Optimal CT Locations


About to dip my toes into the water so first post. I have looked at my electrical cabinet and I have space to place CTs in a few locations but I am seeking advice on optimal locations. My only future plans are the addition of more solar - probably single phase as I am limited on how much I can put back into the grid based on a limit per phase. 1 phase currently maxed out other 2 not used.

My Power System: 3 phase power in - all large single colour cables (cream). This comes into 3 x 80amp fuses then into smart meter . 2 phases to master switch. 1 phase to active link (solar single phase added here) then to master switch. Off peak Hot water system is taken from one of the 80amp fuses to its own smart meter/switch (this seemed very odd to me as it would mean I can turn the master switch off but still have power to the Off Peak HWS - assuming that it is so different costing for hot water can be calculated but never realized this before)

From Master On/Off. 3 phases go to various circuits to power the house (need to figure out what does what as lots of changes over the years) but basically 10 different circuits. 1 circuit breaker 50 amps going to back shed (single phase) all the rest 32 amp and under.

From Master On/Off. 3 phases to circuit breaker for 3 phase AC. 32 Amp breaker. Then to AC unit. These cables are blue/red/white so hoping to trace them back to input from street to align cable colours - not sure if this is necessary though.

From Solar Inverter (Single Phase) into 32 amp breaker to Smart Meter and then to join up with Active Link.

Hot Water System (OFF PEAK) - from 80amp fuse to smart meter to smart switch to circuit breaker to HWS.

So power in. Where is the optimal location. Before Fuses where nothing is split off (was my original thought but as HWS is charged at different rate I would be unable to do costings accurately)? After fuses where I have power being taken for one phase to the HWS (Thinking here)? After smart meter & before master switch .

Solar. Where it comes into the box - before the circuit breaker (my thought) or after smart meter and before where it joins into active link?

AC. After the master switch (my thought) & before circuit breaker or after circuit breaker?

Individual Circuits wherever you can fit them as required once I have traced down what they have done with the spread of the 3 phases.

Last question (for now). If you have a 50amp circuit breaker should you use a 100amp CT or is 50amp CT sufficient?

Sorry if I am asking the obvious here (actually typing it out helps the thought process) but I am just getting my head around this as I don’t know if circuit breakers help, hinder or play no part in measurement.

Thought I had better add the reason I am doing this. Trying to figure out my total consumption to plan/decide on how much additional solar I need and how big a battery I might need in the future to meet the household power needs. I know my biggest power usage is AC (only heating) but just how much?

So any advice appreciated.

Sorry, I can’t follow this description of your system. You would do well to construct a line diagram for the purpose of this discussion. Believe me, it will come in handy as you contemplate what is going on and future changes.

50A CT is fine for 50A breaker.

I hope this makes sense. I have put the CT images where I would put them

Those locations look OK.

Doesn’t matter as long as you are measuring the solar and HW individually. You can always create an output that subtracts the HW from the main if the CT is before the split.

Either way.

Either way.