Pronunciation of English Vowel Sounds 2 - Front Vowels, Part 2

Hyphens with Common Prefixes, Part 2

The current trend is to do away with unnecessary hyphens with common prefixes.

Examples: 
noncompliance
copayment
semiconscious
unending

However, there are exceptions.

Exception: Hyphenate all words beginning with self except for selfish and selfless.

Examples:
self-assured
self-respect
self-addressed

Exception: Use a hyphen with the prefix ex.

Example: His ex-wife sued for nonsupport.

Exception: Hyphenate prefixes when they come before proper nouns.

Examples:
un-American
non-English speaker

Posted on Tuesday, February 1st, 2011 at 10:33 am

fuente : http://data.grammarbook.com/blog/hyphens/hyphens-with-common-prefixes-part-2/