Capo on 4th fret.
Then C/G2 is going to be the same shape, but starting at the 4th fret.
Sounds like the way Lights plays it most when you hammer on with the Em and hammer on 
the D-string when playing the C/G variation chord.
~~~~~~~~~~~~~
C/G, Em, C/G, Em, C/G2    (2x)

C/G
Where the fence is low
                 Em
And the water is rising
C/G
And the fire comes down
                       Em    C/G2
And the dark fills the skies in
C/G
One foot on the ledge
                    Em
And I'm feeling for safety
C/G
Somewhere between sure
            Em    C/G2
And I don't know, maybe

G
I'm off of my rope here
C/G
I'm off on my own here
G
I find my hope here
C/G
I find my own here
Em
I'm off of my rope here
C/G
Where the fence is low
G                  C/G
Where the fence is low
G                  C/G
Where the fence is low

C/G                                Em
In shadow I walk to the ends of the forest
C/G
And the shape of the hands
Em                    C/G
That break the ground for us
C/G                                    Em
The fear that contains the binds like a blessing
C/G
I've been here before
            Em   C/G2
Then again, I'm guessing


G
I'm off of my rope here
C/G
I'm off on my own here
G
I find my hope here
C/G
I find my own here
Em
I'm off of my rope here
C/G
Where the fence is low
G                 C/G
Where the fence is low
G                 C/G
Where the fence is low

G                  C/G
Low, low, low, low

G
I'm off of my rope here
C/G
I'm off on my own here
G
I find my hope here
C/G
I find my own here
Em
I'm off of my rope here
G
Where the fence is low