The bidomain model is the current standard for cardiac electrophysiology models. It has had great success in emulating clinically relevant wave pathologies. One area that lacks analysis, however, is its ability to predict excitability thresholds of resting tissue. This study aims to examine the effects of domain size and electrode placement on electrical excitability in the bidomain model. Resting thresholds of various domain sizes are found, with the largest size corresponding to a full rabbit myocardium. The resting thresholds are found for three different electrode placements. It is shown that, although domain size has some effect, electrode placement has more influence on electrical excitability, and it more strongly determines whether thresholds converge across different domain sizes. This finding characterizes two important factors of excitability that are often taken for granted, therefore holding implications for future modelling studies concerned with the examination of stimulus values.