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[Tim McCulloch]

This becomes a question of risk assessment.  I'm pretty sure the amp is dumping some kind of nasty hash back up the neutral.

Why are your amps on a GFCI circuit?

[Randall Cook]

This becomes a question of risk assessment.  I'm pretty sure the amp is dumping some kind of nasty hash back up the neutral.

Why are your amps on a GFCI circuit?

All events that we play outdoors, we are provided with GFCI circuits. 

I'm "shocked" that my Powersoft K10 amps are tripping these GFCI circuits.  (pun intended)  It seems like their technology would be better than to trip these types of circuits. 

Is it these amps?  How many other people have this same issue?  Same amps?  other amps?

[John Roberts {JR}]

This becomes a question of risk assessment.  I'm pretty sure the amp is dumping some kind of nasty hash back up the neutral.

The GFCI current detection loop is between line and neutral so noise current flowing from line to neutral is valid and ignored.

I can imagine a filter pulling current noise from line or neutral and dumping that to chassis ground. This should be well known to amp designers by now, and their customer service departments regarding old designs. 

JR

Why are your amps on a GFCI circuit?

[Brian Jojade]

Is it these amps?  How many other people have this same issue?  Same amps?  other amps?

My Crown iTech 5000's are NOT GFCI friendly.  If I end up only having a GFCI outlet available, I have to lift ground on the power into the amps.  I guess removing safety ground is less of an issue when you're on a GFCI outlet, and it's what Crown tech support told me to do.

Seems odd though that they can have gear that's likely going to be used outside which means it's likely going to be on GFCI outlets, but the design isn't compatible with GFCI.

[John Roberts {JR}]

My Crown iTech 5000's are NOT GFCI friendly.  If I end up only having a GFCI outlet available, I have to lift ground on the power into the amps.  I guess removing safety ground is less of an issue when you're on a GFCI outlet, and it's what Crown tech support told me to do.

Seems odd though that they can have gear that's likely going to be used outside which means it's likely going to be on GFCI outlets, but the design isn't compatible with GFCI.

GFCI/RCD are a relatively recent development. Sounds like my speculation, switching noise filters dumping hash into chassis ground.

Instructive perhaps that it is >6 mA to trip GFCI fault.

Indeed GFCI can still protect the meat puppets even with safety ground lifted, but other connections to the amps might ultimately provide a ground path for the fault current and still trip the GFCI.

JR

[Tim McCulloch]

All events that we play outdoors, we are provided with GFCI circuits. 

I'm "shocked" that my Powersoft K10 amps are tripping these GFCI circuits.  (pun intended)  It seems like their technology would be better than to trip these types of circuits. 

Is it these amps?  How many other people have this same issue?  Same amps?  other amps?

I haven't used an exterior Edison outlet in years.  Code calls for GFCI protection of "outlets used by personnel."  We have a distro that has GFCI protection for backline power stringers and stage power drops.  Amp racks have their own, internal power distribution and the outlets are not accessible, so they don't have GFCIs.

Changes in the newest edition of the NEC madates GFCI protection of certain locking, multipole connections (Twist-Lock) and other services that have not heretofore required it.  Most jurisdictions have not yet adopted the latest Code, so we have some time.  I suspect that there will be a re-revision in the next edition of the NEC after nuisance trips cause problems.

[Keith Erickson]

In my experience, GFI outlets seem to always trip when using the following amps. 

I-Tech
I-Tech HD
Macrotech I
Powersoft
Lab Gruppen PLM20K, 12k44, 20k44

What do these amps all have in common?  Auto Sensing, Auto switching, Regulated, Universal Voltage, Power Factor Corrected power supplies.

QSC PL3XX amps do not have this type of power supply.

It seems there is something about this power supply design that the GFI circuit doesn't like.

Note: I don't use or allow GFI outlets when I'm deploying a system but once upon a time a couple I-techs got plugged into a spider box at a Relay for life event and the GFI's blew constantly.  Made them find another PD for us to use but because of that I did some testing with other amps and had the results listed above.

[Brian Jojade]

In my experience, GFI outlets seem to always trip when using the following amps. 

I-Tech
I-Tech HD
Macrotech I
Powersoft
Lab Gruppen PLM20K, 12k44, 20k44

What do these amps all have in common?  Auto Sensing, Auto switching, Regulated, Universal Voltage, Power Factor Corrected power supplies.

QSC PL3XX amps do not have this type of power supply.

It seems there is something about this power supply design that the GFI circuit doesn't like.

Note: I don't use or allow GFI outlets when I'm deploying a system but once upon a time a couple I-techs got plugged into a spider box at a Relay for life event and the GFI's blew constantly.  Made them find another PD for us to use but because of that I did some testing with other amps and had the results listed above.

I had some QSC PLD 4.5 amps that had universal power supplies as well. These didn't trip GFCIs.  Something different with the design, clearly.

[John Roberts {JR}]

I had some QSC PLD 4.5 amps that had universal power supplies as well. These didn't trip GFCIs.  Something different with the design, clearly.

I expect newer amps don't have this problem. Probably amps with early switching power supplies and severe filters to pass emissions testing.

But just speculating on my part. I never encountered this when was in the trenches.

JR

[John Schalk]

All events that we play outdoors, we are provided with GFCI circuits. 

Same here.  I'd estimate that at least 90% of the circuits I end up using at outdoor events are now GFIs.

Is it these amps?  How many other people have this same issue?  Same amps?  other amps?

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. 

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