Is cadwelding a polyphaser bonding conductor to building steel a safety concern?

[Installer]

We have to bond a polyphaser bonding conductor to a building column. My team is concerned that the cadwelding process will heat the beam up and ignite combustible materials like drywall, OSB or insulation in the vicinity of the beam.
Then fire alarms will go off and part of the building is an elderly treatment facility and evacuation would be problematic.
This is a pretty hefty beam and the cadweld process is an instant of high heat. Would the steel would dissipate the heat quickly or slowly like if we were using a torch?

 

[TwoBlocked]

Is this an I-beam? If you can drill and tap at the center of the web, it will not affect the strength.

 

[infinity]

Will drilling and tapping a 1/4-20 hole really weaken a beam? If it's very thick you don't even need to go all the way through with the #7 bit. A few threads with a bottom tap will work.

 

[TwoBlocked]

Will drilling and tapping a 1/4-20 hole really weaken a beam? If it's very thick you don't even need to go all the way through with the #7 bit. A few threads with a bottom tap will work.

I wouldn't think so either, but if some know-it-all makes a stink, it has been put in the least weakening place.

 

[infinity]

I wouldn't think so either, but if some know-it-all makes a stink, it has been put in the least weakening place.

I can see that happening but I'm not buying it having any detrimental effect on the strength. I've through drilled and drilled and tapped dozens of beams and no one ever mentioned it being an issue. You can always use a stud welder to tack a threaded stud to the beam. I've done that when needing to attach conduit racks to vertical steel.

 

[tom baker]

I have installed 50+ polyphasers with hundreds of cadwelds. An inside cadweld is not advised. It is fast but a lot of smoke and if then mold leaks there is dripping metal. How is the connection to the polyphaser made? The polyphaser has a small hole and is intended to be bolted to a copper bus, the bus gets bonded via a bond wire to a grounding electrode. Why cad weld the other end when one end has be a bolted connection?

 

[Installer]

I have installed 50+ polyphasers with hundreds of cadwelds. An inside cadweld is not advised. It is fast but a lot of smoke and if then mold leaks there is dripping metal. How is the connection to the polyphaser made? The polyphaser has a small hole and is intended to be bolted to a copper bus, the bus gets bonded via a bond wire to a grounding electrode. Why cad weld the other end when one end has be a bolted connection?

That makes sense.

 

[Geber]

I have installed 50+ polyphasers with hundreds of cadwelds. An inside cadweld is not advised. It is fast but a lot of smoke and if then mold leaks there is dripping metal. How is the connection to the polyphaser made? The polyphaser has a small hole and is intended to be bolted to a copper bus, the bus gets bonded via a bond wire to a grounding electrode. Why cad weld the other end when one end has be a bolted connection?

I've seen a recommendation to Cadweld the grounding conductor* to the copper buss bar. Of course, this could be done outdoors before the buss bar is installed, but you would have to measure out the conductor first. How do you do it?

* I know NEC might apply different terms to the conductor, depending on exactly how it's being used, and if it's for communications, NEC might not even apply.

 

[garbo]

Will drilling and tapping a 1/4-20 hole really weaken a beam? If it's very thick you don't even need to go all the way through with the #7 bit. A few threads with a bottom tap will work.

Trying to remember from 50 years ago but thought I read some where that a 1/4-20 screw or bolt is only good for 225 amps so it might have to be increased to 3/8-16 bolt or larger. We had a retired navy engineer back in the 1970's that would not allow us to drill & tap any steel beams. I asked him if that was in the NEC or other book. Told me it was his rule. Drilled & tapped hundreds of holes in steel ,cast iron, aluminum etc and never had a beam, angle iron, etc or a leg with a heavy load ever crack or cause a breakage at tapped hole.

 

[infinity]

Trying to remember from 50 years ago but thought I read some where that a 1/4-20 screw or bolt is only good for 225 amps so it might have to be increased to 3/8-16 bolt or larger.

I can see a concern if the bolt were being used as a stud and there was no contact between the terminal and the steel but the bolt is merely holding the two surfaces together. The contact point between the lug and the steel is what's important.