My guitar picks up a lot of AC noise. It is the worst when I am using the bridge pickup. If I select the neck pickup or both it is much less apparent.

I am using an Epiphone Flying V with an SH-4 in the bridge and an SH-2n in the neck.

I thought it might be due to poor shielding so I tried to shield the control cavity with some aluminum foil tape but it didn't seem to have much of an effect.

How else can I reduce the amount of noise the guitar picks up?