Others could explain it to you in technical terms, but, some electronic devices with capacitors can interfere with the DCS signal. The Big Boy has a lot of features being powered.
Alternating the common connection is good idea mentioned earlier. The DCS is carried on the Hot or center rail. Some have questioned the Atlas terminal joiners for good connection. I can't say for sure. The "SCREW IT" method is definitely solid.
Many are able to operate both systems and equipment without issue. Proper wiring schemes and distribution using 14 or 12 for main bus and 16 for feeders is known stable.
I don't think that you should be isolating any common rails. That's more of a power district thing for conventional running. The PH 180 should operate the layout just fine. Get another rather than a Z4000, just my opinion.
Wire the layout for DCS and anything else should be ok.
May want to post the question to the forum on the Lionel Big Boy causing DCS issues.
