quick tip, if you don't have a gromet, silicone can be used for an acceptable finish, coat the whole hole & wire, stick it in a bit more & a bit more silicone.
the difference is that a grommet will garentee the wire has a rubber barrier to the sharp edge where with silicone it can still have the wire touching the edge, but if it doesn't move at all (it won't when fully cured) it' a whole lot better than just drilling a wire & sticking it in a dry sharp hole
