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Author Topic: What could cause this GFI problem?  (Read 5312 times)

Jonathan Johnson

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Re: What could cause this GFI problem?
« Reply #10 on: November 03, 2014, 05:42:00 pm »

Would a solution be to have a dedicated drop box with no GFI's specifically for "old leaky" amps?  :o

Removing a safety device certainly would prevent it activating.  :o  But could that potentially contaminate the audio ground of other devices? Could it result in a hazardous situation? In that case, I'd probably insist on transformer isolation with ground lift.
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Jamin Lynch

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Re: What could cause this GFI problem?
« Reply #11 on: November 03, 2014, 05:55:18 pm »

For the safety of the musician perhaps cut off the line cord.... Make the musician sign a waver so that he knows using an amp that trips a GFCI is a human safety hazard.

These old amps can generally be fixed without hurting the tone. Advise him to find a capable service technician. This should be common sense, and self preservation for the musician.

Explain natural selection to him. 

JR

{edit.. "well your honor, before he died his amp was tripping my GFCI, so I plugged him into an unprotected outlet". [/edit]

Get a rope.

I hear what your saying. I was really joking about the dedicated drop box thing. Hence the  :o

As far as I know, this hasn't been an issue before with either of these guys. I'm curious why that is?
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Mike Sokol

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Re: What could cause this GFI problem?
« Reply #12 on: November 03, 2014, 09:27:24 pm »

Would a solution be to have a dedicated drop box with no GFI's specifically for "old leaky" amps?  :o

Perhaps this is the spot for a high-threshold GFCI with a 30 mA trip point. Not currently allowed by code in the USA, but certainly better than bypassing a 6 mA GFCI that's tripping.

The irony is that the thing that will make the GFCI trip on power up is the EGC, and that's what's needed to protect the musician from shock in the first place. If the amp had a broken EGC, then the GFCI wouldn't trip when plugged in. It would then only trip if the meat puppet contacted a earth ground while holding the guitar strings.
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Mike Sokol
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Stephen Swaffer

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Re: What could cause this GFI problem?
« Reply #13 on: November 03, 2014, 10:56:47 pm »

Interestingly, Code is perfectly fine with GFCIs being installed without an EGC-you can even feed through to standard 3 prong receptacles without an EGC-in fact disallowed if it goes no where.  Of course, the caveat is that if no EGC is available-and intended for retrofit installs. 

Of course, that would leave an ungrounded situation as far as shielding goes as well.  A questionable solution IMO since you are relying on the GFCI for any protection-but a possibility?
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Steve Swaffer

Scott Holtzman

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Re: What could cause this GFI problem?
« Reply #14 on: November 04, 2014, 12:45:01 am »

Cutting a line cord on the bass players amp?  I value my life too.
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Lyle Williams

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Re: What could cause this GFI problem?
« Reply #15 on: November 04, 2014, 04:32:31 am »

As an aside, if you run into a circuit that trips a GFCI/RCD when a known non-leaky device is plugged in (possibly tripping only when more current is drawn) then the cause may be an extra neutral-ground connection.
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Andre Vare

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Re: What could cause this GFI problem?
« Reply #16 on: November 04, 2014, 09:52:03 am »

As an aside, if you run into a circuit that trips a GFCI/RCD when a known non-leaky device is plugged in (possibly tripping only when more current is drawn) then the cause may be an extra neutral-ground connection.
Don't tell them.

Andre
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Mike Sokol

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Re: What could cause this GFI problem?
« Reply #17 on: November 04, 2014, 10:56:32 am »

As an aside, if you run into a circuit that trips a GFCI/RCD when a known non-leaky device is plugged in (possibly tripping only when more current is drawn) then the cause may be an extra neutral-ground connection.

Yes, and a swapped Neutral and Ground will do the same thing....  :D
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John Roberts {JR}

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Re: What could cause this GFI problem?
« Reply #18 on: November 04, 2014, 05:29:23 pm »

I suspect we could plug the guilty product into a ground lift adapter and probe with a VOM on AC current scale between the chassis and outlet ground to measure leakage. (note: this assumes the guilty product is not connected to anything else that could drain off leaked current.

JR
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Re: What could cause this GFI problem?
« Reply #18 on: November 04, 2014, 05:29:23 pm »


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