Dear dipil
I think your querry is well met by Mr. S Mani, what he has explained to your querry by commuting mandays for one month only. Man days worked are different to calendar days. Mandays worked in an organisation are total work days performed(excluding the rest days) i.e. calendar days * workdays per week *manpower
Calendar days in July=31, calendar days a week =7, workdays a week=5
31 *(5/7) = 22.14 days or say 22 worked in July. Say, if man power =500
Total mandays for July = 22 *500 =11071 mandays and further if you multiply with 8hrs a day gives you Manhours.
As earlier cited, your accident free mandays from Jan to July are lost if a fatal/reportable accident happens on 31st July and accedent free period starts from 1st August onwards.
Hope, I could explain it rightly to you.
Regards
drs