RBgrid

First Measurements

This walks through taking your first reading on a running hub: connect a module, bind a channel to a point, confirm the numbers are right, and fix the usual first-time problems. Everything here is done in the web app (or the API) — no code. If you have not flashed and set up the hub yet, do Build from Source (or flash a release image) and the first-boot Wi-Fi steps first.

1. Connect a module

  1. Wire an rbAmp module to the hub's I²C bus and power the hub.
  2. Clip a current transformer (CT) on a conductor — one conductor only (live or neutral, not both), with the CT's arrow pointing toward the load.
  3. For a module whose voltage input is used, connect its voltage input as described with the module.

For the physical install, wiring and the CT lineup, follow the rbAmp module docs. Give the module a few seconds after power-up — right after boot the hub probes modules and the channel list may be briefly empty.

2. Bind a channel to a point

  1. Open Points → rbAmp modules. The module appears as a card (e.g. module 0 · 0x50 · 1U + 7I · 0 of 7 in use); each current channel is listed as free until you bind it.
  2. Bind a free channel to a new point: give it a name (e.g. Water heater), a role, and a statistics depth. The channel stops saying free and shows the point name.
  3. Set the CT model for the channel to the clamp you actually fitted (for a module that takes a clamp-on CT of your choice). This applies the module's correction for that model. On a factory-paired channel the model is fixed and already correct.

The voltage input appears on its own as a Voltage bus point and cannot be deleted; so can the main input.

3. Verify the reading

Open the point and check against something you know:

  • Power is positive on a consuming load. If a load that only consumes shows negative power (a BASIC channel flags it as reversed), the CT is on backwards — turn the clamp around (or flip it in software where the module allows).
  • The value is plausible. Switch a known load on and off (a kettle, a heater) and watch the point follow it. The reading is the current on that one conductor — RBgrid never multiplies it by the number of phases.
  • No limit flags. If the channel shows clipping or sensor limit, the current is at or over the CT's range: readings are under-counted above a CT's rating and the module cannot tell, so fit a CT with a higher rating (or move it to a smaller branch). These flags also appear in Needs attention.
  • Correction applied. If the channel shows "readings not corrected", the module did not apply its CT correction — check that the CT model you set matches the clamp, and that the module recognises it.

4. Troubleshoot

No data on the point

  • The module needs a few seconds after boot; reload if the channel list was empty.
  • Confirm the channel is bound (not free) and the CT is clipped around a conductor.
  • Check the module's I²C wiring and that it appears on the expected address.

Reading is zero or tiny

  • Very small currents on a BASIC channel read as zero current, power and power factor (energy totals are not affected). Put a real load on the circuit to confirm.
  • Make sure the CT is around one conductor — a CT around both live and neutral sees (almost) no net current.

Reading is negative on a consuming load

  • The CT is reversed — turn it around (arrow toward the load), or flip the direction in software where supported.

Reading looks too high / too low by a round factor

  • Check the CT model set on the channel matches the clamp fitted; a mismatch applies the wrong correction.
  • Do not divide a three-phase total by three in your own tooling — each point already reports one conductor only.

Once the point reads correctly, add the rest of your channels the same way and set your tariff plan (Tariff Configuration) to turn measurements into costs.