In Fig G.43 the same enclosure and breaker appears to be rotated from the vertical position in Fig G.42 ( VCB ) to the horizontal position in Fig G.43 (HCB).

Are 'horizontal' and 'vertical' with respect to a person standing vertical ( parallel to the breaker shown in Fig G.42 ) ?

Hi Murray,

Figures G.42 and G.43 on page 123 of the 2018 Edition of IEEE 1584 are the same circuit breaker from different views. The tests were conducted based on configurations in Table 9 (Page 39) and the actual test set up in G.1 and G.3 (Page 82/83) so VCB and HCB electrodes are "inside" the enclosure and the calorimeters (person) are directly in front of the enclosure so the energy would be perpendicular to the worker.

Consideration should also be given to the likelihood of an event too. i.e. what event would actually bridge the conductors in G.43 where the wire is located?

Thanks for the question!