Should I alert a conventional 'Pass'
From the English Bridge Union Blue Book (Rules and Ethics):


  Unless it is announceable (
  see 4
  D
  , 4
  E, 4
  F
  and 4
  G
  ), a pass
  or bid must be alerted if
  it
  :
  (a)
  is not natural; or
  (b)
  is natural but has a potentially unexpected meaning


('Natural' has a long paragraph of definition; a natural pass is
"A pass
which does not unexpectedly convey values or specify suit holdings.")

So yes, if your bid (including pass or double) is conventional it must be alerted.