I got fed up with house fires a long time ago and have been using a mod called "no house fires" by Cyclelegs. I don't care if it's cheating and that I never get any more house fires ever again (there are a gazillion other ways to mess with our sims and/or kill them). My sims can freely cook to their hearts content, relax by the fireplace, or roast marshmallows on the firepit without having to worry about catching fire every ten minutes. Plus the added bonus of never getting house fires...? No more having to waste simoleons buying fire alarms for every house.
There's a choice between two mods from
Cyclelegs:
1) no house fires (never get them again)
or
2) less fire (reduces the number of house fires but doesn't get rid of them completely)
I've been using the first mod for a few years now and have yet to ever need the mod to be updated with any of the new patches or packs we've had during that entire time.