Well, yeah, again, electric shocks from mics !!

[Folderol]

Personally, I've never seen and Earth-Neutral swap in any domestic or industrial situations, but plenty of Line-Neutral ones, which are potentially far more dangerous - including in a new build that a friend moved into (he asked me to check the wiring generally).
Just my 2d {old money}

[Wonks]

Yes. Earth cables are pretty distinctive and unless it's a seriously incompetent DIY installation (or anything by the sparks who wired up Zukan's extension a few years ago), any cable swaps are likely to be line/neutral than neutral/earth.

[pk.roberts]

If I have a ... RCD and I'm using it in a situation where there's an earth / neutral swap then it's going to trip. I won't know what the problem is, but I will know there is a problem of some description. Reasonable?

Yes. RCDs trip if the current flowing in the Line side differs from the current flowing in the Neutral side by 30mA (or more). The assumption is that the missing current is erroneously flowing to earth somewhere due to a fault, and potentially via a person, and so the power is tripped off.

So if neutral and Earth were swapped in the wiring somewhere (highly unlikely though that is), the current would flow between the Line and Earth connections. There would be an imbalance between the L and N paths in the RCD, and it would therefore trip out.

Just a slight correction; a 30mA RCD must not trip at up to half it's rating (i.e. 15mA of current imbalance), but must trip by it's full rating. In other words, a 30mA RCD should trip with a L-N current imbalance in the range 15 to 30 mA.
As an aside, that's why, given the amount of 'slightly leaky' switch mode power supplies we use these days, protecting a whole supply with a single 30mA RCD is not always a good idea.

[mushy55]

I just set up an unused room in my business unit for my band to rehearse in. Got an electrician to install 4 sockets(one on each wall). I had the mixer and speakers plugged into one side and a guitar amp(brand new)into the adjacent socket. Started getting little zips from the mic. when playing guitar too. Tried isolating the speakers, mixer, changing leads etc but was still happening. Plugged the PA/mixer into a different socket(not the guitar amp socket, the one to the left of and problem solved. Would this point to the fault being socket related? I’ve just ordered a socket tester and PAT tester but they won’t be arriving for a few days and it’s bursting my brain .

[MOF]

Is it static electricity (wearing trainers or plastic soled shoes in a dry atmosphere with nylon carpets or tiles)? I don’t think you would get little zaps from faulty wiring.

[mushy55]

Possibly but it doesn’t do it when I run it from different sockets?

[Folderol]

Hmm, could be a disconnected Earth in the socket so static can build up. There's two ways I've seen that happen:

Terminal not screwed up properly, then wire came out when the socket was being pushed around and screwed in place.

Wire nicked when stripping insulation, then broke while the socket was being fitted.

[Martin Walker]

Wire nicked when stripping insulation, then broke while the socket was being fitted.

Yep, nicked gear does have a nasty habit of going wrong

Martin

[Rene Asologuitar]

Hi everyone !!
Ok, if you are interested(and it is, i'm advising to read through it, plenty of good info) i've posted this discussion before on 24/08/07 ''Electric shock from mic while touching guitar, ......''
I just came across the same problem a while ago, last week !!
My mixer was plugged in to a socket in the wall, so as musicians, but spread in different corners, different sockets (all on the walls).
And, to stop the mic from being electically charged, all i had to do was: Plug out my mixer which was going to a socket in the wall, and in the same socket (on the wall) i plugged in an extention lead, and then i plugged in the mixer in the extention+vocalists guitar ?!
Sounds strange to me but it worked !!
Could anyone explain to me (and to all of us) why did it work ?!
I just can't understand it !! Lost !!
Thanks guys !!

**********************
Great topic, no single right answer. The culprit is proper grounding of individual circuit and equipment.
Rene

[amadjan]

why this gives shock

[Wonks]

why this gives shock

Have you read the start of the thread? It’s generally explained there. Like any long thread, the later posts tend to stray off-topic. So go back to the start and that should explain things.

[Mike Stranks]

OFF TOPIC ALERT!

I took your advice, Wonks...

Where are they now...?? Old compadres that I used to interact with positively on a regular basis...

[ef37a]

OFF TOPIC ALERT!

I took your advice, Wonks...

Where are they now...?? Old compadres that I used to interact with positively on a regular basis...

Not sure who you mean Mike? Many people now seem to use social media* for their information rather than 'formal' forums. I belonged to the online Proton cars owners club forum but closed down and is now just on Twatters or some such.
I shall never use such media.

HR Certainly does not have nearly the turnover of Q's and A's it did a couple of years ago and I fear for its continued existence?

