Venue outlets have open ground. What does that mean?

[MultiScaleMale]

Does a GFI in a box that you plug your guitar into exist? Would it even make sense? I guess it wouldn't do anything about your mic and wireless is probably the best way to handle this scenario, but wireless units have drop outs. A circuit breaker on your pedal board would be nice if you're touring and hitting unknown electrical on any given day.

 

[MidlifeBeginner]

must be protected here in australia

Don't let higher levels of enforcement fool you. If you go play a gig in a farmer's barn, you better check the outlet. Bad wiring exists somewhere in your country. Over years, connections can work lose even on properly wired equipment. Outdoors, the daily temperature swings loosen screws.

 

[crazyBassClown]

Does a GFI in a box that you plug your guitar into exist? Would it even make sense?

If you plug the amp into a GFCI then anything plugged into that amp is protected from power getting out of it.
Ditto if the PA is in a protected circuit anything coming from a mic would be protected.
An unprotected PA with a fault could shock you via the mic through your guitar but not trip a GFCI your amp was plugged into though.
This is why it seems so odd to me to put a whole lot of GFCI's throughout a house on selected outlets instead of a single unit on the mains feed into the house. I guess the benefit is when you have a dodgy toaster it only trips that circuit instead of your whole house though.

 

[groovepump]

Be careful that the isolation transformer is the type that breaks the ground connection in addition to the isolation. If not, it may not be protecting YOU as well as you think. The purpose of most isolation transformers is to protect other equipment. And since people use that equipment, the ground, by law/code needs to carry through.

I'm good. The grounding is correct. But I appreciate your adding your comment, as I made no mention of the grounding. Thanks.

 

[Geogio]

Well, now I'm worried about something I wasn't worried about before I saw this thread existed.
(not complaining)
I can imagine some of the places we could play aren't up to code.

They only have to be up to code when they were built. Any later Including aslteration are also inspected. You would think there would be a little buy-in by the owner for especially if he wants to bring bands in there. They could run an entirely separate circuit if they really wanted to - out of a breakout panel all within code.

 

[ArtechnikA]

ummm. I'm still on the first page but GfCI's do not require a ground to work. What they do is monitor the current between the hot and neutral wires and if there is a drop on the neutral (indicating a fault to ground) it trips.s

Thanks; I learned something today.

 

[Lostgallifreyan]

Does a GFI in a box that you plug your guitar into exist?

No such animal, but that's a very good question because a widget that treats the cause of trouble at the point of their own use is the sort of thing people would actually use, if they could get one.

The guitar itself might be eliminated from the risk by the same means that MIDI inputs do it, with an optoisolator. There are variants that can take a linear signal with enough dynamic range for an active bass output. Passive bass is the problem, because the device would then be more complex and have to be designed specifically for guitars, and have its own battery to drive the isolator's internal LED. Wireless signalling might work more conveniently, but with risk of losing signal. It's usually better to protect the amp and any effects with a very sensitive residual current breaker in one supply common to them all.

Also, it won't solve the wider problem. A person might have a safe guitar and then get harmed by leaning to grab a mic stand to steady themselves on a crowded stage. This is why there really needs to be a method that works on the entire local supply network (one of several circuits in one venue, you wouldn't want lights to fail when a power socket failed). It's cheaper that way too. The main problem with fixed RCD's is they trip at 25 mA or more, and 15 to 20 can sometimes kill.

There is likely no risk in having your own RCD protection when existing RCD or GFCI protection exists upstream, but if your RCD keeps tripping out, then that means trouble elsewhere, so it's a good warning device if nothing else. If a small 'personal' RCD is added, it should trip at just 5 mA, that way it is extremely likely to prevent death even in a worst-case situation.

 

[Lostgallifreyan]

...it seems so odd to me to put a whole lot of GFCI's throughout a house on selected outlets instead of a single unit on the mains feed into the house. I guess the benefit is when you have a dodgy toaster it only trips that circuit instead of your whole house though.

