An electrician carrying out emergency works will do their best to make the situation better - that usually means at least making the installation safe, or safer, than when it was found. At the very least, they'll be able to diagnose and/or give you the option to isolate the affected parts. Depending on the property location, day of the week, and time of day, your emergency electrician may have limited resources i.e when suppliers are shut, and will make do with the kit and equipment he has available.