UL Changes for stacked big breakers?

[pago cruiser]

Been awhile since I've been on the forum.
Have a project where we need to replace an existing 4000A Emergency Power Switchboard with an 8000A.
Want to keep the layout the same for spatial and cable tray locations. It does get deeper - no problems.
Provided the requirements to (2) national Panel Board vendors.
Vendor A (who provided the original EP Switchboard) has advised that UL has changed - and no longer allows stacked breakers in a Panel. We currently have (2) Sections, each with a 4000A and a 3000A breaker, stacked. As such, we now need to add an additional (2) sections in order to provide (1) breaker per section.

Vendor B has advised that Vendor A is in error. They have provided a Quote with the 8000A buss, but with stacked breakers.

I know this is not quite germane to NEC , but can anybody shed any light on who is correct on this topic? Yes, there are a myriad of other design issues, and our Engineers are working through those. But the fab of the Switchgear appears to be is UL driven, and it seems difficult to find reference to figure out which vendor is correct.

TIA

 

[ron]

There is no UL limitation that I'm aware of (guessing these are 891 switchboards) as long as the equipment is built and tested per UL with their design, it just depends on how the configuration is presented for testing.
Vendor A may not have proposed stack breakers and thus cannot provided it via their listed solution.

 

[jim dungar]

Vendor A maybe thinking of the changes to multiple main breakers which are now restricted to one per section.

Is your equipment being built as a switchboard or as switchgear, they have different UL standards.

 

[hillbilly1]

Vendor A maybe thinking of the changes to multiple main breakers which are now restricted to one per section.

Is your equipment being built as a switchboard or as switchgear, they have different UL standards.

That’s what I’m thinking too.