I think the main reason is to prevent fire in unsupervised fixed installs, because it often takes only a few tens of mA at AC line voltage to do that if water and wood can be heated enough to support an arc, causing carbonisation of the wood. Also, if there is a sudden high current fault, the RCD or GFCI will act a lot faster than a standard breaker that is only intended to replace a fuse, and it will open both live and neutral too.

In my post just above this one, I mention the 5mA trip type of RCD, which is what is best used as a spot fix when prevention of electrocution is the main need.

 

[crazyBassClown]

I think the main reason is to prevent fire in unsupervised fixed installs, because it often takes only a few tens of mA at AC line voltage to do that if water and wood can be heated enough to support an arc, causing carbonisation of the wood.

I would think an outlet mounted RCD/GFCI provides virtually no protection for this as it would be an internal wiring problem mostly, and any current arcing from active to neutral doesn't trip it at all.

 

[Rip Van Dan]

That’s shocking !!!

 

[Lostgallifreyan]

I would think an outlet mounted RCD/GFCI provides virtually no protection for this as it would be an internal wiring problem mostly, and any current arcing from active to neutral doesn't trip it at all.

True, but current directly between L and N is interpreted as a normal load. I was thinking of any earth leakage current, because that's where a fire risk more likely exists and the resulting difference caused in the L and N lines is then going to trip it.

The only problem is it's too high a trip to protect against electrocution because fixed installs, outside medical setups, rarely trip as low as 5mA. I've seen metal clad fittings that do, but at £30 a time or more, it's not likely to prompt a lot of people to get one. The small IEC-connected Xerox ones found on Ebay are a better way, much cheaper (in an awkward shape), but they come with irritating labels implying they must only be used on Xerox gear! As if a 5mA current leak ever has a strictly proprietary interest!

 

[fishdude101101]

The “rag wire” is a problem and should be replaced with emt conduit or three wire romex if your local code allows.
The 2 wire in metal jacket bx is ok if all the screws are tight. The jacket is the ground.

The issue I was pointing out with the metal jack on one particular run isn't grounded to anything. The outlet tester is giving a false sense of security. That metal jacket going to an ungrounded box isn't doing anything really.

I'll replace it one day. It is in decent condition.

 

[Paul New]

I would think an outlet mounted RCD/GFCI provides virtually no protection for this as it would be an internal wiring problem mostly, and any current arcing from active to neutral doesn't trip it at all.

A dead short should trip the breaker pretty quick. GFCIs are designed to open the circuit on a high impedance imbalance that a breaker won’t see.

You can use, instead of GFCI outlets, GFCI breakers in the distribution panel. They only open the Line conductor, and not the neutral though. In any case, a GFCI is not a substitute for a grounded circuit.

We all rely on electrical code compliance to keep us safe, and all of the situations those codes are supposed to prevent were discovered by the trial and error method. Quite a few of the errors were tragic.

 

[Turnaround]

A rubber mat would help if the person would otherwise provide the unwanted path to ground and they only come in contact with one "hot" piece of gear, like the mic. It won't help if there is a wiring problem between the mic and your amp, and you touch the mic, while also touching your strings.

We had a singer in the band a number of years ago who just wouldn't pay attention. We played the same venue regularly, and every time he would complain about getting a shock from the mic. And every time it happened I told him not to plug his guitar amp into the outlet on the other side of the stage, but into the same power box we were using for the PA. Every time he would grudgingly move his amp plug to the power bar and the problem went away. And the next time we played the same venue he did the same thing. I tried explaining that there was a different ground level on the circuit he was plugging into, but I guess he didn't understand. Maybe he got shocked once too often and it addled his brain.

 

[crazyBassClown]

The issue I was pointing out with the metal jack on one particular run isn't grounded to anything. The outlet tester is giving a false sense of security. That metal jacket going to an ungrounded box isn't doing anything really.

If the tester is showing it as grounded then the ground pin is either grounded or connected to neutral somehow. Merely connecting it to some ungrounded metal would not make it show a valid ground.

You can use, instead of GFCI outlets, GFCI breakers in the distribution panel.

I am aware. In australia Distribution panel protection is the legally required type.

