UL Versus Panel Mods

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JSiemens

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I have had a number of instances in the past where contractors (including myself) have tapped a panel bus to extend power to an external overcurrent device. This is normally done when there is no space left in the panel or if it will not accomodate the desired breaker size. Tap rules are always followed.

I have always wanted to know if this is actually permitted by NEC/UL documents. Can any member please provide input or steer me to something on the WWW?

Thanks very much.
 
The only time I have done it was on a Zinsco panel, for several obvious reasons.

Now I would almost always talk them in to a service change.

You might find some thing under NEC 408 OR 409
 
Nec 408/409

Nec 408/409

Thanks for your response. I quickly looked at the NFPA 70 articles and did not readily find anything that I interpreted as relative. I have removed some of these taps in the past and see another one coming my way (a new project in the design phase). I really do not want to drill bus and install my own lugs if it is not permitted. I read some earlier threads and noted that the AHJ must approve and that they would probably apply to the UL for their approval. It is always about money and we would save a lot of it if we do the tap. I am hoping to hear from others who have "been there".
 
JSiemens said:
Thanks for your response. I quickly looked at the NFPA 70 articles and did not readily find anything that I interpreted as relative. I have removed some of these taps in the past and see another one coming my way (a new project in the design phase). I really do not want to drill bus and install my own lugs if it is not permitted. I read some earlier threads and noted that the AHJ must approve and that they would probably apply to the UL for their approval. It is always about money and we would save a lot of it if we do the tap. I am hoping to hear from others who have "been there".
Click to expand...

I'd say the AHJ would say you did such a good job tapping the bus but I'm turning you down because that panel isnt listed for that. Looks real pretty thou.:D
 
Many inspectors require manufacturer approval as you are altering a NRTL assembly.
I have found that such approval is not easy to come by, but on a recent thread here, someone advised he had obtained instruction/permission from the factory.
 
I saw a panel where someone tapped 400 amps off the busses between the main CB and busbar assembly in a NQOD panel. The pieces that were tapped are strips (tin plated aluminum?) that are bolted to the main breaker and to the bus assembly, about 8in long, with no other support. The tap was made by using self drilling sheetmetal screws to attach an aluminum setscrew lug to the buss. Scary!
 
augie47 said:
I have found that such approval is not easy to come by, but on a recent thread here, someone advised he had obtained instruction/permission from the factory.
Click to expand...

That was me and the gear was not that old. Took some time and many phone calls and e-mails. Good luck on older gear. I'll look for the before/after pics.
 
All I found out is there are a million Chris Kennedy's out there. Appears most of them are way smarter than I am.
 
I'm disappointed.

I thought this was going to be a thread about UL being taken on by our panel moderators, not panel modifications.:mad::D
 
I've seen lugs installed on the same bolts/studs that attach the main breaker to the bus bars. Tapped off those lugs to feed an adjacent panel with its own main breaker, sized to the feeder tap capacity.
 
Still looking but I thought this was the install I was looking for. In this case we did not drill the bus, we added double lugs.

 
On a new install we cut up the steel frame on a large MDP that Gee Eee goofed on, pipe entry location and called told them what we wanted to do, rebraced, they said ok and sent a guy out after to inspect before power on. Assume they fixed the paper work as needed we kept records to cover our azz. I left the Co. ; personal problem with head guy not following through on his promise.
 
I seem to remember using a type of adapter plate once that allowed the addition of lugs to bus, but without having to drill the bus. But I cant find anything on it now.
 
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