This is the 2016 edition, 286MB in a zipped file.
I'm downloading it now and will report on how useful the final copy is at that time.
[edit] The zipped file was extracted with no problems and contains 2000+ pages of the encyclopedia with full images.
You might want this in your prepper docs. of course a full hardback version may be more useful in an EOTW, post-apocalypse, no internet world. but expect to pay a high price for that. You may be able to find someone who is getting rid of their hardback versions...
http://allpcworld.com/encyclopedia-britannica-2016-free-download/Due to the likely political bias in this new edition, you may want to find an earlier version, particularly those which have useful tools and techniques from a pre-internet era.
[edit] earlier edition downloads:
2002)
https://archive.org/details/EncyclopediaBritannicaConciseOther downloads from archive.org
https://archive.org/search.php?query=Encyclopedia%20Britannica[edit] I've also downloaded the 1911 version. 1.8GB. It contains 29 PDF files, one for each book. They are good photocopies of each page but with minimal (none) images that I found (I did not scan every single page...)