Hello Paul. Sorry about the delay in acknowledging your response to my query in the EMGS forum. Presently, I use Romford/Markits RP25 driving wheels one side insulated, and the other live. Looking at you your posts on the Scalefour site, and thank you for that, I think the easiest way for me to proceed is to scrap or offer for sale the un-insulated wheels and replace them with insulated ones and fit two sets of pick ups. My interest lies in the ex-GE lines so I am dealing with small engines and I think that I will have to mount the decoders in the tenders of my J15’s, E4 or in the case of my F5’s J69’s in the bunkers in styrene cases. I have a number of engines running with Triang X04 motors which are bolted to the chassis. Insulating both sides will go so far to deal with shorts, but the problem will still remain of the bolt passing them the motor and inot the chassis. The answer I think will be to bore the mounting hole out and use a sleeve to isolate the motor from the chassis with insulating material under it.
Once again thank you for taking the time to respond.