Tube amplifiers and the real risks of using them in ungrounded outlets.

[GustHFS]

Since I joined this forum I've been looking for specific information about the real risks and possibilities of damage when connecting a tube amplifier (in my case a DSL20HR) into an ungrounded outlet. Let me explain: In the country where I live, although there are national regulations and everything else, it is not very common to find sockets with proper grounding so many here always use their tube amplifiers without grounding while others not always, or only when available. Obviously this is perfectly possible, and I myself have grounded outlets in my house. The problem is when we need to take the amplifier to a rehearsal place or even a gig, the chance of being lucky enough to find a grounded outlet is almost zero. In addition to grounding problems, here we also have nearby cities with different voltages (127 and 220 volts) which makes everything more complicated if we are not careful. Therefore, I would like to know about the real risks of using a tube amplifier in this condition, if there is, in addition to the obvious risks such as electrical discharges, any real risk of severe damage to the equipment under normal usage conditions, and if there is anything that could be done to minimize these risks in situations where grounding is not available. Thank you guys in advance for any tips or opinions.

Gust

 

[Pete Farrington]

Ungrounded valve amps are no more hazardous than ungrounded solid state amps, or any other items of mains electrical equipment that has a metal chassis etc accessible to the user.
The best you can do to mitigate the risk is use a wireless link, rather than an instrument cable, between your guitar and whatever comes next (eg tuner pedal, wah etc). And wear rubber soled shoes when touch, adjusting your amp.

My understanding is that the dual voltage systems are a particularly issue in South America. I don’t know enough about how things are there to suggest any useful mitigation for that.

 

[GustHFS]

Ungrounded valve amps are no more hazardous than ungrounded solid state amps, or any other items of mains electrical equipment that has a metal chassis etc accessible to the user.
The best you can do to mitigate the risk is use a wireless link, rather than an instrument cable, between your guitar and whatever comes next (eg tuner pedal, wah etc). And wear rubber soled shoes when touch, adjusting your amp.

My understanding is that the dual voltage systems are a particularly issue in South America. I don’t know enough about how things are there to suggest any useful mitigation for that.

Thanks for the reply, Pete! In fact, the dual voltage system here is something very complicated to us and the only way to deal with this is to pay close attention, and keep always handy at least one of those voltage tester pens/screwdrivers.
As for grounding, I really thought about using a wireless system, it might be an option. The risk of electrical discharge in the user seems obvious to me, and all the precautions you suggested I also consider extremely important, but what I would really like to know is whether, even if there were no problems with discharges or voltage leaks, even so would still be a risk of damage to the amplifier and the other devices in the chain, such as pedals, etc. due to use in those sockets without grounding.
That notice on the rear panel with the words "This apparatus must be earthed" is what is a little scary, as it seems to warn of the imminence of a tragedy when we use our two-pin plugs without grounding, lol

Gust

 

[Gene Ballzz]

Well, without proper grounding, one real danger of equipment damage comes when a device gets connected to another ungrounded piece of gear that is on a different circuit, that may also be on a different "phase" of the AC, as well as possibly having the neutral and hot leads backwards/crossed!
Just Sparkin'
Gene

 

[paul-e-mann]

I grew up in a really old house that didnt have grounded outlets, I used a 3 prong to 2 prong converter to plug my amp in the wall my entire youth and never died from it.

 

[GustHFS]

I grew up in a really old house that didnt have grounded outlets, I used a 3 prong to 2 prong converter to plug my amp in the wall my entire youth and never died from it.

That's exactly what happens here, Paul! These are the secret weapons most people use around here, LOL




Gust

 

[william vogel]

That adapter is great as long as the receptacle is grounded, otherwise it’s just a false sense of security. As long as you are in an environment where nothing is earthed you’ll be floating amongst the potential of the device. If you yourself are actually earthed, you really are taking a risk of being shocked or electrocuted because the guitar strings are shielded to the chassis.

 

[GustHFS]

Well, without proper grounding, one real danger of equipment damage comes when a device gets connected to another ungrounded piece of gear that is on a different circuit, that may also be on a different "phase" of the AC, as well as possibly having the neutral and hot leads backwards/crossed!
Just Sparkin'
Gene

Thanks Gene! I'll try to read your explanation more carefully, because at first it seemed a little confusing to understand. It's not your fault, English is not my native language so I often need to translate the text first and try to find a meaning it better be intelligible to me.

