Landlord legal requirements to code

[Alyssa McDonald]

Hi BP community!

Have others found resources in your state/city that have provided explicit guidelines for landlord responsibilities for keeping items up to code? 
I’m trying to plan for an older property that I’ll swap from my house hack to a LTR in the next few months. The house has a few (expensive) items not to code - things like the electrical box and radon mitigation system. I’m trying to figure out where to find a source of truth for legal requirements as a landlord to update these type of items and on what timeline I’m potentially obligated to do so.

I’ve talked to some who have said generically that if the items were in code when the house was built, I have no legal obligation to make the updates before tenants move in. 
Curious if others have experience with this or can point to any helpful reference materials.

Thanks everyone!

Alyssa