Nice people still at Sound-on-Sound mind and that shows no sign of lack of support.

*Forums are not of course perfect sources of information but at least there is a core of "the Old Guard" to curb the worst excesses. I dread to think what electrical bollox is being told people on SM!

Dave.

[Mike Stranks]

Hi Dave

I was merely reflecting on the fact that some forum stalwarts from the past are no longer here (in the Forums) for whatever reason...

No great philosophical or angst-ridden wail!

[Hugh Robjohns]

People die, retire, change employment or interests, tire of the repetitive nature of forum conversations, or just find more productive things to do with their time. Often people take breaks and later return too — as you have yourself once or twice.

[James Perrett]

People die, retire, change employment or interests, tire of the repetitive nature of forum conversations, or just find more productive things to do with their time. Often people take breaks and later return too — as you have yourself once or twice.

And one or two reappear under different names

[Mike Stranks]

Whoa!

Isn't Social Media fun... sometimes?

When I looked back at the start of the thread, I saw three names (at least) from days gone by, whose opinions I valued...

They're not around any more... that's all... no criticism, moaning, soul-searching, 'Is something wrong here that's made them do that?' on my part... just a bit of reflective nostalgia...

... and relax...

[bedazzled_k]

Hi

So, I've looked through this thread but I'm still not sure what's causing my situation. I'm getting small shocks when my lips touch the mic (I'm a guitar player). This is happening at home but I can test it at the rehearsal space we use next week.

I've got a Labgear socket tester and all of the sockets I'm using are showing as 'CORRECT'.

My setup is as follows:

Schmidt Array pedalboard with TRS patchpanel.
Microphone into TRS socket on patch panel into Boss VE-500. Outputs into patch panel. Output #1 to Gear4Music WPM-200 radio transmitter.
I'm also using the patch panel for guitar in, and guitar out to amp.
The effects (including VE-500) are powered with a Voodoo Lab Pedal Power3 and Pedal Power X 8.
I'm also using a GigRig G3 and its Generator power supply.
The Schmidt Array pedalboard has IEC sockets and the PP3 and Generator are using these. The two power cables are going into an extension lead which is also used by the Gear4Music radio transmitter PSU.

I'm getting the shocks with both an AC-30 and Fender Twin Reverb; both of these amps were recently serviced as well. These are not using the same extension lead as the pedalboard/mic transmitter but are in the same room.

If I use my Audio Technica System-10 wireless guitar rig then I don't get any shocks.

Any thoughts as to what may be causing this issue? As I said, they're not big shocks but I'd obviously rather not have any!

Thanks,

Kevin

[Hugh Robjohns]

I'd lay money on the boss ve500 not being grounded.

[bedazzled_k]

I'd lay money on the boss ve500 not being grounded.

Thanks Rob. It's powered with 9V DC from the Pedal Power 3. Is there a way of ensuring it's grounded?

[Hugh Robjohns]

Yeah... ground it!

Find something that's already grounded, like a guitar amp, and link a wire from there to the mic cable screen.

Just to test the hypothesis, you could ask a friend to hold the plug tip of a guitar lead against the metal barrel of your guitar lead at the patch bay, with the other end touching the metal barrel of the mic lead at the patch bay. That will ground the mic to the guitar amp and will hopefully cure the problem.

As a general rule, 'small shocks' are caused by one of two possibilities.

1. Static from your clothes discharging to a grounded mic

2. Metal parts of ungrounded equipment floating up to half mains voltage and discharging through a grounded person.

The first will happen once and then not on repeated contacts (unless you charge yourself up again by moving s lot or shuffling on the carpet). The second tends to happen on every contact.

[bedazzled_k]

Thanks, that makes sense! I’m not with my gear at the moment but presumably a wire attached to the metal chassis of the Boss and the guitar amp will suffice?

[ef37a]

I suspect the shocks are 'tingles' from unearthed equipment as well.

One solution is a foam gag on the mic but you must, must, MUST get the actual safety of all the kit checked out first before such palliative step.

You will also need to keep the gag dry.

Dave.

[pk.roberts]

The Labgear socket testers are a very simple devices and will NOT necessarily indicate the presence of a good earth connection. To do that you need something like the Martindale EZ165 or a Socket & See SOK34.
In the dim and distant past, I witnessed someone getting a full-on mains shock from a 'live mic' and it's not a sight I'll ever forget, so please get your gear checked by a competent person as soon as possible.
I'm sure that Dave wasn't suggesting that you use a foam pop shield on the mic as some kind of stop-gap, temporary solution.