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Author Topic: GFI's Tripping  (Read 1087 times)

Steve Garris

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GFI's Tripping
« on: October 29, 2017, 07:19:48 pm »

Only my second post on this Power forum and I don't know much about power, so bear with me.

Yesterday I did a show at a brewery taproom. My system is a small, active SRX speaker over sub per side, and 4 Yamaha DSR monitors. The board is a Mackie DL. While setting up, I ran my power strips around the stage coming from a dedicated GFI outlet. While I was turning boxes on, the GFI tripped. Next I split my stage power to another GFI box and all was good. Later as the bands were showing up and plugging in, the first GFI tripped, so I moved it to a 3rd location, then it tripped. As this point I was running out of options so I split the power to all 3 GFI outlets. This got me through the night, but one of them tripped during the break (thank goodness).

I was told by management that no one else has had this problem, and I advised them that neither had I. The venue also has a 220 GFI outlet at the stage area, and I believe the other sound providers have used that, but I'm not sure.

Any ideas or suggestions? The outlets tested good with my cheap receptacle tester (I know, I need better). I'm thinking about getting a distro box for myself, but I need to do some reading.

I've bookmarked TJ's page on stage power BTW, need some time to go over it.
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Rob Spence

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Re: GFI's Tripping
« Reply #1 on: October 29, 2017, 08:30:59 pm »

Only my second post on this Power forum and I don't know much about power, so bear with me.

Yesterday I did a show at a brewery taproom. My system is a small, active SRX speaker over sub per side, and 4 Yamaha DSR monitors. The board is a Mackie DL. While setting up, I ran my power strips around the stage coming from a dedicated GFI outlet. While I was turning boxes on, the GFI tripped. Next I split my stage power to another GFI box and all was good. Later as the bands were showing up and plugging in, the first GFI tripped, so I moved it to a 3rd location, then it tripped. As this point I was running out of options so I split the power to all 3 GFI outlets. This got me through the night, but one of them tripped during the break (thank goodness).

I was told by management that no one else has had this problem, and I advised them that neither had I. The venue also has a 220 GFI outlet at the stage area, and I believe the other sound providers have used that, but I'm not sure.

Any ideas or suggestions? The outlets tested good with my cheap receptacle tester (I know, I need better). I'm thinking about getting a distro box for myself, but I need to do some reading.

I've bookmarked TJ's page on stage power BTW, need some time to go over it.

You mentioned power strips. Most have surge suppressors (that donít do much) but do leak some current. Perhaps your power strip is leaking just under the trip current and adding the band gear (which also may leak some) is what is getting you?

I opened up some of mine and snipped out anything that was not an outlet.



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Tim McCulloch

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Re: GFI's Tripping
« Reply #2 on: October 29, 2017, 11:47:41 pm »

Only my second post on this Power forum and I don't know much about power, so bear with me.

Yesterday I did a show at a brewery taproom. My system is a small, active SRX speaker over sub per side, and 4 Yamaha DSR monitors. The board is a Mackie DL. While setting up, I ran my power strips around the stage coming from a dedicated GFI outlet. While I was turning boxes on, the GFI tripped. Next I split my stage power to another GFI box and all was good. Later as the bands were showing up and plugging in, the first GFI tripped, so I moved it to a 3rd location, then it tripped. As this point I was running out of options so I split the power to all 3 GFI outlets. This got me through the night, but one of them tripped during the break (thank goodness).

I was told by management that no one else has had this problem, and I advised them that neither had I. The venue also has a 220 GFI outlet at the stage area, and I believe the other sound providers have used that, but I'm not sure.

Any ideas or suggestions? The outlets tested good with my cheap receptacle tester (I know, I need better). I'm thinking about getting a distro box for myself, but I need to do some reading.

I've bookmarked TJ's page on stage power BTW, need some time to go over it.

Carefully read Rob's post.

He's spot on about both leaky power strips (the MOV components work by shorting the hot to ground) and the *cumulative* effect of leaky devices - guitar/bass amps, home made extension cords (many but not all, in my experience), etc.  If the power strip leaks 2 or 3 mA, the GFCI is remains on; if a Fender Twin leaks 4 mA the GFCI stand on; if you plug the Twin into the power strip, the GFCI will trip.

