Energy use monitor, current transformers.

Not that one specifically, but I have (somewhere) one of these:

Judging by the scale of the jack plug I imagine that one is similar. ... ah, this has dimensions:

Probably doable. Or to tails outside.

Worth having a poke around Openenergymonitor as you might find they already make something to do what you want. Although 16 circuits might get a bit much.

Theo

Ah, well spotted, 57mm long by the looks of it - so quite large... might be able to get them in at an angle - and stagger the height of adjacent ones.

(I quite like that they are fully enclosed and are available in a voltage output version)

I wanted to be able to record each circuit in isolation really (or at least a number of them)...

Although one on the tails may be handy since I have one tall RCBO that there is unlikely to be space to clamp - so calculating that as total - others might do it.

Yup I did have a look at that - they did not have any off the shelf designs that did more than a small number of channels.

You could try

You could wind your own current pickup on individual wires and calibrate.

The ration of turns would be key. Hardly any need to calibrate. The concerns would be the core material, saturation, leakage and bandwidth to catch a spiky waveform.

You might find Rogowski coils convenient.

They were one of the reasons given for the inaccurate readings by some meters in that Dutch university study a few years ago ...

Maybe the affected meters weren't using them properly?