 

[fishdude101101]

If the tester is showing it as grounded then the ground pin is either grounded or connected to neutral somehow. Merely connecting it to some ungrounded metal would not make it show a valid ground.


I am aware. In australia Distribution panel protection is the legally required type.

But it is doing exactly that. Not connected to neutral, just a limitation of cheap outlet testers. This why I've replaced many of my u grounded outlets with gfci.

StackPath

 

[crazyBassClown]

But it is doing exactly that.

Based on what? Have you actually measured the resistance to ground from that outlets ground pin?

 

[INSUB]

Quite frankly folks. I’m appalled at the number of responses that want to call in a governmental agency.

The authorities are required as a last-ditch effort to force compliance. This method should absolutely be used against any entity disregarding life safety. Electrical systems are the most likely of any building system to cause a fatality.

I always bring a Furman power strip w surge protection, and the only thing I plug in is my own amp and pedals (and I don't sing): (Furman SS-6B Surge Block). Does that offer protection in an open ground situation like this venue has?

NO. And whatever protection you thought you were getting for your equipment connected to it probably doesn't work either without the ground.

It means the wiring is old (2-wire), and there's no earth ground for the circuit. If there's a circuit breaker, you should be okay.

ABSOLUTELY NOT! A circuit breaker is unlikely to trip promptly during a ground fault where there is no equipment ground. The equipment ground is multi-purpose. To create an alternate path to ground in case the neutral is broken and for bonding equipment chassis so that there is a low impedance path is back to the source, which in turn causes high enough current to flow through the circuit breaker to cause it to trip quickly. Even that is still not quickly enough to prevent an electrocution. Which is exactly why GFCI's were invented.

NO! A circuit breaker is designed to protect the wiring in the wall from overheating due to more current than the wiring can take. That's about fire safety, not people safety. You can be well on your way to the morgue before that breaker ever trips.

Mr Garage-Bander is correct here. Use of fuses and circuit breakers were intended as equipment protection. Their only life protection was to prevent the building from catching on fire and burning people to death. Which still happens a lot to this day.

The current path is usually not between the mic and the floor, so rubber mat probably won't help in most situations. ...

AFAIK the problem is usually between the chassis of an amp and the chassis of the mixer.

This is correct as to why an electrically insulated mat would not protect you. One night the band after us was playing and the singer was shocked after putting on a guitar which he hadn't played during previous songs. The microphone was electrified, but he wasn't shocked until his fingers were touching the grounded strings of his guitar.

Circuit breakers protect the wire from overheating and starting the building on fire. They do NOT protect you against electrocution - the amount of current that will kill you will not trip a breaker or blow a fuse.

This statement is absolutely true.

Word of caution about outlet testers. Sometimes "grounded" isn't "grounded"

Let me give you a practical example. Bought an old house last year. A couple of circuits are old "BX" metal clad cable with only 2 conductors, no dedicated groundwire. 2 prong outlets. I replaced them with 3 prong outles but there is obviously nothing to hook the ground on the receptacle to. But they have metal outlet boxes and metal cladding all they way back to the breaker box so they read as "grounded" with an outlet testers, even the one that is only metal clad for about 10 feat to a metal junction box and then is "rag wire" back to the breaker box. Hope that makes sense. I know two fingers was an electricians so he might be able to explain a bit better.

This is only partially correct, IMO. As another argued, if the tester shows grounded then it is in fact grounded (or connected to the neutral which is grounded). The metal box through the connector and BX metal jacket is continuous back to the panel which is bonded to the earth ground. However, use of BX jacket as equipment ground is a NEC violation in the USA because the BX jacket is not UL listed for use as an equipment ground. And, since BX cable is no longer manufactured, it will never be tested by UL. In certain cases, metallic conduit is approved for use as an equipment ground so long as is electrically continuous back to the source. I don't believe there is any proof that the BX jacket is not an effective equipment ground path. It's just not an approved method.

On at least one of those runs it is not really grounded, not even close to properly. The metal cladding run about 10 feet to a metal junction box. From the junction box to the breaker box it is cloth covered wire with no ground.

