4mm plug confusion

Thread Starter


Joined Oct 29, 2017

I have a couple of cheap-ish DMMs. One needed a new pair of test leads so I got some on eBay, but the 4mm plugs didn't fit the sockets on either multimeter. On another occasion I was tempted by a set of test leads with all sorts of fancy tips and clips - same problem. Futhermore, the original test leads aren't interchangeable between my two DMMs. I bought a pair of shrouded 4mm plugs to retrofit to one of the incompatible test lead sets but it seems to be impossible to fit the 4mm pin into the shroud.

Is there no standardisation? Some 4mm plugs are shrouded and some unshrouded. The length of the 4mm pin and the depth of the contact in the socket seem to vary, and in the shrouded ones, the shroud dimensions vary, and some have a safety insulated tip to the pin. The only thing that seems to be fairly standard is a good ol' unshrouded banana plug with a 20mm long pin.

Apart from spending a lot more on a professional grade multimeter with branded test leads, what is one meant to do?