Venue outlets have open ground. What does that mean?

[Boundary Effect]

The open-ground circumstance can also occur if the guitar player has a vintage tube amp with an original 2 prong power cord. The chassis of the amp is not grounded (open circuit) and may have a different potential (voltage) compared to the electrical ground. The electric guitar (or bass) player's hands are on the strings of his instrument which are connected to the amp chassis. When this performer's lips touch the metal of the microphone connected to a properly grounded sound system, current will flow. I recall seeing this as an audience member once at a very large, all weekend festival with pro staging. Needless to say, the artist was pissed.

That ground fault tester is a must for everyone's bag. I always plug mine in at new venues. Heavy duty power strips that use receptacles like those found in household receptacles are preferred. I do not like switches or fuses on mine. Avoid cheap. If the power source for the band comes from one location, plug your heaviest duty power strip into that and then distribute the power from that in a "star" fashion. In other words, avoid daisy chaining a string power strips.

 

[Smallmouth_Bass]

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.

If it was that old, why would they have three prong outlets?

I am not even sure the business operating there owns the building. That would make things more of a hassle to get fixed.

Which brings up another question (maybe I should start a new thread): how many of you test the electrical outlets when playing a stage or venue? I bought the outlet tester a long time ago - probably in relation to something I read here on TalkBass - and forgot I even had it!

 

[higain617]

If it was that old, why would they have three prong outlets?

I am not even sure the business operating there owns the building. That would make things more of a hassle to get fixed.

Which brings up another question (maybe I should start a new thread): how many of you test the electrical outlets when playing a stage or venue? I bought the outlet tester a long time ago - probably in relation to something I read here on TalkBass - and forgot I even had it!

When renovating old buildings, they will update the outlets, panel, etc. with the existing wiring. It's too difficult and expensive to replace, especially if the walls are plaster.

 

[Old Garage-Bander]

AFAIK, a GFCI does not need a ground connection to work with. My understanding is that they work by measuring the difference between the current flowing in the hot leg and the current returning in the neutral. They should be very, very nearly the same. Any difference indicates that current is finding an alternate return path, which could be through you. They trip at a difference that is less than what has a significant chance of harming you.

With that said, the venue really needs to fix this ASAP. I agree with having a serious talk with them, reminding them of their potential liability if someone is harmed due to their violation of electrical safety codes. It would be a courtesy to your fellow musicians in other bands that play there if you tell them about the hazard as well. Calling in the inspectors is very much a last resort - do you really want to see the venue where you play shut down?

Correct on the GFIC comment. My understanding is that some local electrical codes specify using a GFCI outlet where a ground is not available in the outlet box. It's not ideal, but provides more protection than a standard grounding style outlet with no ground connected.

 

[Old Garage-Bander]

I gotta look into this GFCI thing--something like this?: https://www.amazon.com/Grounded-Wat...keywords=portable+gfci&qid=1661358354&sr=8-10

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?

Surge/RFI/EMI have nothing to do with safety protection provided by a proper ground. That being said, without having a ground, you get little or no protection from surges, RFI or EMI.

 

[Smallmouth_Bass]

Surge/RFI/EMI have nothing to do with safety protection provided by a proper ground. That being said, without having a ground, you get little or no protection from surges, RFI or EMI.

So, would a GFCI outlet provide that protection?

 

[Old Garage-Bander]

No such thing a a "minor wiring fault" on a wall outlet, unless you consider your personal safety to be a minor concern.
Most devices that filter against power line noise or surges, don't fix safety problems that exist at the outlet they are plugged into.

 

[Smallmouth_Bass]

So, I did post a separate thread and poll in conjunction with this subject for those of you interested:
Do you test the electrical outlets before plugging in?

 

[Keyser Soze]

Next time you play there use a portable GFCI on every thing you plug in .... I use one whenever I plug in anything out doors and on the job as an electrician....

You're an electrician and your name is Tommy Sparks?!!

Never saw that one coming. LOL! Born to be electric!

 

[Old Garage-Bander]

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.

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.

 

[John Cribbin]

Unless you play Death Metal, don't plug and play there until it's made safe.

 

[Old Garage-Bander]

I can imagine a situation where that would be true, but it's not a very likely situation - the likely scenarios are different pieces of gear at different voltages (I have experienced this) and a rubber mat does nothing for those situations. The situation where I can imagine it being true are when your equipment has a fault, you're wired to high voltage, and you're breaking the return path to ground with the rubber mat. The real fix there is not a rubber mat (there are a lot of things you can touch and get zapped when standing on the mat), it's fixing the fault in your gear.

