Legal Question in Landlord & Tenant Law in California

Yes, you can. Unless it is in your contract otherwise. Your landlord should should have fixed immediately because bad electrical can cause fires, endanger lives and also ruin electronic components (causing you money).

When I was in law school, I had no money so stayed in a rundown apartment. The bad electrical ruined my $4000 Mac Pro (which I won in a contest) and sued the landlord.

I disagree that it is so cut and dried. Mr. Wheeler is assuming that all electrical problems qualify as habitability issues. Most are but many are not. For example if a circuit breaker fails in the off position, all that happens is wiring on that circuit are switched off. Unless that circuit provides power to something that is legally required for the premises to be habitable, it is not a habitability issue. Repair and deduct is a tricky issue. I recommend against trying it without some direct personal advice based on the specifics of your situation. An internet Q&A cannot give you the situation-specific advice you need to be sure you aren't setting yourself up for eviction if you repair and deduct.

It is possible that I could give you a more complete answer and/or refer you to local resources if I knew where you are located. However, LawGuru for some unknown reason decided to stop asking questioners for their zip code. That makes it impossible for us attorneys answering questions to provide a location specific answer. In many cases what county or even city you are in is crucial to the help we can provide, especially if you are asking a Family Law, Real Estate, or Landlord/Tenant question. If you appreciate my providing you this free answer, please take a moment to contact LawGuru Support and complain about this. Thanks.