grounding the box?

[cbriere]

i am building a box with AC line power supply inside the effect.
Should i connect the earth ground to the box?
I also have the guitar ground connected to the box
Is there a problem to do this?

cbriere

[GibsonGM]

Wow, what effect? Are you using a transformer inside the box? Hope so!  Generally speaking, yes, you would include the ground wire and use a 3-prong cord.  And if you do it incorrectly, you could be killed.   

DISCLAIMER:
I take ZERO responsibility for safety advice if you insist on using line power for your project!!!!   I suggest you find an amp forum and ask there - they would be much more knowledgable about AC line safety.  FWIW, I believe guitar grounds connect to the chassis in an amp, which is connected to the ground wire at the power supply.  There are ways that electricians/engineers design for safety, though.   Your thinking is right, but talking to one with more experience is definitely a good idea!!!