I am trying to setup whole house monitoring on a friend’s house. They have a huge house with a 400A service (400A disconnect feeding to two 200A panels). Optical Sensor is not an option as the meter is on a pole about 200m away from the house. I have ordered 4 Wattcore WC3 200A:100mA CTs. Because I have so many lines to watch I am hoping to set them up as described in 5b of EmonTx-in-North-America (wired in parallel with a common burden using a single input).
If anyone was interested in checking my calculations I would be grateful. I know just enough to get myself into trouble.
So the CTs I have ordered are 200A:100mA and the specs say nothing about turns, but I am going on the assumption the turn ratio is going to be 2000:1
Because I intend to wire two CTs in parallel to measure both legs and save on inputs I know that my burden resister needs to expect double the current. I calculate a SINGLE of these CTs as needing 11 ohms and that two hooked up in parallel should require a 5.5 ohm value for the burden.
I want to have the burden resister hooked up before the jack so that when unplugged it is safe. The EmonPi and EmonTx V3 have a 22 ohm burden resistor. If I were to keep the existing burden resistors in place and just add something to lower total resistance I calculate that I would need a 7 ohm resistor.
Am I on the right track? With this I can use one EmonPi input for the first 200A panel and the second EmonPi input for the second panel for a combined house power. I would then use an EmonTx V3 for measuring consumption on a few other circuits.
With a burden of 7 in this particular configuration it works out to MAX current of 220 each leg. With a burden of 8 in this particular configuration it works out to a MAX primary current of 198A each leg with both legs maxed. I’m inclined to go with an 8 ohm 1W 1% metal film resistor.
Thank you for your time! I’ve been reading and reading for about a month on various topics. I’m just looking for some confirmation that I am on the right track from someone else who has done this.