Unusual transformer phasing error

You think that's a problem, try phasing from two outlets in a commercial building with 3-phase power!  Out last modular club outing it drove me nuts until suddenly the penny dropped!

@gunrunnerjohn posted:

You think that's a problem, try phasing from two outlets in a commercial building with 3-phase power!  Out last modular club outing it drove me nuts until suddenly the penny dropped!

This is giving me a headache.  How did you do it? My guess is you had to find breakers on the same phase by the old trial and error method?  @cnwdon, thanks for posting.

PS- Who remembers these diagrams?

Now, I do have a headache!

Yes indeed. In my case it was just trading two side by side 110v circuits, since they alternate sides of the 220 input, and it was fixed. 3-phase is another world entirely!

You can fix the issue in single phase home wiring by just reversing the plug or polarity the transformer output.  OTOH, no way to phase transformers on different phases of a 3-phase power source.

I got bit by the same thing years ago, but I guess those old gray cells died since I had to learn the lesson all over again!

@gunrunnerjohn posted:

You think that's a problem, try phasing from two outlets in a commercial building with 3-phase power!  Out last modular club outing it drove me nuts until suddenly the penny dropped!

Yes, it is a headache, easiest way to get correct phasing is to go up or down 3, 6, 9( multiples of 3) breaker spots on the same side of the panel box from the breaker spot you already are using to add another circuit. I used to be a head custodian in a school district and Technology Department had some very electronic sensitive equipment that all needed to be on the same phase as they were maxed out on the circuits they already had, and we had to wire additional circuits into their equipment room, we figured while we were running two more circuits for their needs at that time, run two extra circuits for future needs. I've been retired over 6 years from there but I heard they're using those circuits now. Tip, while running extra circuits for your layout, always run an extra one at the same time for your future needs and expansion. You'll be glad you did 5 or 10 years later!😁

My Siemens 200 amp service at home has the bus bar such that every other circuit moving up or down is on the same service leg.  Fortunately I remembered this when pulling the circuits when I finished my basement.  I guess every situation has to be looked at to evaluate what is going on.  Was good thinking on your part to figure it out.

@MichRR714 posted:

My Siemens 200 amp service at home has the bus bar such that every other circuit moving up or down is on the same service leg.  Fortunately I remembered this when pulling the circuits when I finished my basement.  I guess every situation has to be looked at to evaluate what is going on.  Was good thinking on your part to figure it out.

Yes, for standard 2 phase power, every other space on the same side up or down is the same phase, if you go to the other side, you have to go up or down one space first to get the correct phase, then it's the same like the first side, every other space up or down is the same phase. (The space directly across from the first space is the other phase)  IMO, easier in the long run to make sure all your circuits for your layout are on the same phase, so no problems if you happen to unplug something while working on the layout and accidentally plug it into a different outlet on a different phase.

@cnwdon posted:

Unusual transformer phasing error...  ...our electrician added two 110v circuits to support our large layout he unwittingly created a phasing problem that took a while and some noodling to solve...

This is one of the reasons(among a few) that the rebuilder of ZWs that is adding chassis grounding & 3 prong plugs to them should not be doing so... I recall that was one of the comments/issues I included or alluded to on his last post about the subject.