Is this tap legal?

[augie47]

Tapping two of the three phases should not be a problem.
Obviously, drilling (tapping) the buss is questionable.
I would be more concerned about the tap meeting one of the 240.21 tap rules (Length & wire size)

 

[Knightryder12]

Well copper chips are laying all over

Still I would not lose a minute of sleep over it

Good eye.

 

[Seven-Delta-FortyOne]

Is there any reason why the listing of the equipment might be invalidated by drilling new holes in the busbars? I have seen clamp-on type lugs advertised on line that do not require drilling holes in a bus.

Evidently because you have now decreased the overall volume of metal, so its capacity could be compromised.

Between being, uh, counseled here on this forum, talking to other EC’s in my area, and running slightly afoul of PG&E, I’m now much more careful about what I do. When in doubt, I throw new, expensive, factory parts at everything, instead of making minuscule modifications that will get someone’s panties twisted. I don’t care, it’s what they want, so……

 

[Jraef]

The distance between the lug on the middle busbar and the left busbar is clearly less than the distance between the busbars. I would think that may be a problem and that the lug should be rotated not to overhang the middle busbar.

Cheers, Wayne

Meh... rotate the lugs to point up, problem solved...

Although, it's probably not actually a problem here. There is a great white paper on this issue written by a PE at Powell Industries, a switchgear manufacturer. It's basically saying that the "standards" for bus spacing are more like suggestions, that the REAL issue is whether it passes a dielectric test. So in this case although the spacing may APPEAR to reduce the "required" air clearance of 1" (assuming 600V max gear), if it doesn't flash over, it's probably good.

 

[Jraef]

Evidently because you have now decreased the overall volume of metal, so its capacity could be compromised.

It's not "volume". it is cross sectional area; basically you cut a slice through any point in the bus and look at the AREA, not volume, of the surface of that slice. Right above and below this are the much larger holes drilled for the connection and mounting bolts. so the cross sectional area of the bus where these two little holes were drilled is FAR more than it would be where the larger holes are.

This is a non-issue. When I built gear, we drilled and tapped bus all the time.

 

[Seven-Delta-FortyOne]

Perhaps.

Yet switchgear has failed final because of field-drilled holes, and I know that at least some manufacturers prohibit it.

I personally think it’s goofier than a wooden watch, and no different than removing the bars between an MCB and the bus in a residential panel to feed an ATS, and yet both actions, from time to time and in different locales, will be a violation. But I don’t make the rules.

 

[jim dungar]

All field modifications, including punching conduit entries, effectively violate the UL listings. Only the AHJ can approve modifications made to equipment in the field. UL listings apply to the way it was manufactured at the 'factory'.

As long as industry standard practices are followed most AHJs would probably accept the work in the OP.

 

[acin]

those 2 bolt at the bottom of bus look like lugs

 

[electrofelon]

From UL:

Panelboards and deadfront switchboards are not Listed to have their busbars tapped unless there are existing holes in the busbars marked with the word “Tap” adjacent to the holes. Other holes in the busbar that are not marked with the word “Tap” are intended for the connection of overcurrent devices, other devices as identified by the product markings and in the installation instructions, or other uses identified by the manufacturer.

 

[ptonsparky]

I've seen so much worse and most likely participated in one or two.
I vaguely remember adding a breaker to some equipment and the Plant manager watching us finish as 350 of his employees were also waiting.

 

[ggunn]

Meh... rotate the lugs to point up, problem solved...

Although, it's probably not actually a problem here. There is a great white paper on this issue written by a PE at Powell Industries, a switchgear manufacturer. It's basically saying that the "standards" for bus spacing are more like suggestions, that the REAL issue is whether it passes a dielectric test. So in this case although the spacing may APPEAR to reduce the "required" air clearance of 1" (assuming 600V max gear), if it doesn't flash over, it's probably good.

In a related story...

I know of a case where an electrician field modified the input lugs of a 480V three phase panel to accept three parallel sets of conductors by switching out the single lugs for triples. I don't know how much room that left between one of the C phase lugs and the inside of the grounded enclosure because I only saw the panel after the fire.

 

[Seven-Delta-FortyOne]

All field modifications, including punching conduit entries, effectively violate the UL listings. Only the AHJ can approve modifications made to equipment in the field. UL listings apply to the way it was manufactured at the 'factory'.

As long as industry standard practices are followed most AHJs would probably accept the work in the OP.

Agreed Using Charlie’s Rule, 100.3(B) does not say “no field modifications allowed”, It says listed equipment must be installed in accordance with its instructiona.

And In my area, inspectors allow me and many others to pull the conductors off a meter and reroute them to an ATS, and they allow the connecting bars between the MCB and buss to be removed for the same reason.

Some get a coronary over it, some shrug.

 

[electrofelon]

Agreed Using Charlie’s Rule, 100.3(B) does not say “no field modifications allowed”, It says listed equipment must be installed in accordance with its instructiona.

And In my area, inspectors allow me and many others to pull the conductors off a meter and reroute them to an ATS, and they allow the connecting bars between the MCB and buss to be removed for the same reason.

Some get a coronary over it, some shrug.

Actually I don't think that is it for most modifications, Unless you are doing something that the instructions specifically say not to do - which is rare. The correct code for a "listing violation " is 110.2 - equipment must be approved by the authority having jurisdiction.