There is a ground, it's the metal jacket itself. It is not "Proper" because the method is not approved. But it's unclear whether the BX jacket is effective.

Yeah, that'll get you rebooked there. More likely cause the place to get shut down. If the OP reported it to the owners 10 years ago and it didn't get fixed, even with new owners, that means it was too expensive.

In most cases citations are allowed sufficient time to be remedied before fines are levied. This is true with OSHA and most building enforcement. OSHA refers to acts as willful violations when they know that the employer was aware and purposefully chose to disregard life safety.

Don't do that! Seriously... Leave it set to make the proper ground connection unless totally sure that it's only acting in the audio ground, and the electrical ground is hardwired and links to a properly grounded outlet too. 'Ground lift' is a Seriously Bad Idea, it should never have been invented.

There's a document by Rane called "Grounding and Shielding Audio Devices" that goes into this at length, but its an easy read, and has influenced the better habits of modern audio gear makers.

I am not familiar with the Rane document you mention. But if you are referring to the ground lift switch for XLR cable connections that has nothing to do with shock protection. Signal cable drains should only have connection to earth at one end. From mixer to microphone, there is no issue because the mic is not grounded. But mixer to bass amp DI could cause a ground loop due to both devices being connected to ground via the mains.

Because the US is extremely relaxed about Electrical safety

All outlets (and i think actually all circuits) must be protected here in australia , and AFAIK a deathcap amp would never have been approved here, even back in the day.

I wouldn't call electrical safety in the USA as lax, however enforcement is another topic. All NEW residential outlets are required to be either arc-fault or GFCI protected, or both in the latest NEC. Not all jurisdictions in the USA adopt the latest NEC into law. And all existing installations are grandfathered to the version of the code that was applicable the year they were installed. That being considered, you can imagine how difficult it might be to determine violations for electrical systems.

This is why it seems so odd to me to put a whole lot of GFCI's throughout a house on selected outlets instead of a single unit on the mains feed into the house. I guess the benefit is when you have a dodgy toaster it only trips that circuit instead of your whole house though.

Not only would it be inconvenient if your entire house tripped on a GF, but it would also make finding the source nearly impossible. GFCI protection at the outlet is not only convenient but practical in most cases. People are rarely electrocuted on the concealed wiring system. Having the receptacle trip that you are currently plugged into immediately informs you which device is faulty. Arc Fault protection, OTOH, probably makes more sense on the circuit breakers but they are more for preventing fire.

They only have to be up to code when they were built. Any later Including aslteration are also inspected. You would think there would be a little buy-in by the owner for especially if he wants to bring bands in there. They could run an entirely separate circuit if they really wanted to - out of a breakout panel all within code.

Agreed. The cost of remedying the electrical system at the club is nothing compared to a wrongful death lawsuit.

My NEC knowledge is probably out of date considering I took my electrical license using the 2005 NEC. However, I performed arc flash studies and provided electrical safety training for industrial maintenance staff from 2013-2018. I wouldn't call myself an expert. Just someone who knows more than the average lay person regarding electrical safety.

 

[crazyBassClown]

Not only would it be inconvenient if your entire house tripped on a GF, but it would also make finding the source nearly impossible. GFCI protection at the outlet is not only convenient but practical in most cases.

We seem to be able to find the source of ground faults ok here in OZ even though all electrical installs for decades have required whole house RCD/GFCI at the box. Protection at the outlet also does nothing for someone who comes into contact with a live light or lightfitting, a much higher possibility these days with LED lights with heatsinks.

 

[Old Garage-Bander]

We had a singer in the band a number of years ago who just wouldn't pay attention. We played the same venue regularly, and every time he would complain about getting a shock from the mic. And every time it happened I told him not to plug his guitar amp into the outlet on the other side of the stage, but into the same power box we were using for the PA. Every time he would grudgingly move his amp plug to the power bar and the problem went away. And the next time we played the same venue he did the same thing. I tried explaining that there was a different ground level on the circuit he was plugging into, but I guess he didn't understand. Maybe he got shocked once too often and it addled his brain.

Once again, Einstein was right.