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Effective transient thermal resistance in the earth for weekly load (transient period $\tau$ of 7 days). In the majority of practical cases, the load variations will exhibit a more complex pattern than the one described by a daily load cycle, such as for example, loading of cables is usually much lighter during the weekend than during the weekdays.
| $\frac{\rho_{4}}{2\pi} \ln\left(\frac{D_{x,w}}{Do_{d}}\right)$ | buried |
| $\frac{\rho_{b}}{2\pi} \ln\left(\frac{D_{x,w}}{Do_{d}}\right)$ | buried in backfill |
| $\frac{\rho_{4}}{2\pi} \ln\left(\frac{D_{x,w}}{Do_{d}}\right)+\frac{\rho_{d}}{2\pi} \ln\left(\frac{Do_{d}}{Di_{d}}\right)+\frac{\rho_{d,fill}}{2\pi} \ln\left(\frac{Do_{d}}{D_{eq}}\right)$ | buried in bentonite-filled ducts |