Radiative transfer in arc plasmas is one of the key issues in modelling circuit-breaker arcs properly. For a transient arc flow interaction model, the P-1 approximation appears to be a viable alternative, both from an efficiency and from an accuracy point of view. Evaluation of this approximation against other methods, such as the net emission coefficients model and the partial characteristics method, shows that the model handles the strong self-absorption at the arc boundary well and gives results with good accuracy. The method has been successfully implemented in a Euler arc-flow solver and the complete methodology has been applied to a high-current circuit-breaker arc. The computational results are compared with published experimental data.