Gust

 

[GustHFS]

That adapter is great as long as the receptacle is grounded, otherwise it’s just a false sense of security. As long as you are in an environment where nothing is earthed you’ll be floating amongst the potential of the device. If you yourself are actually earthed, you really are taking a risk of being shocked or electrocuted because the guitar strings are shielded to the chassis.

Got it, William. So, in this case, wearing shoes with rubber soles as suggested by Pete would be a palliative option to be able to protect yourself, even if only partially.

Gust

 

[AtomicRob]

If you can get a GFCI extension cord or pigtail, this will provide protection from shock even on ungrounded outlets. A GFCI will trip if there is more than a few milliamps difference between the current on the hot and neutral wires.

 

[Pete Farrington]

get a GFCI

Great idea!
They’re referred to as an RCD in the UK.
Anything using mains power with metalwork that someone can touch should be powered via one of these. You may need a few.
Sod’s law shows that the things not fed via a GFCI are the most likely to fail dangerously.

They’re possibly most beneficial on the PA, as it may not be feasible to use wireless types for all mics.
Slipping a foam wind / pop filter cover over any and all wired mics would also be a good idea.

one real danger of equipment damage comes when a device gets connected to another ungrounded piece of gear that is on a different circuit, that may also be on a different "phase" of the AC, as well as possibly having the neutral and hot leads backwards/crossed!

I’m stuck trying to see how that might be a problem

I grew up in a really old house that didnt have grounded outlets, I used a 3 prong to 2 prong converter to plug my amp in the wall my entire youth and never died from it.

These are the secret weapons most people use around here

Yes, having nothing grounded is a bit safer than having some outlets grounded but some not.
The hazard when nothing electrical is grounded comes from stuff that’s conductive and is grounded by default, eg a damp basement floor, water / heating pipes.

J M Fahey is a music equipment manufacturer in Buenoes Aires,Argentina, he’s extremely knowledgeable and helpful, occasionally active on various forums eg the gearpage, solidstateguitar. He’s mentioned these grounding and dual voltage issues, he may be able to off some insight / advice.

 

[GustHFS]

I thank you all guys for the great help and cool tips!

Yes, I have used sometimes what you call a GFCI/RCD extension cord in situations where ground is not available. I didn't comment on it initially because I thought it was a palliative and unsafe solution and that it was only used around here. But in the end I learned that it is common even for you to use 3 to 2 pin converters. There are several good manufacturers of these extension cords around here, I use a Clamper brand device that has micro breakers and protection fuse. It's what I should keep using until there's a better solution to this problem.

Gust

 

[ELS]

I want to point out that all switch mode power supplies have the so called "death cap"
there's just 1 for a power supply that doesn't have a ground lead, and 2 for one that does.
For the ones that don't have ground leads, the death cap can be connected to the output ground with a 50/50 chance (which way you plug it in)
for the ones with a ground, no matter in what polarity you plug it in, it will have the 2 death caps connected, which will form a voltage divider and basically be a death cap from 1/2 line voltage, to the ground.
PC's use a switch mode power supply with 2 of those caps for example.

It could be that an RCD/GFCI trips even in a non-fault scenario in this case, if there's many musicians, and many power supplies (for a pedal board or a PC for recording/whatever).
There could easily be more than 15mA of total current flow from line to earth.
So maybe use multiple RCD's/GFCI's then for each rig.

This isn't to say that it's an excuse for not grounding stuff, it's very comfortable when everything is grounded.
When it's not, SMPS's like I mentioned, and just leakage currents will always give you a mild zap when you are coming into contact with a ground.
The mouth, the back of your fingers, and any wet flesh part of your body is the most sensitive of this.
I've even had cases where I think I don't have a good ground, but I actually do, in cases where your body just absorbs enough AC from the mains lines going around you that you can feel a zap when you touch a ground with the back of your hand.
Now come to think of it, I should mention, Don't test for ground with your tongue! rather use the back of your hand.

 

[GustHFS]

Apparently, we are now starting to have some good references, ideas and tips on the subject, something that had not been specifically addressed in this forum (and in others as well, because I have already done research about it and found very little information, almost nothing to say the true). So I think the objective is beeing achieved here.

