Tesla EV charger load management CTs don't fit Square D SC3042M200PF meter panel bus bars

[jcbottorff]

I'm installing a Tesla Wall Connector EV charger using the Tesla dynamic load management controller (Neurio device).  The EV charger talks to the load controller over a RS-485 twisted pair using the modbus protocol. This allows setting the EV charger to deliver up to a full 48A, but reduce it if needed to assure the panel input current never exceeds 160A continuously (200A main breaker, panel has 225A bus). The existing maximum load calculation does not have an extra 48A required for permit approval. The split CT clamps (photo below) they supply don't quite close when put on the bus bars, there is a 1/8" gap. The CTs say they work up to a wire diameter of 0.75", but apparently the rectangular bus bars exceed this. I'm assuming split CT's don't work correctly unless the split gap is fully closed. The CTs for the Enphase solar system fit just fine, which must have about a 1" square hole. The original plan was to put the Tesla CTs above the already installed Enphase CTs, which I read works fine as long as I leave a 1" gap (as per info from a CT manufacturer).

This panel model is quite popular for people doing solar installs. Using a load controller like this seems like a better strategy than degrading the charging rate or what in many cases would be a very expensive service upgrade.

I haven't seen any evidence Tesla has alternative CTs with a bigger hole so am wondering if I could put the CTs before the meter around the incoming utility cables, which are round and am pretty sure would fit. This section of the meter panel has a utility company seal (left of meter in below photo), so assume I would have to get the power company to at least come inspect the CTs and put a new seal on the meter upstream compartment, if they even allow CTs to be placed before the meter. It's unclear if there are any holes from this section of the panel into an an adjoining customer accessible section, so might have to drill a small hole and put a rubber grommet for the CT wires to come through. This is PG&E in northern California.  

[Ramasamy_N · Accepted solution]

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