Current sensor

I was wondering why more people aren’t using the Allegro current sensors. They are a lot easier to use than a current transformer, they are calibrated and isolated. The only downside that I can see is that you can’t just run an insulated wire through them, you have to connect up their terminals to the line. But they come in 100A, 150A and 200A models.

Allegro also do much smaller rated sensors e.g. 5A, 20A, 30A and 40A etc but as you have pointed out you have to connect up the terminals. Therefore they are less user friendly than a spilt core sensor.

If the main incoming cables belong to your energy supplier, and the terminal box or meter is sealed, as is normally the case, then you cannot, either for safety or regulatory reasons, break into that cable. You would be putting yourself, your family and your property in danger, and risking a big bill from your energy company for putting it back as it was.

What fault current can those devices handle, and how do they perform if there is (say) a lightning strike onto overhead lines serving you? Have you thought about that sort of thing?

Exactly. They are not easier to use. The split-core c.t. can be installed anywhere by anyone, even if they are not qualified to work on live lines, or even by those who don’t have any electrical qualifications provided they don’t fall into the trap of thinking they know what they’re doing, and instead accept and follow advice.

Is that always the case? Presumably the main feed will be behind the ECU for some people and presumably it requires a qualified electrician to open up the ECU.

Not in the UK - the meter tails are almost always visible and accessible. Regulations vary around the world, so always check what’s acceptable where you are.
And if it’s the case that only a qualified person can look at the cables, can you imagine them wiring in a home-brew Allegro sensor that hasn’t been packaged and certified by their particular regulator? Some would probably find reasons not to, even if it was!

I wasn’t thinking by the meter but by the ECU with the trip fuses on the DIN rail. The ones I have seen in the UK are “sealed” units and only normally accessed by electricians, no?

I installed my consumer unit myself, but then I’m a chartered electrical engineer. And I’ve never seen a sealed consumer unit, nor one with the ability to be sealed.

Not literally sealed but the back panel is screwed closed unlike the front panel which simply swings open.