Abstract: While increased use of plug-in electric vehicles (PEVs) has environmental and economic benefits, the increased load is expected to strain components of the power delivery infrastructure. Within electric distribution systems, overloading of transformers and underground cables and associated thermal degradation is of particular concern. The current paper estimates the effect of different levels and types of PEV charging on transient heating of underground cables. Transportation survey data is used to estimate travel miles and arrival/departure times for a typical residential neighborhood, which is subsequently used to estimate the electric load curve with different levels of PEV penetration. The estimated load curves are used to perform transient heat transfer computations for a system of three buried cables using an overset grid finite-difference approach, the results of which are used to estimate acceleration of cable thermal degradation. Vehicle charging, even for a modest 30% PEV penetration, is found to nearly double peak temperature rise above ambient at the cable surface, increase the daily variance in cable temperatures, and significantly decrease the estimated time to failure for cables with thermally sensitive insulation.