Can I use a twisted pair for 5V and ground?
There are a couple things to take note of to know if this will work:


Peak current draw of your load: $$I_p$$
The acceptable voltage drop your load can accept: $$V_d$$
The resistance of your cable: $$R_C$$ 


If:

$$I_p \times R_c \leq V_d$$

Then you're good to go.