Once an initial risk assessment has been carried out, the work procedures may need to be reviewed to bring exposure to any arc energy hazard down to more acceptable levels.
At this point it helps to have in mind a standard to work towards for reducing arc energy exposures.
For example, on a board that has only fixed isolators or fused equipment you might set a standard of reducing the arc energy down to under 8 cal/cm² . It can be argued that this is reasonable as flashovers on this type of equipment are very unlikely. It might also be extremely hard to reduce arc energies as arc protection systems cannot be fitted to this kind of equipment.
However, on a board with rackable breakers, where a flashover is more likely, you may adopt a standard of reducing the arc energy to as low a value as current technology will allow. This kind of equipment can have arc protection relays fitted at minimal costs.