For reference, here is a shop drawing of how feed through lugs is shown by a manufacturer:

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1 Minimum Needed I would need the ability in revit to treat three panel families as one three section panelboard, more specifically: Add a parameter or row in the panel schedule for feed through lugs (FTL) to be able to circuit one panel section to the next without taking up any part of the regular circuit directory of the panel schedule. The circuit number for this circuit could be FTL instead of a number. Keep the panel sections at 3 separate revit families to allow only one asset tag parameter to be filled out to have an asset tag number at each panel section. Have the load balancing feature in Revit be able to recognize when 3 panel families connected via feed through lugs in order to balance all sections at once, not just the section you are in. o (FTL could be used for any configuration where it s not simply to connect a 3 section panel to itself, ie. a 400A panel could have 125A FTL to a completely different panel in a different location) Add a feature to revit to be able to change the circuit numbing starting number for the second and third panel sections. o Ideally, if you add a feature for Revit to recognize what three panels are part of the same multi-section panel as recommended for the load balancing, this could be changed automatically based on how many circuits exist in the first panel sections. (ie. for a 3 section panel with 42 circuits each, section A numbers can be 1-42, section B is 43-84, and section C is ) For designers, I recommend the feed through lugs would appear on its own row just below the panel schedule header, yet above the circuit directory. It could have column headings as Circuit Description, Rating (Same as Trip Below), and A B C for load calculations. For reference, here is a shop drawing of how feed through lugs is shown by a manufacturer:

2 Sub-Feed Breaker Ability in Revit for a Designer I strongly recommend that at the same time FTL is added, sub-feed breakers are added. This is another feature Revit does not have that can really matter for design. The work-arounds we use do not always work well and this is a needed feature. For designers, a smaller lighting and appliance (manufacturer industry terminology) panelboard can often only have 1 or 2 sub feed breakers, though possibly up to 4. There are manufacturer specific rules of how many of what size actually fit in the panelboard. Often one 150A-250A breaker could fit or two 125A breakers. There could be an add sub-feed breaker button in Revit when you select the panel and when you are in the schedule. It could appear in a row below the top of the panel schedule header and above the circuit directory, just like I recommend for feed through lugs. It could be in its own row(s) right below the FTL row and have the same headings as the circuit directory below it. The CKT column (circuit numbers in revit) could simply be SF1, SF2, SF3, SF4 (SF abbreviating sub-feed). They could be either 2 pole or 3 pole, and maybe even 1 pole in a rare case so there would need to be a way to adjust that.

3 Ideally, Revit could add parameters to warn designers of what may not fit in a panel in the future by working with manufacturers. I would consider that extra and not necessary today. An example of one or two sub-feed breakers in a single phase panel: An example manufacturer shop drawing of a sub-feed breaker:

4 Additional panel construction details mainly for a contractor Though I don t think the contractor features in this case are necessary now, I will try to describe what they would care about if they wanted to model a panelboard as it is built. There are some existing renovations where these features would be useful to a designer, but they are few and far between if the above features that I need above are in place. I also want to note that the features above where the feed through lugs and sub-feed breakers are listed in their own rows above should still be the default even if the below features are added. This is because as a designer you don t want to mis-lead a contractor by showing a detailed constructability drawing where the FTL is on top when in actuality you are just trying to show that FTL are in the panel either at the top or the bottom. The contractor would still be responsible for coordinating the physical construction per the features below. For the main circuit breaker, main lugs only, feed through lugs, dual main lugs, and sub-feed circuit breakers it would be ideal if they could be placed below or above the panel circuit directory area.

5 My thought on how this could be in revit would be buttons that appear when you re in the panel schedule, something like the following: BUTTONS: Show MCB Show MLO Show FTL Show DML Add SFB Move SFB Top Top Top Top Top Across Show MCB Show MLO Show FTL Show DML Add SFB Stretch/Shrink Bottom Bottom Bottom Bottom Bottom SFB NOTES: Either top Either top Either top or bottom, or bottom, or bottom, not both not both not both Dual Main Lugs (DML) are FTL installed in conjunction with the MCB or MLO always on the load side (panel bus or circuit directory side) of the MCB Sub-Feed Breakers (SFB) could be at the top and/or bottom SFBs can take up both sides of a panelboard in some cases, or one side.

6 These features would allow a modeler to show the physical configuration of these elements, but dimensions or being shown to scale would not be needed. Similarly, distribution panel breaker spaces are based on the inches the breakers take up, which don t necessarily align with the circuit numbers. It is constantly an issue in the field to translate a panel schedule circuit numbering onto the circuit number stickers shown for these distribution paneloboards. Maybe someday Revit could allow modeling a power distribution (manufacturer industry terminology) panelboard differently than the lighting and appliance panelboards to allow for this to be accurately modeled. Though that may be a task that is very manual or specific to each manufacturer. Ideally, Revit could have an additional schedule type for these two different types of panelboards. Power distribution panels do not have sub-feed breakers. A feature that might resolve this issue is to have the power distribution panel schedule type be able to have different row heights for the odd number circuits than the even number circuits. Then it could be shown as the 800A 3P breaker in 1,3,5 actually lines up with 2,4,6,8,10, and 12 with small 20A 1P circuit breakers. Dual Main Lugs configuration diagram: