The "I Hate GFCIs" thread

Frank Koenig

Frank Koenig

Sophomore
Mar 7, 2011
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Palo Alto, CA USA
www.dunmovin.com
I thought I'd split this off from Jack's legitimate issue in Varsity so that we can go way off topic.

First off, GFCIs are fundamentally good things. They save lives, especially in home, construction, and farm situations with poor maintenance, dodgy grounds, and people who insist on using hair dryers in the bathtub. But they can also be a major source of irritation.

In addition to the spontaneous combustion problem I alluded to in the other thread, I had another failure of one on the output of a 400W, 12VDC-to-120VAC inverter that we were to use to power a rotisserie to roast a rabbit over an open fire. When the inverter output was dead my heart sank but I opened it up to find ample 120 AC on the wires going into the GFCI. (Always carry a meter.) We ripped out the offending GFCI, wrapped the wires around the prongs of the plug, and the rabbit rotated. Unfortunately, we hadn't tied the rabbit's limbs very well and they started to flail grotesquely, which caused the by then quite drunk dinner guests to have an uncontrollable fit of giggles. We finished the rabbit on a Webber and it tasted more-or-less like chicken. But that's not really a GFCI problem.

GFCIs, at least older ones, can be tripped by inductive turn-off transients. Often, at home, when I turn off the MIG welder, which is an older one with a 60 Hz transformer the size of a small watermelon, GFCIs all over the house trip. The shop, where the welder is, is on a separate feeder, but no matter. It may be tripping my neighbors' GFCIs for all I know.

The GFCIs you buy now come with an LED on them. This seems like a good idea -- you can find them in the dark. Except that when they trip and make the lights go out, which is the one time you'd really like to find them, the LED goes out too.

--Frank
 
Re: The "I Hate GFCIs" thread

I recently put GFCI outlets on a bathroom and kitchen outlet since discovering that 3 wire outlets in my house do not mean there is actually a ground connection. I feel a little silly now about using 2 to 3 wire plug adapters and actually bothering to connect the faceplate ground screw to nothing... :-(

I bought the cheapest made in China GFCIs I could find so it will be a horse race to see if I outlast them (I bought a package of three so have one back-up in reserve).

I am an advocate of GFCI for live sound use, but appreciate that they can easily become yet another point of failure. Perhaps we can put them into pluggable modules so they can be easily swapped in the field should they become the problem instead of preventing the problem.

JR
 
Re: The "I Hate GFCIs" thread

I think the newest ones are required to trip on a power outage? I have a 100' 12 gauge extension with one in-line and a windows AC unit with one in the plag that both do that. NFI why the AC has one :?~:-?~:???: ?
 
Re: The "I Hate GFCIs" thread

Jordan Wolf said:
They do sell them - I have one that I take with me for all outdoor shows. It's a little box that has plugs right into a wall outlet and I then plug into it with my gear.
Click to expand...

Not the first time the ancients stole one of my ideas. :-) That said for $60 I would be inclined to roll my own. It seems a simple junction box break out with a couple outlets. Perhaps carry a spare break out in case if failure.

Another option is to buy a power strip with GFCI built in. If I was the meat on stage I'd carry my own.... But I'd never be the talent for so many reasons. :-)

JR
 
Re: The "I Hate GFCIs" thread

'' GFCIs, at least older ones, can be tripped by inductive turn-off transients. Often, at home, when I turn off the MIG welder, which is an older one with a 60 Hz transformer the size of a small watermelon, GFCIs all over the house trip. The shop, where the welder is, is on a separate feeder, but no matter. It may be tripping my neighbors' GFCIs for all I know. ''

I just kinda like this statement on the welder. I had a old hobartt tig, that sucker dimmed the lights in my house and the next doors neighbors. Then I finally cooked the 25 kva pad mount transformer on day.
 
