Is there a noticeable decrease in resolution of sampled data by using a 50A CT on a 20A circuit? Would I be better off with a 20A CT, or does it not really make any difference?
The accuracy of the 50A is fine.
I must admit I was very worried about this too, but after reading several comments by overeasy on this site I took the plunge and got some 50A CTs with my order, most of the circuits I will monitor would max out below 20A.
I just finished a bench testing session after receiving it and was amazed how accurately it reads a load as little as 50W through the 50A CT that is capable of measuring 12kW at full current capacity, it is as accurate as I can cross check with my meter and matches the readings from a small commercial power meter that I have also!
It does defy what common sense tells you about matching the sensor size to what you are measuring, but i suspect its due to fact that its all transformer based as well as very accurate ADC in the IotaWatt hardware, but whatever it works way beyond my expectations!