Probably all of the same brand would do this, but it might be a quality control question.
It might also have to do with the wheel tread width you have. Since you say OO, I suspect it's British. Some of their equipment has wide flat wheels and this goes over the insulated area that was supplied. Is it all your rolling stock that shorts or just certain ones? (The plastic wheeled ones shouldn't short).
There are more complicated ways involving extra wiring and switches.