Terminal compartments are part of a traffic signal installation that allows circuits to be connected without using splices in pull boxes.  The picture below shows what is inside.  There are two pictures of the same terminal strip, taken from either side.  In the first picture you will see the posts numbered from 1-12.  The posts go all the way through.  In the second picture you can see single wires attached to 6 of the posts.  You can attach up to 3 wires per side, or 6 wires total. 

 


So if you have one Phase 2 head on a the pole with this terminal strip, you would have a set of three wires (red, yellow, brown) coming up the pole and attached to posts 1-3 on one side of the strip.  On the other side of the strip you would have another set of three wires going to the head.  If it’s a mast arm pole with another Phase 2 head on the mast you would have two sets of three wires, one to each head. 

If the Phase 2 circuit needs to continue on past this pole, you would have two sets of wires on the first side of the strip, one from the controller side of the conduit path and the second going away.