What is a CT clamp and why does its direction matter?
Short answer
A CT clamp is a sensor clipped around the incoming live cable that tells the inverter, battery, EV charger or diverter whether you are importing or exporting. If it is on the wrong cable or facing the wrong way, the system misreads import as export and batteries, diverters and export limits misbehave. Direction depends on the brand.
Last checked 24 September 2026 · 1 source
In more detail
- Fox ESS: clamp on incoming live tail, arrow towards the grid.
- Other brands specify arrow towards the inverter - follow the manual.
- Meter tails stay live with the main switch off - not a homeowner job.
The facts, dated
- 01Fox ESS CT arrow must point in the direction of the grid (away from the load)
manufacturer · UK · checked 24 September 2026 · fox-ess.tech
What we saw in the field
[QA review 2026-09-24] P-12 AGREES for that brand only; direction is manufacturer-specific (consolidated verdict). | Earlier notes: Partly agrees: the plug-in install used a DIN-rail meter with CT on the line conductor 'pointing towards the house'. Correct for some brands but Fox ESS specifies arrow towards grid; direction is manufacturer-specific, so the claim should not be generalised.
Sources
- fox-ess.tech — fox-ess.tech/ct-clamp-installation-guidance-troubleshooting/
Last checked: 24 September 2026