Adding geometry to THREE.Object3D

I've edited this post to make it more clear.

Well, What I am trying to do here is to represent a tile composed by 8 different triangles. Each triangle should be able to change it color independently.

So, the problem I'm having is that when I change the color of a single triangle it changes the color of the lines in betwen, as you can see in the second image.

This is the code to create a tile:

var tile=[];
var n=0;
for(var i=0; i<4; i++){
    for(var j=0; j<2; j++){
        var triangle = new THREE.Object3D();
        var lineMaterial = new THREE.LineBasicMaterial({color:0xffffff, transparent:true, opacity:0.5});
        var triangleMaterial = new THREE.MeshPhongMaterial({color:COLOR_OFF ,emissive:EMISSIVE_OFF ,side:THREE.DoubleSide, shading:THREE.FlatShading});

        var geometry = new THREE.Geometry();
        geometry.vertices.push( triangleVectors[j][0], triangleVectors[j][1], triangleVectors[j][2] );
        var face = new THREE.Face3(0, 1, 2);
        geometry.faces.push(face);

        triangle.add(new THREE.LineSegments(new THREE.Geometry(), lineMaterial));
        triangle.add( new THREE.Mesh( new THREE.Geometry(), triangleMaterial));

        triangle.children[ 0 ].geometry = new THREE.WireframeGeometry(geometry);
        triangle.children[ 1 ].geometry = geometry;

        triangle.rotation.z = Math.PI*i/2;
        triangle.position.x = TILE_LENGTH*x;
        triangle.position.y = TILE_LENGTH*y;

        n++;                        
        tile.push({'triangle':triangle,'number':n,'state':"OFF"});                      
        scene.add(triangle);
     }
}

To update the state of a triangle of the Tile I'm using this code:

for(var j=0;j<tile.length; j++){

    tile[j].triangle.children[0].material.color.set(COLOR_OFF);
    tile[j].triangle.children[1].material.color.set(COLOR_OFF);
    tile[j].state="OFF";

    for(var k=0; k<pathUpdates[step].length; k++){
        if(pathUpdates[step][k].number == tile[j].number){
           tile[j].triangle.children[0].material.color.set(COLOR_ON);               
           tile[j].triangle.children[1].material.color.set(COLOR_ON);
           floor[i].tile[j].state="ON";
        }
    }
}

Is this the correct way to change to modifie a material?

I simplifyed a little bit the code to show better my issue. However, the real code is in this repository https://github.com/tul1/Tile.git . If you want to take a look at it working I deployed it in http://tul1.github.io/examples/dale.html .