The fact that you have hum and the fact that the 3rd wire is not grounded are independent things - they may or may not have anything to do with each other.

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.

 

[Wasnex]

I'm also not an electrician, but I have had a guitarist friend thrown back against the wall when he stepped up to a mic where the power wasn't grounded. It was a dive where there was an outlet that wasn't grounded and one that was, and people that knew the place knew not to use the ungrounded one.

I believe - and more knowledgeable people can confirm or correct me here - that bringing a rubber mat to stand on when you play can help as a safety precaution.

The current path is usually not between the mic and the floor, so rubber mat probably won't help in most situations. An exception would be if you are barefoot standing on cement or the ground. In this case the cement is ground potential.

AFAIK the problem is usually between the chassis of an amp and the chassis of the mixer. The chassis of both should be grounded, so there is no difference in potential between them. The reality is that if there is any current flowing through the ground, that it will produce a small voltage drop. So it's possible to still get a little tingle on your lips.

 

[Old Garage-Bander]

So, would a GFCI outlet provide that protection?

Like I said earlier. It's not the ideal situation, but because a GFCI outlet works on different principle than the ground from an outlet, it will provide additional protection.
Even with proper grounds in place, they rely on the circuit breaker to trip. You could have a high current situation, high enough to kill, and still not trip the breaker.
GFCI's act on a very small current imbalance between hot and neutral. They also act much faster than a breaker.
Ever wonder why you normally only see GFCI's in wet locations; bathrooms, kitchens, garages, swimming pools/ hot tubes? It's more likely those places will present a danger not as likely elsewhere.
The best world will be properly grounded and have GFCI protection.

I think the term GROUND in GFCI, is an unfortunate choice that only leads to confusion.

 

[micguy]

A grounded device is one way to try to make it safe. Unfortunately, it's not a guarantee of safety. There are two general ways of protecting people - one is to ground absolutely everything, so everything is at the same potential. The other is double insulation, which means that every device avoids conducting electrify outside the device - it's constructed with methods that help make sure that faults are extremely unlikely.

Double insulated stuff is (if everything is double insulated) actually more fault tolerant than grounding everything. One faulty device, if everything is double insulated, means you have one "hot" device. To hurt someone, though, you need to complete a circuit, which means you either need a second faulty device, if everything is designed for double insulation. With everything grounded, you only need one faulty device - every other device will provide a ground path, which completes a circuit. If there is a "hot" device on a stage, grounds on the other devices actually make the situation more dangerous - they complete the circuit path.

Anyway, a lot of old buildings where clubs are located were constructed in an era where there was no 3rd wire ground on outlets - the wires aren't there in the wall to hook a ground to. But, a lot of musicians come in, and their gear has 3 prong plugs. So folks will put in 3 prong outlets, to make things easy. Is that unsafe? Maybe - it depends on a lot of factors.

The piece of gear you should carry is not an outlet tester - yes, that tells you something (and can send you into discussions about the National Electrical Code), but it's not the direct way to figure out if you're safe or not. What you need to know is if there are voltage differences between your gear and the other stuff on stage. A cheap AC voltmeter is what you need - you measure between the strings on your bass and the microphone you're about to sing into, the strings of everyone else on stage, etc. If you see voltage there, you are in danger - it could be the place's wiring, it could be a fault in your gear (which the outlet tester won't find), and you'll get something from a tingle to a shock that will snap your head back (Yes, I have experienced this).

 

[Dirk Diggler]

FYI the noise is the symptom of an open ground, not the cause.

Look for a properly working outlet at the venue and use that until they fix it.

For years a guitar player I played with used to run his own amp ground outside the club to a spike in the ground.
Solved so many noisy strat problems.

What Is An Open Ground? - Waypoint Inspection Property Inspection

It is risky to run with an open ground, not a risk I'd be willing to take.

 

[TomB]

A grounded device is one way to try to make it safe. Unfortunately, it's not a guarantee of safety. There are two general ways of protecting people - one is to ground absolutely everything, so everything is at the same potential. The other is double insulation, which means that every device avoids conducting electrify outside the device - it's constructed with methods that help make sure that faults are extremely unlikely.

