topic Re: Transformer Primary Side automatic wiring sizes in Revit MEP Forum

Transformer Primary Side automatic wiring sizes

Anonymous — Wed, 13 Apr 2011 15:06:05 GMT

I have a 3 Phase 3 wire transformer with a 480v delta primary voltage. Is there anyway to circuit this up to the switch gear without a neutral wire? I have created a 480v Delta 3 wire distribution system in the electrical settings and assigned it to the transformer yet still it shows a 3 hot conductors and a neutral??

Re: Transformer Primary Side automatic wiring sizes

markmcmicheal — Fri, 15 Apr 2011 02:09:04 GMT

Have you tried selecting the primary side wire and changing the neutral count in the properties pallete to "0"?

Re: Transformer Primary Side automatic wiring sizes

Anonymous — Fri, 15 Apr 2011 13:09:35 GMT

I can change the tick marks, but as far as voltage drop and wire size calcs, Revit still includes the neutral.

Re: Transformer Primary Side automatic wiring sizes

Anonymous — Mon, 11 Feb 2013 20:26:32 GMT

Did this ever get resolved? Seems to still be an issue (Revit MEP 2012). Revit doesn't give you the ability to edit the wire count (it's greyed out).

Re: Transformer Primary Side automatic wiring sizes

GeeksCollaborative — Wed, 26 Jun 2013 23:45:55 GMT

Still a problem in 2014? When are we going stop being ignored electrically? Why is this and homeruns still a problem?

Re: Transformer Primary Side automatic wiring sizes

ltadachi — Thu, 17 Apr 2014 01:51:25 GMT

I'm experiencing the same problem . This is a challenge to my attempt to use a system defined feeder schedule.

Re: Transformer Primary Side automatic wiring sizes

pteague — Mon, 18 Aug 2014 20:20:43 GMT

I seem to have found a workaround for this problem. It's not great, but if you use it from the beginning, it seems to work okay.

If you already have the transformer in the system, copy it (ctrl-c). Now, delete it.

Next, paste aligned to same place (or however, you want to get it back in the model). This will keep the name and other instance properties from being deleted.

Next, connect the primary side to the panel that serves the transformer. This should make a new circuit in the exact same place in your panel. If you named your circuit or have conduit sizes or breaker sizes inputted, you will need to re-input these. If everything went according to plan, your new circuit should be neutral-free (because when you attached it to the serving panel, it was a balanced, albeit zero, load).

Now, you should be able to connect the secondary side to the transformer, and the feeder serving the transformer should still be neutral-free, even though it is now unbalanced. You should not have to re-input the information for the secondary side circuit because you did not deleted the secondary side panel.

If you're starting with a new system, if you connect primary first, then secondary, I think this should work for a full project.

I have not tested this extensively, but I have tested it in a model that I am currently developing and ran into the same problem with neutrals on delta circuits.

Hopefully this works for you guys!

Re: Transformer Primary Side automatic wiring sizes

pteague — Tue, 19 Aug 2014 03:48:21 GMT

Update:

I've done a little more testing, and I found some things you need to make sure you do in order.

When connecting the primary side to its serving panel, you need to set the breaker size, wire type, and any other "circuit" variables before you connect the secondary side. Once you connect the secondary side (unbalanced load), any changes you make to the primary circuit (breaker size, wire type, etc.) will cause Revit to add a neutral to your circuit.

Re: Transformer Primary Side automatic wiring sizes

mdurman — Wed, 10 Sep 2014 18:49:20 GMT

I'm using 2014. I disconnected the panel fed from the secondary side of the transformer, then I was able to change the wire type without a neutral. I connected the panel back, and the wire type stayed in tact not showing the neutral.

Re: Transformer Primary Side automatic wiring sizes

Bassem.Khoury — Tue, 20 Sep 2022 19:22:50 GMT

This Neutral wire issue remains a problem in Revit 2022
Delta-wye transformers do not need a neutral wire on the primary side even though the secondary load is unbalanced.

Re: Transformer Primary Side automatic wiring sizes

Chris.Staker — Fri, 21 Apr 2023 16:19:45 GMT

How has this not been fixed by Autodesk yet? For the circuit sizing on the primary, Revit should look only at the primary distribution system.

Re: Transformer Primary Side automatic wiring sizes

RobDraw — Fri, 21 Apr 2023 17:14:12 GMT

@Chris.Staker wrote:
How has this not been fixed by Autodesk yet?

Try Product Feedback or the IDEAS forum. You won't get that answer here.

Re: Transformer Primary Side automatic wiring sizes

MuirEng — Fri, 04 Aug 2023 21:01:26 GMT

dealing with this problem, disappointed but not surprised that it's been open for a while. The ideas and feedback forums are dead end routes in my experience.

Re: Transformer Primary Side automatic wiring sizes

RobDraw — Fri, 04 Aug 2023 22:39:56 GMT

@MuirEng wrote:
The ideas and feedback forums are dead end routes in my experience.

Then you haven't been paying attention to new features being added based on suggestion posted to that forum. Just because your suggestions don't make it, doesn't mean that others aren't.

Re: Transformer Primary Side automatic wiring sizes

Chris.Staker — Wed, 23 Jul 2025 19:28:08 GMT

Still an issue in Revit 2023. Revit should look at the Distribution System and Voltage / Phase for the conductor arrangement. Similarly, Wire Types that include a neutral should only be allowed to be selected for Distribution Systems that include a neutral and vice versa.

Re: Transformer Primary Side automatic wiring sizes

sragan — Wed, 23 Jul 2025 19:53:27 GMT

Solved: How to eliminate neutral from wire size in panel schedule - Autodesk Community