Your description is unclear as to what you are doing. Rebath is a renovation product with an acrylic face; it isn't a tile backer board. It often has a fake tile pattern in it. If the plastic panel is installed correctly with all the edges sealed you should not have a problem. However, you must replace the sealant if it starts to fail as with any shower installation. If you are installing tile you should use a cement backer board. If it is new construction I would recommend using a 1-piece or 2-piece tub/shower unit. I have no idea what a rescind period or pulling permits has to do with this design issue.

Them Europeans do have some good ideas as PEX (& masonry heaters, etc.) has been in wide use there long before here. However, their bonding at the fixtures appears to be overkill. The only grounding rqmt for single-family residences, in the U.S., is at the point of entry to the house. Any charge in the water system would be shunted to ground at that point and the circuit breaker should cut-off the electrical source. Of course, neither method protects completely if you are in the bath/shower and a non-GFCI electrical applicance falls in. As part of the Pentagon's renovation I observed the installation of the new copper piping and never saw grounds beyond primary supply points on each floor/wing. So apparently even commercial codes don't require bonding at the fixtures. Wonder why Europe requires it.

I spoke with a family member at holiday dinner who does industrial control systems and electrical/mechanical facilities design. He had the following thoughts regarding this issue: - 99% of power distribution systems he'd seen use only ever use fan-out for return-path conductors, no additional connections are used commonly, even on parallel lines on the same phase/circuit. - the 1% that DO have multiple conductors connected at multiple points are for critical control systems with redundant power requirements and have special monitoring, design constraints, etc. and none are common in residential. - Although the NEC may have something to say (which he wasn't sure), most common troubleshooting methodologies would not support connecting the multiple neutrals anywhere except the switch box since if there was a conductor failure, the load would positively indicate the failure and the single tie at the switch location would likely speed troubleshooting. - In some cases (although not in this case), the operation of GFCI would be affected by connecting diverse neutrals on the same branch, even with adjacent loads (i.e. if there's a GFCI receptacle inline on one of the load lines). This factor is in play here since it's my master bath and will be GFCI protected. Maintaining good circuit design for support-ability makes sense to me, so unless there IS a stipulation by the NEC, I think that's the way I'll go. Hopefully I didn't use the wrong terms for anything this time :) Dan

thisisnotadrill - thank you for responding! The tiles is from Avalon Tile, and labeled "Boucle" - but I saw the same - or very similar - tile in two other tile shops with two other different names - same with some other tiles - I saw ones that I suspected were exactly the same under a different name. I suspect that manufacturers sell to multiple companies, and likely the purchasing company gives particular tiles its own unique name.