Were all the outlets in the performance area on GFCI?
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Mike Sokol

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Re: GFI's Tripping
« Reply #3 on: October 30, 2017, 12:23:13 am »

If the power strip leaks 2 or 3 mA, the GFCI is remains on; if a Fender Twin leaks 4 mA the GFCI stand on; if you plug the Twin into the power strip, the GFCI will trip.

+1   A power strip can leak up to 3mA to ground and still be in UL compliance. So even two power strips plugged into the same GFCI receptacle can get to the trip threshold. And old tube amps with ageing power transformers or stinger caps can leak just as much. Also as noted, these leakage currents are additive, so tripping a GFCI with several backine amps and a few surge strips on it is almost a guarantee.
« Last Edit: October 30, 2017, 06:40:25 am by Mike Sokol »
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Lyle Williams

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Re: GFI's Tripping
« Reply #4 on: October 30, 2017, 01:43:46 am »

A leak or just an additional neutral-ground connection somewhere.
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Mike Sokol

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Re: GFI's Tripping
« Reply #5 on: October 30, 2017, 06:46:51 am »

A leak or just an additional neutral-ground connection somewhere.

Another thing that will trip a GFCI instantly is swapped neutral/ground wiring. This happens more often than you might think even in new construction.

John Roberts {JR}

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Re: GFI's Tripping
« Reply #6 on: October 30, 2017, 10:01:59 am »

You mentioned power strips. Most have surge suppressors (that donít do much) but do leak some current. Perhaps your power strip is leaking just under the trip current and adding the band gear (which also may leak some) is what is getting you?

I opened up some of mine and snipped out anything that was not an outlet.



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+1

I've told this story before, not only do cheap power strip have leaky protection (?) devices, but if you plug into a mains power drop with an open safety ground (like most of my house), the power strip leakage can energize the chassis grounds of all the equipment plugged into that same power strip. 

Generally harmless low single digit mA leakage, but enough to feel if sensitive, and measure if you look for it.

JR
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Steve Garris

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Re: GFI's Tripping
« Reply #7 on: October 30, 2017, 01:00:57 pm »

Carefully read Rob's post.

He's spot on about both leaky power strips (the MOV components work by shorting the hot to ground) and the *cumulative* effect of leaky devices - guitar/bass amps, home made extension cords (many but not all, in my experience), etc.  If the power strip leaks 2 or 3 mA, the GFCI is remains on; if a Fender Twin leaks 4 mA the GFCI stand on; if you plug the Twin into the power strip, the GFCI will trip.

Were all the outlets in the performance area on GFCI?

Yes, all 3 were GFI - a newer looking installation.

Can I measure this with a meter?

I've use the same 5 power strips at every gig for the past 4 years without problems. I do a summer concert series and run them from (1) 20 amp GFI outlet - supplying power for the PA, some lights and backline, all from one receptacle. Two of my strips are the metal Furman boxes, and 3 are some nice, black strips that have a long heavy gauge power cable. I would suspect these could be a possibility.

At this venue, the fist GFI tripped before the band arrived. The backline did consist of some very old looking tube amps though.
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John Roberts {JR}

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Re: GFI's Tripping
« Reply #8 on: October 30, 2017, 01:40:17 pm »

Yes, all 3 were GFI - a newer looking installation.

Can I measure this with a meter?

I've use the same 5 power strips at every gig for the past 4 years without problems. I do a summer concert series and run them from (1) 20 amp GFI outlet - supplying power for the PA, some lights and backline, all from one receptacle. Two of my strips are the metal Furman boxes, and 3 are some nice, black strips that have a long heavy gauge power cable. I would suspect these could be a possibility.

At this venue, the fist GFI tripped before the band arrived. The backline did consist of some very old looking tube amps though.
I would be tempted to just clip out the protection devices inside all the cheap power strips. I removed them from mine that were causing measurable leakage.

In principle you could open up the ground circuit and put a VOM mA in series with the ground lead of an empty power strip. These leakage currents will be additive, so several together could easily trip a GFCI. Of course be careful making measurements around mains power.
 
JR
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Stephen Kirby

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Re: GFI's Tripping
« Reply #9 on: October 30, 2017, 05:32:25 pm »

When you say things were being plugged in, does this include bass amps and keyboards being plugged into the PA?

This may be an opportunity for a poor man's distro.  I do a couple outdoor venues each year where I have to run from GFCI Edisons.  Run things back to my PMD and never had any trip issues.  I even have separate GFCIs on my backline stringer so there are two in series with various tube amps plugged into them.  Still no issues.
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