Cable diagnostics based on very low frequency tan delta and partial discharge measurements requires defining clear application procedures covering new installations, maintenance testing after repairs as well as regular inspection. Residual lifetime estimation, which is based on the latest software, then allows investment planning by asset managers. This presentation explains how quality of newly laid cables, including newly installed accessories such as joints and terminations, can be verified using a ramp up diagnostic sequence followed by a monitored withstand test covering measurement of TD loss factor and PD.