Stripped screw repair

[sparky7746]

Does anyone have anything to say about repairing stripped threaded holes in electrical equipment? If it is just a cover screw hole or something like that I don't have a problem drilling and tapping to next size. However, I usually do all the similar screws in the piece of equipment so they all match and I don't need to keep track of what screw goes where or what tool I need to remove/ install it. But, I often run into equipment that has threaded holes in electrically conductive parts of equipment such as bussbars. Whenever possible I like to change the portion of bussbar with the bad hole so I can still use the identical attachment or connection method that the OEM designed. With a lot of older equipment this is not possible as parts are not available.

Are there any comments about drilling and tapping the stripped hole in a bussbar etc to a larger size, within reason of course? Any concerns with violating the equipment UL listing?

Thanks for any comments or suggestions.

 

[LarryFine]

I have no problem with your solution. Anyone qualified enough to interact with your new screw size will understand enough to put it back in the same hole. Avoid using identical screw heads.

 

[jim dungar]

Any concerns with violating the equipment UL listing?

Technically, the UL Listing was 'violated' as soon as the screw was stripped.
UL says that when equipment is modified in the field (i.e. no longer the way it left the factory) it is up to the AHJ to pass judgement as to acceptability.

 

[Dibloafer911]

I've run into AHJ's giving me the business over similar situations with grounding, not current carrying conductors. If an inspector is thorough and he/she catches it, it won't pass. If I were an inspector, I wouldn't pass that type of rework on a buss-bar or similar current carrying/buss type equipment, too risky.

Side-bar; Sometimes the UL thing can get ridiculous to where the AHJ is missing the point. For instance, I once had to remove a small chair lug that was factory installed for the EGC on a new refrigerated case because it was:

• Factory installed in such a bad position that you couldn't get a screwdriver on it to torque it down
• Factory installed with a short self tapping screw. code violation 250.8 (A)(6)
• Self tapping screw hole that the lug was fastened to was totally stripped.

So, I installed a small, UL listed ground bar. Fastened at each end with a 10/32 machine screw to which the holes were tapped. That baby was on there! you could have used it as a lifting point for the whole refer case. He failed me for violation of code 250.8 (A)(7). Can you believe it!? Because he had previously just inspected a few rows of cases and saw that they all had these little chair lugs for the EGC(all of which were installed with self-tapping screws by-the-way, and said nothing), he said my ground bar rendered the case no longer part of a "listed assembly"- IT WAS THE MOST SOLIDLY BONDED PIECE OF EQUIPMENT IN THE SYSTEM BECAUSE OF MY MODIFICATION! Sometimes both installers and AHJ's miss the point of 90.1(A), I had actually made the equipment safer. Oh well, God bless him for sticking to the code. Love ya, man