Gust

 

[ELS]

Apparently, we are now starting to have some good references, ideas and tips on the subject, something that had not been specifically addressed in this forum (and in others as well, because I have already done research about it and found very little information, almost nothing to say the true). So I think the objective is beeing achieved here.

Gust

I hate when talk about this is just silenced on most other forums...
Yes indeed ungrounded equipment is dangerous, but being ignorant of it is even more so!

 

[Crikey]

That adapter is great as long as the receptacle is grounded, otherwise it’s just a false sense of security. As long as you are in an environment where nothing is earthed you’ll be floating amongst the potential of the device. If you yourself are actually earthed, you really are taking a risk of being shocked or electrocuted because the guitar strings are shielded to the chassis.

Wireless

 

[paul-e-mann]

That's exactly what happens here, Paul! These are the secret weapons most people use around here, LOL


View attachment 128344

Gust

Thats it! Except mine were gray or orange.

 

[RLW59]

When I was young in the USA, 3-prong grounded outlets had just recently become mandatory in new buildings. Lots of houses and clubs still had legacy 2-prong non-polarized outlets. Most used amps had 2-prong nonpolarized plugs.

Shocks and tingles taught us that electricity only hurts if it flows through you -- from a supply to a return. You can grab a hot wire carrying 110~240V and won't feel a thing,  unless some other part of your body touches a ground or neutral.

We learned to never stand barefoot on dirt or a concrete slab floor (damp leather soles can conduct a bit, so if you had to stand on a conductive surface, rubber soled sneakers were safer).

But most important, we learned to never touch any metal part of our guitars and amps while touching metal microphones, other musicians, their instruments and their amps, PA's, lighting equipment.

Never let your body become a pathway to ground and you'll never get shocked. That habit is still ingrained in me all these decades later.
‐---------------------------
A big part of why a grounded plug is safer is because it's polarized. So as long as the outlets are wired correctly, every amplifier and other electrically devices are all the same polarity. So power won't flow through you from one chassis to another chassis.

The ground wire mostly protects from catastrophic failures. Those are pretty rare (arguably, the ground wire is more about reducing the risk of fires than preventing shocks).

But back when amps had non-polarized 2-prongs, any time you had 2 amps running there was a chance of electrocution if you touched both amps at the same time (or guitars connected to them).

 

[Gene Ballzz]

When I was young in the USA, 3-prong grounded outlets had just recently become mandatory in new buildings. Lots of houses and clubs still had legacy 2-prong non-polarized outlets. Most used amps had 2-prong nonpolarized plugs.

Shocks and tingles taught us that electricity only hurts if it flows through you -- from a supply to a return. You can grab a hot wire carrying 110~240V and won't feel a thing,  unless some other part of your body touches a ground or neutral.

We learned to never stand barefoot on dirt or a concrete slab floor (damp leather soles can conduct a bit, so if you had to stand on a conductive surface, rubber soled sneakers were safer).

But most important, we learned to never touch any metal part of our guitars and amps while touching metal microphones, other musicians, their instruments and their amps, PA's, lighting equipment.

Never let your body become a pathway to ground and you'll never get shocked. That habit is still ingrained in me all these decades later.
‐---------------------------
A big part of why a grounded plug is safer is because it's polarized. So as long as the outlets are wired correctly, every amplifier and other electrically devices are all the same polarity. So power won't flow through you from one chassis to another chassis.

The ground wire mostly protects from catastrophic failures. Those are pretty rare (arguably, the ground wire is more about reducing the risk of fires than preventing shocks).

But back when amps had non-polarized 2-prongs, any time you had 2 amps running there was a chance of electrocution if you touched both amps at the same time (or guitars connected to them).

^^^^^^^ Wise and insightful observations and words, right there! ^^^^^^^

I learned the same lessons at apparently a similar time period! That knowledge propelled me to develop noise and shock free AC distribution and grounding schemes for often very large sound/PA systems, all the way up to concert level rigs! Lots of details, including that even good commercial/industrial power layouts don't always factor in the nuances of noise and hum free audio and video interconnection!

Not Shockin'
Gene

 

[BlueX]

A big part of why a grounded plug is safer is because it's polarized. So as long as the outlets are wired correctly, every amplifier and other electrically devices are all the same polarity.

Well written, but I must comment on this. In big parts of Europe, and maybe elsewhere, also plug and socket with protective earth are non-oriented. You can turn the plug 180 degrees and it will still fit.