# Getting started in the USA **URL:** \ **Category:** emonPi\ **Created:** [21 March 2021 18:10 UTC](https://community.openenergymonitor.org/t/getting-started-in-the-usa/17270 "2021-03-21T18:10:09Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![danb35](https://community.openenergymonitor.org/letter_avatar_proxy/v4/letter/d/dfb087/32.png) [@danb35](https://community.openenergymonitor.org/u/danb35)\ **Post date:** [21 March 2021 18:10 UTC](https://community.openenergymonitor.org/t/getting-started-in-the-usa/17270/1 "2021-03-21T18:10:10Z")
I’m wanting to start monitoring my home’s energy usage in preparation for going solar, and the emonPi sounds like it should handle what I’m wanting to do. One thing I’m not 100% clear on from the product/software pages I’ve seen so far: will this show **peak** power usage? IOW, can I pull a number for the highest energy usage over the past day/week/month/year? If I only wanted monthly totals, I can get those from my past electric bills or online from my utility, but I’d like if possible to size the system to cover the peak load, and that sort of history doesn’t answer that question. Second question: I’ve been over the “Use in North America” page, and understand (as I’d suspected) that I need two CTs. My home has 200-amp service, and I think that would mean that I couldn’t use the default 100A CTs; I’d rather need to use these: > **[200A max clip-on current sensor CT](https://shop.openenergymonitor.com/200a-max-clip-on-current-sensor-ct/)** > > Open-source hardware tools for energy monitoring and visualisation Is that correct? Are the other changes I’d need to make? ---
**Author:** ![Robert.Wall](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/robert.wall/32/38246_2.png) [@Robert.Wall](https://community.openenergymonitor.org/u/Robert.Wall)\ **Post date:** [21 March 2021 18:20 UTC](https://community.openenergymonitor.org/t/getting-started-in-the-usa/17270/2 "2021-03-21T18:20:14Z")
Welcome, Dan, to OEM. > [@danb35](#): > > will this show **peak** power usage? IOW, can I pull a number for the highest energy usage over the past day/week/month/year? That isn’t, as far as I know, a feature of the software (but I’m not an expert in that area), but the software (emonCMS) will record the power at 10 s intervals, so you should see not only the peak, but the full usage pattern too. > [@danb35](#): > > I couldn’t use the default 100A CTs; The limiting factor will almost certainly be the size of your service entrance wires - the “standard” c.t. can only accept a cable less than ½" diameter. This is well worth reading: > [@US 200 Amp Service explained or Do I need a 200 Amp CT?](https://community.openenergymonitor.org/t/us-200-amp-service-explained-or-do-i-need-a-200-amp-ct/4219): > > A common question is “I have 200 Amp service, do I need a 200 Amp CT?” The answer is most likely no. Unless you have a very large house, a 100 Amp CT would be a better choice. (Large houses, typically have 320 or 400 Amp service and may actually need a 200 Amp CT, but this article addresses 200 Amp service installations) So what does the term 200 Amp service refer to? Simply put, it means the weakest link in your Service Entrance Wire, Meter Base, Meter, Main Breaker, Load Center (circuit b… ---
**Author:** ![danb35](https://community.openenergymonitor.org/letter_avatar_proxy/v4/letter/d/dfb087/32.png) [@danb35](https://community.openenergymonitor.org/u/danb35)\ **Post date:** [21 March 2021 19:43 UTC](https://community.openenergymonitor.org/t/getting-started-in-the-usa/17270/3 "2021-03-21T19:43:47Z")
Thanks for the informative link–it had me hopeful that I’d be able to use the smaller CTs. So I pulled the cover off my main load center and measured the input wires–0.59" (15mm) diameter. I guess not–back to the larger ones.