Double insulated stuff is (if everything is double insulated) actually more fault tolerant than grounding everything. One faulty device, if everything is double insulated, means you have one "hot" device. To hurt someone, though, you need to complete a circuit, which means you either need a second faulty device, if everything is designed for double insulation. With everything grounded, you only need one faulty device - every other device will provide a ground path, which completes a circuit. If there is a "hot" device on a stage, grounds on the other devices actually make the situation more dangerous - they complete the circuit path.

Anyway, a lot of old buildings where clubs are located were constructed in an era where there was no 3rd wire ground on outlets - the wires aren't there in the wall to hook a ground to. But, a lot of musicians come in, and their gear has 3 prong plugs. So folks will put in 3 prong outlets, to make things easy. Is that unsafe? Maybe - it depends on a lot of factors.

The piece of gear you should carry is not an outlet tester - yes, that tells you something (and can send you into discussions about the National Electrical Code), but it's not the direct way to figure out if you're safe or not. What you need to know is if there are voltage differences between your gear and the other stuff on stage. A cheap AC voltmeter is what you need - you measure between the strings on your bass and the microphone you're about to sing into, the strings of everyone else on stage, etc. If you see voltage there, you are in danger - it could be the place's wiring, it could be a fault in your gear (which the outlet tester won't find), and you'll get something from a tingle to a shock that will snap your head back (Yes, I have experienced this).

Two things (from a non-electrician): installing a 3-prong outlet in an ungrounded box may or may not be safe (the open ground thing), but I can’t imagine it’s legal anywhere that inspections occur.

Also, I recall one of these threads mentioning that older clubs can end up with multiple ground paths (not proper but it happens) and that any differential between them (which could happen on a stage served by multiple circuits) is an additional hazard. Am I recalling that correctly?

 

[Wasnex]

Quite frankly folks. I’m appalled at the number of responses that want to call in a governmental agency. What? Why? Is there an issue with the electrical system…unequivocally YES. Is it the venue owner’s responsibility to get it corrected? YES Should you refuse to play until corrected? YES. Should you summon the government? NO!!!

Please add me to your list.

If the OP does not take the job, someone else will. So eventually someone is likely to get hurt because of the venue's unethical behavior. The owner has no right to put employees and temp workers at risk, and "the man" should have been called long ago.

This is a long-term problem, and the venue is obviously not going to fix it unless they are forced to do the right thing. They currently have a choice, fix the problem or face the eventual consequences. If they get shut down, fined, or sued for killing someone, it's on them. Or maybe the owner will get electrocuted due to the fault, and win the Darwin award.

 

[micguy]

Two things (from a non-electrician): installing a 3-prong outlet in an ungrounded box may or may not be safe (the open ground thing), but I can’t imagine it’s legal anywhere. Also, I recall one of these threads mentioning that older clubs can end up with multiple ground paths, and that any differential between them (which could happen on a stage with multiple circuits) is an additional hazard. Am I recalling that correctly?

It probably isn't "legal" in the sense that, if an electrical inspector comes and checks everything, you'd fail the inspection. However, if the electrical police started going into every building and house in the country and hauled folks to prison if their houses have 3 prong outlets that aren't grounded, there aren't anywhere near enough jails in the country to hold all those people - it's more widespread than you think.

If the outlets aren't grounded, but you hook the PA and the amps into the same outlet (on a power strip or something), everything will be at the same voltage, so you're relatively safe in that case, but you may very well blow fuses or breakers.

If you're in different outlets, then you aren't grounded together, and indeed, if a stray hot wire comes into contact with the ground terminal, now you're in real danger - since the safety ground isn't grounded, there won't be current will to blow a fuse or breaker - the amount of current that you pass if you end up wired between hot and ground also won't - thus the development of the GFCI.

 

[Smallmouth_Bass]

FYI the noise is the symptom of an open ground, not the cause.

Look for a properly working outlet at the venue and use that until they fix it.

For years a guitar player I played with used to run his own amp ground outside the club to a spike in the ground.
Solved so many noisy strat problems.

What Is An Open Ground? - Waypoint Inspection Property Inspection

It is risky to run with an open ground, not a risk I'd be willing to take.

You know, looking at the pictures in the link above and the coded lights, I am not so sure there was an open ground after all. I am fairly certain I had two orange lights. I checked my outlet tester on my house outlet and got the same thing which indicates it is correct. Either my memory is failing me or I read it incorrectly that evening. My eyes are not what they used to be. Throw in some dim lighting and... I'll have to check again next time we're there.

So, would dimmers (lighting) on a circuit cause equipment hum?