I have a Challenger service panel outside with a main qfp-150-2 pole breaker and it has 4 breaker bus bars below. Two slots will hold a double pole 30 AMP breaker to backfeed the panel from a generator.

I am using an interlock kit to prevent the main and Generator breaker from both being on at the same time. The problem I am having is that there is a tab to fasten a pad lock on the right hand side of the toggle on the main breaker that is in the way of the interlock.

Can this tab be remove (cut off) or is that a code violation of the NEC. I live in South Florida.

  • It looks like some Challenger service panels were not completely safe - perhaps you could check your one in case it needs to be replaced, in which case you may not have the problem of removing the padlock tab. Challenger Electrical Panel Bus Overheating Field Failure Report Commented Mar 6, 2018 at 15:46
  • The tab to fasten the padlock is often an accessory, and thus removable. Also keep in mind that interlocks which attach to the panel cover have the disadvantage that they will not function if the cover is removed, bent or loose, and as such are not always allowed. Commented Mar 6, 2018 at 17:29
  • Thanks Andrew, The panel is about 23 years old and I have looked at it often over the last 19 years and it seems to be aging well with no hot spots.
    – LeonardP
    Commented Mar 6, 2018 at 18:21
  • Thanks Harper. This tab is part of the breaker and cannot be removed without modification. I am aware and leery that the Interlock Kit may be flagged. But I needed to hear this from someone else so I think I will look for a more solid and unfortunately a more costly solution. Thanks again.
    – LeonardP
    Commented Mar 6, 2018 at 18:27
  • Thank you ArchonOSX. I though that would be the answer but I am glad to have clarification form someone with much more experience and knowledge then me. How have you seen non-UL listed bolt to the cover interconnect kits recieved by local inspectors? Would you say it would have a decent shot at getting a pass?
    – LeonardP
    Commented Mar 6, 2018 at 18:33

1 Answer 1


Technically, the National Electrical Code requires listed equipment to be used as it was manufactured without modification.

However, your inspector can approve a field modification if they deem it is necessary.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.