bolt - in

[mnbiker]

Just wondering what others have done. Siemens panel with Siemens type BL breakers. I have some of the fingers on the buss that have stripped out. On A and C phase looks like the fingers will be easy to replace. On B phase it appears to be more of a bear. I have seen on a couple spots someone has used ground screw (10-32). I am planning a shut down to take care this and do it right, but that wont happean untill Thanksgiving weekend. Is there any tricks i can do, drill and tap to get by untill then. Thanks

 

[gar]

130905-1228 EDT

Consider a Helicoil insert. A larger hole is drilled, and tapped with a special tap supplied in the kit. The insert is stainless steel. The repair is very much stronger than the original thread. Only use Helicoil brand components.

At one time we had to test a machine that simultaneously ran many cover plate screws into an aluminum automatic transmission housing. The basic threaded hole in the aluminum would last possibly 20 to 50 cycles. To get many thousands of test cycles that was expensive in scraped housings. Instead Helicoils were inserted in the aluminum housing and one housing lasted more than 10,000 cycles.

.

 

[curt swartz]

130905-1228 EDT

Consider a Helicoil insert. A larger hole is drilled, and tapped with a special tap supplied in the kit. The insert is stainless steel. The repair is very much stronger than the original thread. Only use Helicoil brand components.

At one time we had to test a machine that simultaneously ran many cover plate screws into an aluminum automatic transmission housing. The basic threaded hole in the aluminum would last possibly 20 to 50 cycles. To get many thousands of test cycles that was expensive in scraped housings. Instead Helicoils were inserted in the aluminum housing and one housing lasted more than 10,000 cycles.

.

I think those require thick material. The buss parts the OP is dealing with are 1/8" thick at most.

The original screws are 10/32 so I would guess you are seeing ground screws where the original screws were lost. I have tapped the buss out to the next size (#12) and that seems to work well. Just make sure you use shorts screws!

 

[Volta]

I think those require thick material. The buss parts the OP is dealing with are 1/8" thick at most.

The original screws are 10/32 so I would guess you are seeing ground screws where the original screws were lost. I have tapped the buss out to the next size (#12) and that seems to work well. Just make sure you use shorts screws!

And stick with fine threads if possible.

 

[kwired]

What material is the bus?

Original bolts probably have a spring washer on them also.

Your repair may not be quite equivalent to the original, but sometimes you do what you have to do in a pinch also.

 

[curt swartz]

What material is the bus?

Original bolts probably have a spring washer on them also.

Your repair may not be quite equivalent to the original, but sometimes you do what you have to do in a pinch also.

I was under the impression that he was just refering to the standard 10/32 machine screw that holds the breaker in. I don't think there is a bolt/nut/washer.

 

[GoldDigger]

I was under the impression that he was just refering to the standard 10/32 machine screw that holds the breaker in. I don't think there is a bolt/nut/washer.

Even with the machine screw threaded directly into the bus bar, you could still put a Belleville washer between the screw head and the breaker tab to maintain pressure through thermal expansion and contraction. Although the maximum tension in the screw (and therefor the maximum torque) would still be limited by the pull-out strength of the threads in the copper or aluminum bus.

 

[iwire]

130905-1228 EDT

Consider a Helicoil insert. A larger hole is drilled, and tapped with a special tap supplied in the kit. The insert is stainless steel. The repair is very much stronger than the original thread. Only use Helicoil brand components.

I would say that is potential NEC 110.3(B) issue unless you can get the panelboard manufacturer to approve it.

 

[iwire]

Just wondering what others have done. Siemens panel with Siemens type BL breakers. I have some of the fingers on the buss that have stripped out. On A and C phase looks like the fingers will be easy to replace. On B phase it appears to be more of a bear. I have seen on a couple spots someone has used ground screw (10-32). I am planning a shut down to take care this and do it right, but that wont happean untill Thanksgiving weekend. Is there any tricks i can do, drill and tap to get by untill then. Thanks

It is my opinion the only listing compliant fix is one the manufacturer would recommend.

