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Apachestar 9th June 2012 11:50 PM

Trip GFI
I have put a Sure 100W amp with a Sure PS 120AC to 26VDC. I branched the input 120VAC I connected to a 3 prong outlet box, then inserted a Apple Airport express (I use it wirelessly all the time). THis is all installed inside a mailbox (yes, it works great as the speaker sits on top of the mailbox and the height off the floor is great. The black mailboxes with the door ground off provide the housing for the stuff i mention above). The mailbox is grounded to the PS ground.

In side my house it works great. However if I install it on two different GFI, they trip. How can I troubkeshoot this and determine what I need to do to fix the problem?

Thanks, this is a great forum. BTW, I really love the setup I made. My PSB speakers do great with this setup. I just wish I could carry them out to my deck and plug it in and have it work.

Speedskater 10th June 2012 12:20 AM

It probably means that current is leaking from the AC Hot or Neutral wires to the mailbox frame. It could be resistive or inductive, but it's probably capacitive leakage.

Or a built-in power conditioner circuit could be the problem.

Apachestar 10th June 2012 03:09 PM

I'm using the Sure PS, so I'd assume it's protected to prevent this leakage. How can I check this best? It trips instantly at the GFI ( not the breaker).


Pano 10th June 2012 03:59 PM

A GFI is a differential breaker. If there is an imbalance in the current drawn on the two wires, it trips. That imbalance is just a few mA (about 5mA) for typical U.S. style GFIs. Let that be your clue to find the problem.

BTW, ground is not needed for a GFI to work.

Apachestar 10th June 2012 04:42 PM

more info on my electrical problem
I am getting a 1/10 ohm reading (about the best resolution this meter has) from the housing to the input lead I'd plug into the wall. This seems too high. The delta from the PS case to the PS ground seems to be zero. So if I isolate all the electronics from the mailbox, I assume that will do it? I mounted these with machine screws, thus giving a path, and a good ground for the mailbox. But it seems to not be necessary. Also, the wall plug I am using is three prong, but not polarized (no wide netural prong, just small size). It seems to me this cannot matter.

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