Venue outlets have open ground. What does that mean?

[Old Garage-Bander]

Um, if I understand the question properly, any protective equipment would be at the outlet. So yes, the amp. But, this conversation has evolved beyond my comprehension.

I think it was just a case of someone with little or no knowledge of electricity (to no fault of his own) throwing stuff at the wall to see what sticks. It may seem beyond comprehension, but so does a lot of stuff in the beginning. Asking those questions may seem irrelevant. But if we don't ask, we never learn anything.

 

[Old Garage-Bander]

Well, we have a lot of old houses, and mice are incontinent, and cause dust by making nests. It really does happen... Ideal methods based on codes can define some acceptable threshold, but thresholds can be crossed.

So now we blame the mice? What's next, Einstein's definition of quantum entanglement? I'm sorry but this has gone way off the rails? Sounds like you need an electrician and an exterminator.

 

[TomB]

Um, if I understand the question properly, any protective equipment would be at the outlet. So yes, the amp. But, this conversation has evolved beyond my comprehension.

A GFCI would be either at the outlet you’re using, or another outlet on the same circuit. It might still show an open ground, but if one is present you can at least test that it’s operating properly. We learned in very early posts that portable GFCI’s are available if you want to be sure there’s one in the circuit you’re using. If it were to trip, I’m not sure what you’d do about the show in progress, but at least you’d know you had a level of protection in place.

 

[kittywithabanjo]

Its great you carry a tester with you, I carry one in my kit as well, I actually dont use it in most bars but for outdoor gigs I am always checking whatever they send me for power.

 

[groovepump]

Meaning then that your iso transformer breaks the ground?

At the load side, yes. No PE connection. However, the receptacles on the load side have their gnd connections tied together, but not connected to PE.

 

[Smallmouth_Bass]

A GFCI would be either at the outlet you’re using, or another outlet on the same circuit. It might still show an open ground, but if one is present you can at least test that it’s operating properly. We learned in very early posts that portable GFCI’s are available if you want to be sure there’s one in the circuit you’re using. If it were to trip, I’m not sure what you’d do about the show in progress, but at least you’d know you had a level of protection in place.

But, the only reason a GFCI cord would trip is if there was a dangerous situation, right? So, if I am understanding correctly, you wouldn't want the show to progress if that were the case.

 

[SoCal80s]

But, the only reason a GFCI cord would trip is if there was a dangerous situation, right? So, if I am understanding correctly, you wouldn't want the show to progress if that were the case.

Well, it could also trip if the GFCI itself was faulty. If you get a quality one then that is unlikely, but if you're a bargain shopper then ??

 

[Old Garage-Bander]

But, the only reason a GFCI cord would trip is if there was a dangerous situation, right? So, if I am understanding correctly, you wouldn't want the show to progress if that were the case.

They trip because of a fault between you and the GFCI protected outlet. Not necessarily that there is a fault between the protection outlet and the rest of the venue. Though that can be a contributing factor. Bottom line, don't trust that any or all safety measures will guarantee 100% safety, 100% of the time. And if stupidity or carelessness are involved, those odds drop sharply.

 

[TomB]

Well, it could also trip of the GFCI itself was faulty. If you get a quality one then that is unlikely, but if you're a bargain shopper then ??

Exactly! GFCI devices come in a range of quality and vary a surprising amount in accuracy. I have one in my kitchen that triggers almost every time you unplug something quickly! Shop carefully if you go this route. Maybe @Tommy Sparks has a product suggestion?

 

[Old Garage-Bander]

Well, it could also trip of the GFCI itself was faulty. If you get a quality one then that is unlikely, but if you're a bargain shopper then ??

A false trip is better than not tripping on a fault. I suppose either failure mode is possible. No more or less though than the odds of any manufactured device having been built faulty, or developing it's own fault over time.
It's a good idea to use the self test feature on GFCI outlets, prior to use. That won't predict the future, but if it fails to trip when you test it, beware.

My Three-light plug tester not only checks for correct wiring, but also shows line voltage and has a built in GFCI test function. That way if I'm at the end of a long extension cable, I can check things where the rubber hits the road.

