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Small electric shocks from guitar strings

Postby Bill S » Wed Apr 26, 2017 9:53 pm

I have a small studio and have recently moved it from the UK to Spain. I have been using it in Spain for the last month or so with no problem. Today, when I plug in any of my three electric guitars into my Focusrite 6i6 interface I am getting a small, but noticeable and unpleasant electric shock when I first touch the strings or any other metal part of any of the guitars. I have had the three guitars for years, the Focusrite for ages too, I have not introduced anything new electrical into the house today.

Can anyone suggest what could be causing this please?
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Re: Small electric shocks from guitar strings

Postby Jumpeyspyder » Wed Apr 26, 2017 10:26 pm

I'm guessing signal chain is:-

Guitar >Focusrite> PC / Mac / laptop ?
(if its a laptop are you using mains power ?)

Is there any other gear in the chain?

First thought (assuming everything is working correctly) would be is there an earth in the system or is the earth 'floating' ?

If there is a mains plug involved check both the plug and socket have a good earth connection.
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Re: Small electric shocks from guitar strings

Postby Wonks » Wed Apr 26, 2017 10:45 pm

It's not that you're wearing different clothes or different shoes that are generating static and discharging when you touch the grounded strings?
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Re: Small electric shocks from guitar strings

Postby Hugh Robjohns » Wed Apr 26, 2017 11:02 pm

There are two kinds of electric shocks, and two possible problem scenarios, and you need to figure out which applies to your situation as they are solved in different ways.

The first kind of shock is due to static electricity -- something gets charged up to hold a high static voltage, and that then gets discharged when in contact with something grounded. It causes an instantaneous shock, which can be quite painful, but only for the briefest moment but is nt normally dangerous to the person (although it can damage the equipment in some circumstances).

The second kind of shock is due to an AC voltage across the body, normally from the mains, and it usually creates a continuous throbbing which can be fatal...

The two classic situations are first, where the person is charged up (physical movement combined with some clothing materials can create a substantial static charge) and touches something that is grounded, discharging the static; while the second is where the equipment is not grounded and a voltage develops which then passes to ground through a person. Thats the lethal one!

Difficult to know which combination applies to you from here, but if the interface is grounded via the mains earth a likely explanation is that you are acquiring static charge through your clothes in the dry Spanish atmosphere.

Perhaps more likely, the interface is not properly earthed and so it's nominal ground is 'floating up to half mains voltage because of its power supply design. You are then providing a path to earth and sensing the shock.

A lot of equipment is 'double insulated' which means it doesn't have a solid connection to the mains safety earth, and it is very easy to construct a complete laptop-based music system with no hard ground connection, resulting in the kind of shock you describe.

If that is the case, then arranging for the interface to be properly grounded should solve the problem. Check out the Groundology plug, which offers one possible solution.

http://www.soundonsound.com/reviews/gro ... ction-plug
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Re: Small electric shocks from guitar strings

Postby Guest271017 » Wed Apr 26, 2017 11:10 pm

Hugh Robjohns wrote:Perhaps more likely, the interface is not properly earthed and so it's nominal ground is 'floating up to half mains voltage because of its power supply design. You are then providing a path to earth and sensing the shock.

This. Don't touch any metal on the guitars and put your lips to a metal screened mic, you won't taste right for a while.
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Re: Small electric shocks from guitar strings

Postby Guest271017 » Wed Apr 26, 2017 11:16 pm

Before I use any mic, I wet my finger and while touching the strings, touch the mic to see if the grounds aren't FUBAR. Here in the states, we have three pronged grounded outlets. You should see the creative ways I've seen them wired.
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Re: Small electric shocks from guitar strings

Postby resistorman » Thu Apr 27, 2017 3:46 am

mashedmitten wrote:Before I use any mic, I wet my finger and while touching the strings, touch the mic to see if the grounds aren't FUBAR. Here in the states, we have three pronged grounded outlets. You should see the creative ways I've seen them wired.

Yoiks! You might consider touching the guitar strings to the mic without putting your body and possibly your heart in the circuit! If there's any ground funny business you will see the spark and certainly hear it if the equipment is live.
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Re: Small electric shocks from guitar strings

Postby Bill S » Thu Apr 27, 2017 8:32 am

Thanks very much for your replies. Other evidence - my wife's hairdryer's plug gets noticeably hot after 5 minutes use. It's a new device top quality brand, bought in Spain. I don't understand electrics and I am thinking I need to try to find good English speaking electrician as a matter of priority.
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Re: Small electric shocks from guitar strings

Postby Guest271017 » Thu Apr 27, 2017 9:20 am

Bill S wrote:Thanks very much for your replies. Other evidence - my wife's hairdryer's plug gets noticeably hot after 5 minutes use. It's a new device top quality brand, bought in Spain. I don't understand electrics and I am thinking I need to try to find good English speaking electrician as a matter of priority.

