Which is Safer? AFCI/GFCI Protection on Knob and Tube Wiring or New Wiring Without AFCI/GFCI?

[Molo]

I'm currently overseeing a residential renovation project where the electrician is replacing old knob and tube wiring, and it led to a question:

Which is Safer? AFCI/GFCI Protection on Knob and Tube Wiring or New Wiring Without AFCI/GFCI?

Note: I know that AFCI is required for new work. This is a theory question

Thank you in advance for any replies.

 

[Jadnashua]

IF you could get the AFCI breaker to not trip (maybe not likely with K&T), once the wiring was enclosed, maybe the K&T. But, since anything that old will likely have the insulation cracking or non-existent, and if any were to run in say a basement ceiling, or somewhere else where it could be accessed, It would be problematic. Insulation touching it where the insulation was compromised, or lots of other situations may mean an AFCI would never hold. Also, when that stuff was installed, it rarely ran more that a few lamps. Today's home tends to be using LOTS more power, so the wiring could easily be overloaded.

Given that new installs must meet current codes, it's sort of a moot question.

There are situations where having a safety ground adds safety (but most stuff today where that was an issue is double-insulated), but the reason GFCI and later AFCI were introduced was first to make electricity distribution in a home safer. AFCI makes the home safer by helping to prevent fires, whereas the GFCI protects animals - both human and any pets. Prior to polarized plugs just turning on a table lamp could be dangerous if the plug happened to be inserted one way versus the other.