between all the !!!!!s and

??s, PhilB does make an important point. Fires don't happen often in most offices, but we still need to cater for that rare occurance. Metronet's headquarters in paddington (telestar house) was a typical modern office block with PAT tested equipment, no smoking, no special features but it was still gutted from fire.
Mushy some times people smoke despite the ban, sometimes tested appliances burn, contractors will use heat, arson does occur, neighbours cause fires, unexpected things do happen. Fixed electrics can short, people can bring in heaters, radios. Veniding machines can be missed by testers, people may cook food, lightning can strike, fireworks can land on roofs. I could go on all day the point us that we can never predict what may happen, if we could then nobody would die in fires and buildings would not be lost.