Hi, I'm hoping someone can help me figure out the best way to install an Emon kwh submeter to monitor electrical usage in my garage. I bought a house with one attached garage and a second detached garage. I want to rent out the house and use the detached garage. I intend to run a couple compressors and use an arc welder, plus it has electric heat and A/C. Bottom line is that I want to rebate the tenant for the electricity I use in the second garage.
My main panel has a double 50-amp breaker that feeds the garage's sub-panel (3 - 6ga in 3/4" rigid pipe). The sub-panel holds up to six breakers and 4 slots are filled with 1-30 amp dual and 2-20 amp breakers. I would like to use the remaining 2 slots for the welder's breaker (50-amp dual).
The submeter is model 1000 for 2-line, 240v, 1-phase, 100 amp. The submeter must have 2 power feeds + neutral and must be powered by the line(phase) being monitored by the corresponding Current Transformers (CTs). The leads for the CTs can be up to 2000 feet long.
I can think of several ways to install the meter :
1) I can pipe in the meter on the house side from the main panel, add 2 15-amp breakers, run 14ga power to the meter (with 1-amp inline fuses), run the lines for the CTs to the main panel and install the CTs at the 50 breaker. Problem is, I want to be able to read the meter without going into the house. I don't think the meter is rated for the outdoors. Also, I don't want to tear up the family room to add the conduit or run it outside the house (a lot of work depending on where I finally put the meter).2) Install the meter in the garage. Take up the last 2 slots in the subpanel with 2-15 amp breakers for the meter, install the Current Transformers in the subpanel and run power and the CT leads to the meter (not good cause then I loose the welder, but easiest). Or, I could upgrade the subpanel with one that has room for more breakers (not good - more work).
I don't think it matters if I install the current transformers in the main panel or the sub-panel. The current is the same in both places. Yes, the voltage drops at the garage but I am billed for watts-used which is the same(?). Probably not a big deal any way, even if it did affect the metering accuracy (