It's not an issue of how often they false trigger, or if they ever
false trigger at all.
If you want to put a GFI on your fridge circuit - go ahead. There used
to be a guy here named Tom Horne, and he had every version of the NEC
ever released memorized.
He could tell you if there are any rules in the NEC that prohibit the
use of a GFI on EVERY circuit, specifically on the utility circuits in
your kitchen. I think Doug's constant posting of complete crap made Tom
lose hope though, I havn't seen him post here in a long time.
I can tell you that as *I recall*
(from the period I worked full time
as an apprentice electrician, regardless of the people who will insist
I am a plumber, or am not at all qualified in any way to comment on
electricity or electrical related items) in a house your age the smoke
have been wired on a dedicated circuit, and they
also all have a third conductor which causes all of them to
fire if any one of them fires.
I say this to you because *if*
your smokes are all on one circuit - and
(for whatever reason) the GFI you put in that circuit trips - the
chances are VERY GOOD that you won't notice it.
And in this situation, you have turned a life saving device into a life