I want to install an electricity usage monitor ("in-home display", IHD) so I can track my home energy consumption. I have seen there are some products, like this Watts Clever which use a sensor over the LED impulse indicator of the digital/"smart" electricity meter, and others like Efergy Engage or Smappee which use current-sensing clamps ("CT clamps") that clip onto the electrical supply wire(s).

I have only a naive familiarity with my home electrical supply. While I know I could install the first type of monitoring product myself (the home is equipped with a digital meter with impulse LED), it is the feature set of the second two (namely online monitoring) that I really want; but I'm not totally sure whether the existing hardware is the right kind for attaching CT clamps to. It's not worth it to me if I'll have to pay for an electrician to come out and do any rewiring to accommodate it.

Here is the layout of my home electrical meter cabinet/breaker box. (I'm in Australia and the supplier is ActewAGL, and I have only mains supply - no solar or self-generation/storage yet.)

electricity cabinet layout

So at the bottom is the row of breaker switches which isolate different parts of the house (not visible in photo: they are numbered according to the laminated sign); and in the upper right is the digital electricity meter that the utility reads to bill me for my consumption (and where I'd attach the impulse sensor for the first kind of monitor previously mentioned).

I'm tempted to think the thick exposed wire in the upper left is the main supply coming into the house and where I'd need to go to attach my CT clamp, but it's strange-looking and I'm not sure. Here's a closeup picture:

closeup of wire

My questions:

  • What's the chunky translucent plastic thing doing? (I'm guessing a main fuse between the main supply and the house, or some kind of filter?)

  • Why two different colours of wire? (I'm guessing red is the supply side before the fuse and blue is the fuse-protected house side?)

  • Can I be confident I don't need an electrician to expose any wires for me/that this is the place for a CT clamp? If so, is there a preferred side of that plastic protrusion (colour of wire) to place the clamp?

1 Answer 1


You're right on the money

Yes, you have indeed found your main fuse in that clear plastic fuseholder. I wouldn't make any guesses about the wire colors, but that's OK, because either side will work for clamping the CT onto it. If you want to double check, simply detach the fuse-section from the fuseholder -- that should kill all power to the house if our theory here is correct.

  • Thanks for confirming my guesswork, looks like I can go buy my new gadget with confidence. Sep 26, 2017 at 1:40

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