Re: The "I Hate GFCIs" thread

I'm sure I've been saved from many a deadly shock both in my day job (gas, water and electricity mixed in the wrong way can make for ugly happenings!) and gigs IMO a lot of people will pull them from a circuit rather than test them 1st ignore the warning if you must but if that device tested good then there is a problem somewhere just don't complain to me if you get zapped G
 
Re: The "I Hate GFCIs" thread

Frank Koenig said:
I thought I'd split this off from Jack's legitimate issue in Varsity so that we can go way off topic.

First off, GFCIs are fundamentally good things. They save lives, especially in home, construction, and farm situations with poor maintenance, dodgy grounds, and people who insist on using hair dryers in the bathtub. But they can also be a major source of irritation.
Click to expand...

Hm, those sorts of conditions sound suspiciously like quite a few dodgy performance venues...


GFCIs, at least in the US, must trip with 3-5mA difference between line and neutral. As this is typically measured with a current transformer, any instantaneous difference that exceeds the threshold will cause the GFCI to trip. In practice, this means that devices with reasonable quantities of energy storage (e.g. motors) will trip the GFCI.

Most regulatory agencies allow for some current to flow to the ground pin in electrical products, but this is limited to a maximum of 3mA (often lower). So a properly functioning piece of electrical equipment will not trip a properly functioning GFCI, but it is possible that multiple pieces of equipment with earth leakage currents at the high end of the allowed range will.
 
Re: The "I Hate GFCIs" thread

Rob Timmerman said:
Hm, those sorts of conditions sound suspiciously like quite a few dodgy performance venues...


GFCIs, at least in the US, must trip with 3-5mA difference between line and neutral. As this is typically measured with a current transformer, any instantaneous difference that exceeds the threshold will cause the GFCI to trip. In practice, this means that devices with reasonable quantities of energy storage (e.g. motors) will trip the GFCI.

Most regulatory agencies allow for some current to flow to the ground pin in electrical products, but this is limited to a maximum of 3mA (often lower). So a properly functioning piece of electrical equipment will not trip a properly functioning GFCI, but it is possible that multiple pieces of equipment with earth leakage currents at the high end of the allowed range will.
Click to expand...

While regulations may allow for up to 3 mA leakage probably based on the human safety threat involved, I would expect most gear in good working order to exhibit leakage near zero.

In bench testing I would consider any measured impedance between ground and either other mains lead a potential problem warranting closer inspection.


JR
 
Re: The "I Hate GFCIs" thread

frank kayser said:
Yeah. I got one like that.. Seemed a good idea. Too bad the GFCI failed.
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If a GFCI power strip is too pricey to consider disposable, perhaps DIY a breakout built into a metal junction box sized for two duplex outlets. One GFCI can daisy chain to protect a second standard outlet. "When" the cheap GFCI outlet fails, just replace. Maybe build a few of these at the same time and keep one spare handy to swap out in the heat of battle or confirm that there really is a ground fault when one indicates. While a VOM could probably quickly identify which product is tripping the GFCI.

JR
 
Re: The "I Hate GFCIs" thread

John Roberts said:
If a GFCI power strip is too pricey to consider disposable, perhaps DIY a breakout built into a metal junction box sized for two duplex outlets. One GFCI can daisy chain to protect a second standard outlet. "When" the cheap GFCI outlet fails, just replace. Maybe build a few of these at the same time and keep one spare handy to swap out in the heat of battle or confirm that there really is a ground fault when one indicates. While a VOM could probably quickly identify which product is tripping the GFCI.

JR
Click to expand...
Good suggestions.
Maybe I'll just have OA Windsor build one in his rubber boxes. Powercon on either side and Voila! If (when) GFI fails, just swap out the junction box, and then replace the bad GFI back in the shop.
 
frank kayser said:
Good suggestions.
Maybe I'll just have OA Windsor build one in his rubber boxes. Powercon on either side and Voila! If (when) GFI fails, just swap out the junction box, and then replace the bad GFI back in the shop.
Click to expand...

I have boxes with powercon in and out and one box has a GFI in it when I need it. If I make it the first box in the stage stringer then it is all protected.


Sent from my iPad HD
 
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