Proximity of Insulated Wire
In Europe the IEC and CE standard are applicable.

There are a bunch of IEC norms, but if you want to sell your product to Europe you probably will have to go through a third party certification body like TUV whom they could provide you better guidance over the vast amount of norms.

As per your question, I would say it depends what you mean by "touching", if there is a risk of abrasion. You could sleeve the wire.

For sure you would need the insulation of that particular wire to be rated for the voltage.