Not familiar with Spanish mains, but here we can buy a $5 tester that tells if the wiring in the wall's correct.

Spanish mains, never thought I'd use that in this context. :lol:
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Re: Small electric shocks from guitar strings

Postby Hugh Robjohns » Thu Apr 27, 2017 10:06 am

Bill S wrote:Other evidence - my wife's hairdryer's plug gets noticeably hot after 5 minutes use.

So does her hair, I expect... not particularly relevant to your potential grounding issues. Any plug will get hot after several minutes carrying high currents... although it does suggest that the plug/socket terminals have higher resistance than they should have, almost certainly because they have become tarnished, or it's a poor quality wall socket.

I don't understand electrics and I am thinking I need to try to find good English speaking electrician as a matter of priority.

Always a good idea...

We can probably solve your music gear problem if you can give us more detail about what is connected to what and how, and what the various power connections are.

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Re: Small electric shocks from guitar strings

Postby Bill S » Thu Apr 27, 2017 3:13 pm

Electrician came round and changed the UK plug on my four way UK adapter to a Spanish one - he thought that was the weak link in the chain - and, touch wood, it seems sorted. I will feel more confident about that if it behaves for a month or two.

As Hugh asked, I have a simple set up:

HP all in one PC
Focusrite 6i6
iLoud Micro Monitors
Second and slightly ancient monitor - the connection to the HP isn't great - VGA to HDMI.
Roland A300 Pro keyboard

That's it - no outboard gear.

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Re: Small electric shocks from guitar strings

Postby Guest271017 » Thu Apr 27, 2017 3:34 pm

Bill S wrote:Electrician came round and changed the UK plug on my four way UK adapter to a Spanish one - he thought that was the weak link in the chain - and, touch wood, it seems sorted. I will feel more confident about that if it behaves for a month or two.

As Hugh asked, I have a simple set up:

HP all in one PC
Focusrite 6i6
iLoud Micro Monitors
Second and slightly ancient monitor - the connection to the HP isn't great - VGA to HDMI.
Roland A300 Pro keyboard

That's it - no outboard gear.

Bill

Glad it's sorted, electric shocks can make you gun shy. It will take a while for that apprehension to wear off. :thumbup:
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Re: Small electric shocks from guitar strings

Postby Hugh Robjohns » Thu Apr 27, 2017 3:41 pm

Bill S wrote:Electrician came round and changed the UK plug on my four way UK adapter to a Spanish one - he thought that was the weak link in the chain - and, touch wood, it seems sorted.

If you had a UK 13A plug on your four-way adapter, I guess you were plugged into the wall outlet via a travel adapter. If so, it's quite likely that there was no safety earth connection through the adapter and hence the shocks.

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Re: Small electric shocks from guitar strings

Postby Martin Walker » Thu Apr 27, 2017 3:56 pm

Wonks wrote:It's not that you're wearing different clothes or different shoes that are generating static and discharging when you touch the grounded strings?

Many years ago I used to be able to reliably crash my Commodore 64 computer after walking across the carpet in my new (and mostly nylon) socks and then sitting down to touch its keyboard.

Ever since I've always made sure that the majority of the building materials in my socks are man-made fibres :beamup:


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Re: Small electric shocks from guitar strings

Postby Guest271017 » Thu Apr 27, 2017 4:09 pm

Lack of humidity increases static buildup, also.

Wife has these fuzzy slippers and the habit of dragging her feet across the carpet. First couple of times I got shocked on the lips I told her to ground herself before smooching. She didn't take the hint, so every time she'd lean down to kiss me, I tell her to stop and touch my finger to her lips to ground her. I'd move in slow so the spark would jump the farthest and give the most snap. She touches the metal screw of an outlet face plate without fail, now.
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Re: Small electric shocks from guitar strings

Postby Martin Walker » Fri Apr 28, 2017 4:35 pm

mashedmitten wrote:Wife has these fuzzy slippers and the habit of dragging her feet across the carpet. First couple of times I got shocked on the lips I told her to ground herself before smooching.

Ouch! :o


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Re: Small electric shocks from guitar strings

Postby Hugh Robjohns » Fri Apr 28, 2017 4:57 pm

It could have been a lot worse! :oops:
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Re: Small electric shocks from guitar strings

Postby Guest271017 » Fri Apr 28, 2017 5:30 pm

Hugh Robjohns wrote:It could have been a lot worse! :oops:

I don't know, might increase pleasure. :shock: :mrgreen:
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Re: Small electric shocks from guitar strings

Postby Martin Walker » Sun Apr 30, 2017 8:45 pm

mashedmitten wrote:
Hugh Robjohns wrote:It could have been a lot worse! :oops:

I don't know, might increase pleasure. :shock: :mrgreen:

Put away those bulldog clips RIGHT NOW mashedmitten! :beamup: :bouncy:


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