 

[reverendboom]

Ok, here's one. It's a nice document too:
http://https..pdhonline.com/courses/e321/e321content.pdf

The problem is that terminology is a bit iffy, and the doc makes clear that GFCI and RCD and RCCB are considered synonymous. The detailed schematics and text are clearly what Brits will recognise as an RCD or RCCB. They don't refer to ground.

In the case of solar installs, and the main GF detector in a building, they do refer to one single ground, as an extension of the normal RCD business. Well, they probably should because it's important for a case where monitoring of a ground flow return can detect a fault outside the local subcircuit.

Where the term GFCI really is a synonym for RCD any number can be used, they won't upset a real ground fault detector because they don't have a ground link that might share the leakage current between all such devices, likely compromising the ability of the main one to detect the fault current.

It may well be that solar installs, which can have a thousand volts of DC in an 'upstream' array of panels, makes the single ground link mandatory so nothing compromises it, but a similar thing might make large venues safer because it could reduce the risk of false triggers caused by differences due to insulation leaks in long conductors.

So long as the extra devices are all RCD, truly having no ground link of their own, then all's good, and you get local indication of a fault too which could reduce downtime for a show. If a local RCD trips fast enough, a main GFCI with a ground link might not open the circuit, but in this case it wouldn't have to, which further increases reliable indication of where the fault is, so the more RCD's the better.

Link won't open. BTW, I'm not saying that a ground is unnecessary in a safe circuit, only that it is not necessary for a GFCI to work.

 

[Lostgallifreyan]

Link won't open. BTW, I'm not saying that a ground is unnecessary in a safe circuit, only that it is not necessary for a GFCI to work.

Sorry about that, I think when I edit, a web filter on my system mangles the URL's 'https' bit. Thsi might stay intact if I leave the post alone after first send.

https://pdhonline.com/courses/e321/e321content.pdf

I did a bit of reading elsewhere in the last hour of three, and there's some consensus in UK circles that 'GFCI' is misleading because the ground fault is assumed to cause the differential, while its lack of ground reference means it must be agnostic of where the fault current actualyl goes!

On the upside, it turns out that the 'misleading' term in the US actually defines what the UK bods call a 5mA trip RCD, so it's the right thing to use, whatever it's called. I think the distinction may be important when the more specialised form becomes popular, the one that monitors ground and can detect faults outside the protected load circuit.

----

I also did a bit of reading on mice and their pee and their dust causing fires. It IS a 'thing', it really is, but apparently the 'AFCI' (arc fault interruptor) is the thing to use if a small hazardous arc in inaccessible locations is likely to arise. At this point I'll bow out of the thread, I said plenty now, don't want to overdo it...

 

[MidlifeBeginner]

I think we need to summarize the good insights from this thread into Electrical Safety Guidance for Bands.

• Don't create your own power cords. Buy commercial off the shelf. Pay attention to current/wattage rating.
• An outlet tester or surge protector with indicator lights will warn you about reversed hot or missing ground.
• Surge protectors only protect your equipment if they have a ground. Surge protection protects equipment, not you.
• A power conditioner or UPS might be desired to protect equipment or reduce noise.
• Your own GFCI is recommended to have along for outdoor gigs, or where drinks might be spilled on stage. A GFCI near you is better for protecting against electrocution than one farther down the wire.
• It is best to have all gear on the stage connected to the same grounded circuit. Ground differences cause noisy ground loops, and can shock you.
• If not using a wireless system, your guitar grounds you. Beware that PA systems might be on a different ground. Ground difference between your guitar and a mic can shock you. Ground lift on XLR systems are meant to cut noise, not protect you.

Those that are more in the know than I am can edit this, and make it a good reference.

 

[TomB]

Sorry about that, I think when I edit, a web filter on my system mangles the URL's 'https' bit. Thsi might stay intact if I leave the post alone after first send.

https://pdhonline.com/courses/e321/e321content.pdf

I did a bit of reading elsewhere in the last hour of three, and there's some consensus in UK circles that 'GFCI' is misleading because the ground fault is assumed to cause the differential, while its lack of ground reference means it must be agnostic of where the fault current actualyl goes!

