I am having a similar issue installing a Fortress duo 21 on a 600 amp service with parallel mains.
Best place I found is accuenergy.com for CTs of all types. I’m sure you know that the CT‘s Fortress uses are a constant 333 mV output. Accu Energy has a good line of those types ready for all sorts of currents and aperture size. I’ve used Accuenergybmetering systems before along with their CT’s and I’ve never had a problem with them. On Mon, Oct 12, 2026 at 5:36 PM William Miller <[email protected]> wrote: > Friends: > > > > I am installing my second Fortress Envy8 inverter and I am encountering > the same problem for the second time: The supplied CTs are too small to > clip around the service-entrance conductors. I contacted Fortress and they > were not much help. They said try Aim Dynamics, without specifying a > product. > > > > The CTs provided are rated at 100 Amp / 100 mA. This means they have a > 1000 to 1 ratio. Is it valid to say I could replace the provided CTS with > any CT that has the same ratio? I have found this to be true when > contemplating DC resistive shunts, like for the Outback FNDC. > > > > Thanks in advance. > > > > William Miller > > > > William Miller > > Miller Solar > > www.millersolar.com > > CA License C-10 77398 > > > _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > > List Address: [email protected] > > Change listserver email address & settings: > > https://lists.re-wrenches.org/mailman/options/re-wrenches_lists.re-wrenches.org/ > > There are two list archives for searching. When one doesn't work, try the > other: > https://www.mail-archive.com/[email protected]/ > https://lists.re-wrenches.org/pipermail/re-wrenches_lists.re-wrenches.org/ > > List rules & etiquette: > http://www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > http://www.members.re-wrenches.org > *K**irk Herander / **[email protected] <[email protected]>* *Owner|Principal, VT Solar, LLC* *Celebrating our 35th Anniversary 1991-2026!!* dba Vermont Solar Engineering 802.559.1225
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