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Electrician's advice wanted: safely lifting ground

Hi all,

I've got a ground loop in my system between the preamp and multiple amps. The cheater plug experiment on the amp power cords not only solves the hum but also lowers the noise floor a bit more. So I would like to do this correctly in a safer, more permanent way.

Bringing all of the power cords in the system to one socket helped also but isn't as quiet as with the grounds lifted.

Can I change the circuit breaker to a GFIC and then tie ground to neutral at the wall socket so that there are no adapters involved? If this isn't the way to go please advise on what is. Even if I don't do this myself I'd like to know so that I can talk with an electrician.

Thanks
dan_ed

Showing 3 responses by tbg

tbg
5,263 posts
 
Jea48, our forefathers did not have this fun as their ac was ungrounded. With their stuff in wood boxes, I guess they were safe.
tbg
5,263 posts
 
Dan ed, your solutions is good only for components in which the input and output jacks are isolated from the chassis. I have seen few where there is such isolation.

Lifting the chassis ground is dangerous if there is a hot wire in contact with the chassis and you are grounded and can complete the circuit, such as being barefooted or touching the defective chassis and another grounded one.

My line stage only operates at it max if all other components have no ac ground but it does. Would Underwriters Labs take exception to this and deny certification to a manufacturer doing this? Yes. Would you city electric department? No. Do I feel unsafe? No.
tbg
5,263 posts
 
Are the jacks on both amps insulated from the chassis? You mention that Amp A has a ring suggesting that the inputs are in fact isolated. Have you tried only having Amp B on to see if you have hum? Or only Amp A on? I suspect that Amp A is causing your problem as it has two paths to ground. I have never known two components causing the ground loop, but rather two paths to ground causing the problem.
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