineer who gave me a few of them, and I’ve been hooked ever since.

Also: How to strip wires like a pro (and my must-have tools)

These connectors come under many different names, but jelly crimps are the most commonly known of them.

The little “jelly” in the name comes from the fact that the ends are wrapped with a dielectric silicone sealant that both adds more insulation and also makes the connection unalterable over time.

It comes in two-way (called UY) or three-way configurations (called UR), depending on whether you want to connect two or three wires together, and it is specifically designed for including solid core copper or aluminum telephone and communication wires.

Also: How to use heat-shrink butt connectors to repair damaged wires

With UY and UR configuration differences, there are different sizes depending on the outside diameter of the wire you connect with the jelly crimp. The regular UR and UY are for thinner 22-26 awg wires with an insulation outer diameter of 1.52mm, while the UY2 and UR2 sizes accommodate thicker 19-26 awg wires with a maximum insulation outer diameter of 2.08 mm.

You can find a lot of different brands out there, and they can be hit and miss, and I’ve seen cheap ones that fall out or don’t contain gel. I have a source in the telecommunications business that keeps me supplied, but if you need to buy it online, I recommend going with the 3M Scotchlok brand.

I find that both methods are the most useful, with a 100 packs of UY and a 100-pack of UY2 enough to satisfy my needs.

They are dead easy to use.

You cut the cable, poke the ends all the way through (no need to strip the insulation), and squeeze the button to cut it and bite the cable.

Also: How to solder: Tools, tips, and tricks to get you started the easy way

That’s easy!

Their primary use is telephone wiring, but I’ve also used them in alarm systems, doorbells, speakers, and other low-voltage applications. These connectors can handle up to 50V, so don’t use them on mains voltage in case someone – possibly you – dies.

The connections are very reliable, and as long as they are not submerged in water, they last for decades (and even submerged ones have a long life, in my experience).

There is one special tool for making a squeeze that you can get for $15. If you do a lot of crimping, this might make sense, but I find that I can use my finger and thumb, or a pair of Knipex mini water pump pliers to do the job.

Did I mention they are incredibly satisfying to “pop”?