So if it was me I would either purchase repair parts from the manufacturer or an entire new panelboard.

Any home brew fix, no matter how effective will be a potential code issue.

 

[kwired]

I was under the impression that he was just refering to the standard 10/32 machine screw that holds the breaker in. I don't think there is a bolt/nut/washer.

Call it what you want, we still commonly call these "bolt on breakers"

Most I have seen have some kind of washer on the original "bolt" that is designed to somehow help maintain pressure during thermal expansion/contraction.

 

[iwire]

I am really at a loss to understand how washers of any type have to do with a stripped bus finger.

 

[kwired]

I am really at a loss to understand how washers of any type have to do with a stripped bus finger.

They have nothing to do with the stripped bus finger, but they are there to help maintain pressure of the connection. If you drill out the bus and use a larger "bolt" you possibly do not use the same type of washer that was on the original "bolt", possibly leading to another failure of this connection.

 

[mnbiker]

Thanks, i do plan on fixing these the right way, but Thanksgiving weekend would be the earlist scheduled shut down. Right now i do not need those breakers spaces, but the way things change around here you never know when. The 10-32 hold down screws do have a small washer on them, but it is hard to tell if it is a bellvue type. thanks again......

 

[Fulthrotl]

Thanks, i do plan on fixing these the right way, but Thanksgiving weekend would be the earlist scheduled shut down. Right now i do not need those breakers spaces, but the way things change around here you never know when. The 10-32 hold down screws do have a small washer on them, but it is hard to tell if it is a bellvue type. thanks again......

as iwire said, nothing short of replacing the parts
with manufacturers replacement parts will keep
the UL listing intact. or replacing the panel entirely.

however....

http://www.avdelusallc.com/products/nutsert.shtml

dunno what your clearance behind the buss is.... but
these might get you to thanksgiving.....

 

[Buck Parrish]

Just wondering what others have done. Siemens panel with Siemens type BL breakers. I have some of the fingers on the buss that have stripped out. On A and C phase looks like the fingers will be easy to replace. On B phase it appears to be more of a bear. I have seen on a couple spots someone has used ground screw (10-32). I am planning a shut down to take care this and do it right, but that wont happean untill Thanksgiving weekend. Is there any tricks i can do, drill and tap to get by untill then. Thanks

By do it right , do you mean ordering new guts for the panel. If it's not to old that is likely the best option. Considering of course the load.
Just for conversations sake. What type of load will be in these positions? HVAC, Lights, Motors making medical equipment, are they continuous loads. (20. 30 100 amps)
And your job is to save the company money.

Even if the facility is running 24 hours a day. I would think you could order the parts and get every thing ready.
With a little help and the same brand guts to the panel as the breakers. If the new guts fit, it's possible to change it out in an hour or so . Unless it's a huge swiich gear.
The wires would not have to be loosened on the breakers. Just unbolt them. Replace the guts with a ul approoved bus bar (guts just bolt in). Then bolt the breakers back and your good to go.
It might even be safer because you would not be working on a live bus bar. And I know how close those phases are. I just worked on one today.
It feels kind of weird to unscrew live breakers with a makita impact drill. Although the drill is mostly plastic. Their are some recessed screws in the handle. Put some Scotch 33 over them.
I don't know how old you are. But have you have seen the "Creature of the black lagoon" Well he/it was a victim of an arc flash.
You would have to have watched the first episode to know that. Of course I wached it on a rerun because I'm not old
Another option would be to install a small cheap sub panel beside it until Thanksgiving.

 

[templdl]

I would say that is potential NEC 110.3(B) issue unless you can get the panelboard manufacturer to approve it.

Ditto.
Also, since the OP wasn't referring to the bus itself are the "fingers on the bus" replaceable? We often called them bus adapters. Siemens may have a renewal parts list for the panel.