This question is about whether "circuits" can be grandfathered if the breaker or panel is changed but the circuit is otherwise not disturbed.

Code is NEC 2017. My existing main panel has plenty of ampacity but few spaces, and thus, is totally full. I have several potential paths for an upgrade.

One involves fitting a subpanel and moving 4 circuits (2 double-stuff breakers) there, and adding circuits there.

The other involves outright replacing the main with a very fine 60 space main panel. No more space problems!

But what happens with AFCI and GFCI requirements? If this were a new house, nearly all my circuits would require it, but I am grandfathered. Will the "new main" scenario void the grandfathering and require that nearly all circuits be upgraded to that protection? Or can I just move over my old breakers and call it good?

  • What state do you live in? I ask because my state has some allowances based on the type of wiring (ie, they would rather have breakers than fuses and upgrading to a panel or extending existing circuits only GFCI around water is required).
    – Ed Beal
    Commented Jun 21, 2018 at 16:33
  • 1
    NEC straight up, no local mods. Commented Jun 21, 2018 at 18:20

1 Answer 1


With the NEC straight up I think 210.12.D. Would require AFCI's where required (when the branch is modified, replaced or extended) the only exception is if the conductors are extended less than 6 feet with no new devices. Note I just checked with a inspector I worked with in my last county, he said 6' on either end with no new devices in our state would not require all the new code, I always read this as an extension to the end of line for a remodel with the total devices the same so even in my state and county there are some options.

  • OK, so your'e saying merely replacing the panel, or merely rerouting a couple feet to an adjacent subpanel, the "circuit would be grandfathered" and there'd be no need for AFCI/GFCI rigmarole. If there's any Code to cite, that would compel an inspector to let you by on that, I'd dearly love to hear it. I've heard of cases of people replacing a Zinsco and getting told "new panel / all new AFCIs" and I am hoping that is not true. Commented Apr 5, 2020 at 23:42
  • a straight up interpretation of the code would require AFCI but in Oregon there is an exception that allows updates of panels and devices without all the currently required protection. The inspector said we allow this to get rid of fuses and unsafe panels and he specifically said FPE and Zinsco if there was any buss issues.
    – Ed Beal
    Commented Apr 6, 2020 at 1:25

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