On the upside, it turns out that the 'misleading' term in the US actually defines what the UK bods call a 5mA trip RCD, so it's the right thing to use, whatever it's called. I think the distinction may be important when the more specialised form becomes popular, the one that monitors ground and can detect faults outside the protected load circuit.

----

I also did a bit of reading on mice and their pee and their dust causing fires. It IS a 'thing', it really is, but apparently the 'AFCI' (arc fault interruptor) is the thing to use if a small hazardous arc in inaccessible locations is likely to arise. At this point I'll bow out of the thread, I said plenty now, don't want to overdo it...

Of course, no one’s ever seen a mouse in a music venue, have they? All the rodents I’ve seen there were MUCH bigger .

 

[Lostgallifreyan]

Of course, no one’s ever seen a mouse in a music venue, have they? All the rodents I’ve seen there were MUCH bigger .

We must be nice to our rattussy friends, as any Stranglers fan can attest. At least the little buggers aren't incontinent...

 

[seamonkey]

Before even getting to the gig, put it in the contract.
Give a link and model # of the outlet tester and let the people who are coordinating the show. Tell them that when you arrive and will use such a test on every outlet and it has to pass before you will plugin.
Also put in the amperage of the breakers you need, and access to the breaker panel.

No such risking such a simple safety practice at any place you play.

 

[reverendboom]

Sorry about that, I think when I edit, a web filter on my system mangles the URL's 'https' bit. Thsi might stay intact if I leave the post alone after first send.

https://pdhonline.com/courses/e321/e321content.pdf

I did a bit of reading elsewhere in the last hour of three, and there's some consensus in UK circles that 'GFCI' is misleading because the ground fault is assumed to cause the differential, while its lack of ground reference means it must be agnostic of where the fault current actualyl goes!

On the upside, it turns out that the 'misleading' term in the US actually defines what the UK bods call a 5mA trip RCD, so it's the right thing to use, whatever it's called. I think the distinction may be important when the more specialised form becomes popular, the one that monitors ground and can detect faults outside the protected load circuit.

----

I also did a bit of reading on mice and their pee and their dust causing fires. It IS a 'thing', it really is, but apparently the 'AFCI' (arc fault interruptor) is the thing to use if a small hazardous arc in inaccessible locations is likely to arise. At this point I'll bow out of the thread, I said plenty now, don't want to overdo it...

OK, I think we are in agreement as to the current situation. When the more specialized form becomes more popular the ground will be needed as it monitors that.

BTW, I have a great rat story. I was trouble shooting a kitchen range that had stopped working. it had tripped the breaker and then nothing. Pulled out the range...no power. Checked the breaker and power there. So I turned off the breaker opened up jacket right where the line dropped into the wall did the pin thing and had the breaker reenergized. 240vAC. Opened up the wall to find a rat had managed to chew through and get both hots in his teeth at the same time. fried the poor little guy and blew the wires apart. That must have created one heck of a plasma cloud. I don't know why it didn't start a fire.

 

[Smallmouth_Bass]

Of course, no one’s ever seen a mouse in a music venue, have they? All the rodents I’ve seen there were MUCH bigger .

I've seen a squirrel in a venue! It has since been torn down and a condo complex put in its place.

 

[TomB]

I've seen a squirrel in a venue! It has since been torn down and a condo complex put in its place.

Ah! I bet there were a few “open grounds” there too .

 

[Michael Eisenman]

A false trip is better than not tripping on a fault. I suppose either failure mode is possible. No more or less though than the odds of any manufactured device having been built faulty, or developing it's own fault over time.
It's a good idea to use the self test feature on GFCI outlets, prior to use. That won't predict the future, but if it fails to trip when you test it, beware.

My Three-light plug tester not only checks for correct wiring, but also shows line voltage and has a built in GFCI test function. That way if I'm at the end of a long extension cable, I can check things where the rubber hits the road.

Maybe you specified earlier which advanced tester you are using, but can you tell us (again)?