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[John Roberts {JR}]

Same here.  I'd estimate that at least 90% of the circuits I end up using at outdoor events are now GFIs.
I own Powersoft K3s and M50qs, and the K3s can trip a GFI on power up.  This is especially true if I power up two amps in quick succession.  However, it's pretty rare for the K3s to trip a GFI during the show.  I had not heard of the trick of lifting the ground as a work around to this problem before.  I will keep that in mind as a last resort.

I do not endorse lifting a safety ground as a permanent solution, but for a "the show must go on" incident, lifting ground (only) with a GFCI protected drop should be safe.

JR

PS: Recall at Peavey dealer seminar in Mexico last century, I learned that customers considered amps that still had a ground pin as new, while ground pins cut off meant the amps were used. 

[Scott Holtzman]

I've been having this same problem; tripping 20-amp GFI receptacles that my sub amps are on (nothing else on those circuits).  Happens when I try to push kick drum and sub drops where I need the levels to be... and sometimes just barely running the subs trips them.  If they're plugged into regular receptacles (non-GFI), I never have a problem.  I'm using K10's and set to 15-amps driving TH118XL subs.
Tops are KF650z run by PL325 (horn), PL380 (10"), and PL380 (15").  Those never trip GFI receptacles.

Everywhere we play outdoors I have to deal with this.  And we play A LOT of outdoor shows!
I understand the GFI is in place for safety, but come on.   This is ridiculous.  I doubt anyone would be hurt by me plugging my sub amps into a non-GFI receptacle.  Is this an American thing?  Sorry for my ignorance.  I need a real solution.  Thank you!

Aren't all three of those PFC amplifiers?


From my understanding that solves the issue.  So does running 240/220 with two hot legs and bagging the stupid neutral.

[John Schalk]

I do not endorse lifting a safety ground as a permanent solution, but for a "the show must go on" incident, lifting ground (only) with a GFCI protected drop should be safe.

I had a chance to try this work around out yesterday, and it did not work for me.  The gig was a private party, but it was their 11th annual event (first time for me though), so they had a power drop right next to the deck, which was the stage.  All the circuits were GFIs and nothing I tried would allow me to energize either of my K3s using any of the circuits on the power drop.  I ended up running two extension cords into the garage and picked circuits that were on different walls and the rest of the show went smoothly.  Fun event otherwise and we slammed the door on the van just before it started to rain!

[John Roberts {JR}]

I had a chance to try this work around out yesterday, and it did not work for me.  The gig was a private party, but it was their 11th annual event (first time for me though), so they had a power drop right next to the deck, which was the stage.  All the circuits were GFIs and nothing I tried would allow me to energize either of my K3s using any of the circuits on the power drop.  I ended up running two extension cords into the garage and picked circuits that were on different walls and the rest of the show went smoothly.  Fun event otherwise and we slammed the door on the van just before it started to rain!

So using a ground lift plug the GFCI still tripped when you powered up the K3s? 

Were the K3's audio inputs connected to other grounded SKUs?

JR

 

[John Schalk]

So using a ground lift plug the GFCI still tripped when you powered up the K3s? 

Yes.  I have two amp racks, each with one K3 and one M50q, deployed for Left & Right.  I like to run a separate circuit to each amp rack, so they were initially plugged into two of the 12 available GFI circuits in the "power drop" next to the stage.  I only tried lifting the ground on one of the circuits.

Were the K3's audio inputs connected to other grounded SKUs?

SKU?

The amplifier's inputs were connected to a DL32 stage box that was plugged into a Monster power conditioner that was plugged into a separate GFI circuit in the power drop.  FOH was plugged into the same circuit as the stage left amp rack because I was only using the K3 in that rack.  I ended up running two extension cords into the garage to what were hopefully two separate, grounded but not GFI'd circuits for the amp racks.  The stage box and all of the stage power remained plugged into GFIs in the power drop.  That worked.  The system was quiet and I didn't trip any breakers although this was not a high volume event. 

[John Roberts {JR}]

Yes.  I have two amp racks, each with one K3 and one M50q, deployed for Left & Right.  I like to run a separate circuit to each amp rack, so they were initially plugged into two of the 12 available GFI circuits in the "power drop" next to the stage.  I only tried lifting the ground on one of the circuits.
SKU?

Sorry about the jargon... SKU=shop keeping unit, or shorthand for a product, like another amp.

The amplifier's inputs were connected to a DL32 stage box that was plugged into a Monster power conditioner that was plugged into a separate GFI circuit in the power drop.  FOH was plugged into the same circuit as the stage left amp rack because I was only using the K3 in that rack.  I ended up running two extension cords into the garage to what were hopefully two separate, grounded but not GFI'd circuits for the amp racks.  The stage box and all of the stage power remained plugged into GFIs in the power drop.  That worked.  The system was quiet and I didn't trip any breakers although this was not a high volume event.

If the leaking fault current found an alternate path to safety ground through wiring to a connected and grounded amp that would still trip the GFCI protection. GFCI only cares when leakage occurs from the line-neutral loop. It doesn't care where it goes.

JR

PS: I don't expect PFC to have an impact, I do suspect RF hash filters on switching PS amps dumping noise current to into ground. 

[Stephen Swaffer]

So lifting the safety ground of the amp isolates the chassis from ground.  I could see this working for a stand alone amp-but what about an amp mounted in a rack with something else that grounds that amp chassis?  The GFCI receptacle itself doesn't monitor or care if the ground is hooked to anything.  Code says anything that is likely to become energized needs to be bonded to a grounding electrode system.  If everything in the floating system is supplied with working GFCIs it could be safe-maybe.  Is that good enough?

If it's an amp design that is not happy running on a GFCI, is the correct solution (from a safety standpoint) to change code and not use GFCIs or would it make more sense for the amp engineers to sharpen their pencils and come up with a better design?

[Brian Jojade]

So lifting the safety ground of the amp isolates the chassis from ground.  I could see this working for a stand alone amp-but what about an amp mounted in a rack with something else that grounds that amp chassis? 

In my experience with the iTechs, lifting ground from the amp itself was all I needed to do. Other equipment in the same rack remained properly grounded and it worked.

Now, I'm not sure if there was any connection to the rails that would have given a ground path since the rails and amp weren't scrached up and coated with paint.  Something I can test if I get a chance.

[Randall Cook]

So, what I've learned from this is that my Powersoft K10 amps are no longer useable for anything outdoors or anything that has GFCI circuits.  This is sad.

Maybe I should ask; what amps can run off of a GFCI 20-amp circuits and properly power 4 Danley TH118XL?

I am currently running one K10 amp per pair of TH118XL on separate circuits.

It seems as if this is an amplifier issue.  So my two K10 amps might be for sale.

[Dave Garoutte]

Maybe I should ask; what amps can run off of a GFCI 20-amp circuits and properly power 4 Danley TH118XL?

Two channels on a DNA20K4

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