Adding to Wilfried's reply, based on the format of your files, it looks like you are targeting TinkerPop2. If you are planning to use TinkerPop3, you'll need to get the formats updated.
I was able to load the GraphML file in the Gremlin shell like this:
gremlin> g = new TinkerGraph(); g.loadGraphML('/tmp/esd_graph.xml')
==>null
gremlin> g.V()
==>v[1]
==>v[2]
==>v[3]
==>v[4]
==>v[5]
==>v[6]
gremlin> g.E()
==>e[11][5-powers->4]
==>e[12][5-powers->6]
==>e[7][1-grounds->2]
==>e[8][1-grounds->3]
==>e[9][1-grounds->4]
==>e[10][1-grounds->6]
The GraphSON file posted previously had several errors in it. There were commas missing between objects in the vertices JSON array, and there were extra trailing commas in the edge objects. Also note the case on the loadGraphSON method. I've attached an updated file to this.
gremlin> g = new TinkerGraph(); g.loadGraphSON('/tmp/esd_graph.json')
==>null
gremlin> g.V()
==>v[1]
==>v[2]
==>v[3]
==>v[4]
==>v[5]
==>v[6]
gremlin> g.E()
==>e[11][5-knows->6]
==>e[12][5-knows->4]
==>e[7][1-knows->2]
==>e[8][1-knows->3]
==>e[9][1-knows->4]
==>e[10][1-knows->6]