Microphone shocking

[Marvin]

Our singer is saying that she's getting an electrical sensation when holding the microphone. 

 

Someone suggested that the phantom power might be on on the mixer. However,  I can't remember seeing the phantom power light on on the mixer and the guitarist said he checked it was off.

 

The sensation is all the time. She's tried a different mic, changed the cable,  stood a a rubber floor mat, not stood on the mat. Still the same.

 

The phantom power seemed the obvious culprit but apparently not (unless there's a fault in the desk).

 

Any ideas?

 

Ta.

 

Edited August 22 by Marvin

[Chienmortbb]

This is odd. There is no reason that the singer should get a shock from a mic unless there is a fault on the mixer and that would be unusual. You need to measure the voltage between the mic grille and earth. It should be very small, millivolts ideally.  

[Bill Fitzmaurice]

This was common in the days before 3 wire mains cables were used, which insure that all devices are properly grounded. But it usually presented a problem only if one was holding a guitar and touching the mic. Just holding a mic should never present a problem. Even if the mic body is receiving current she would have to be a path to ground to feel anything. Have you had someone else hold the mic to see if they feel it? 

[Stub Mandrel]

I've had this a couple of times.

 

Not mains shock, but a lip tingle - being moist and crammed with receptor cells the lips are very sensitive to static and fairly low potentials.

 

These days a cause can be double-insulated gear 'floating' above ground, one cause can be both ends of a signal chain with a ground lift perhaps made worse by leakage across ans SMPSU.

 

Double insulated chargers can do this.

 

So perhaps start by checking the mic's ground is continuous with earth.

[Newfoundfreedom]

Get a wireless mic adapter. Solved the problem for me. No chance of current running through cables to the mic.

We have a 2 wire negative earth system here in Bulgaria and I wouldn't trust putting my body parts anywhere near it. Fully wireless for the bass and mic. 

[JapanAxe]

9 hours ago, Stub Mandrel said:

I've had this a couple of times.

 

Not mains shock, but a lip tingle - being moist and crammed with receptor cells the lips are very sensitive to static and fairly low potentials.

 

These days a cause can be double-insulated gear 'floating' above ground, one cause can be both ends of a signal chain with a ground lift perhaps made worse by leakage across ans SMPSU.

 

Double insulated chargers can do this.

 

So perhaps start by checking the mic's ground is continuous with earth.

This.

 

I’ve measured (and felt!) 70-80V between the output of a 9V switched mode wall wart and ground. Earthing the connected device made the problem go away.

[Marvin]

On 22/08/2025 at 20:12, Bill Fitzmaurice said:

This was common in the days before 3 wire mains cables were used, which insure that all devices are properly grounded. But it usually presented a problem only if one was holding a guitar and touching the mic. Just holding a mic should never present a problem. Even if the mic body is receiving current she would have to be a path to ground to feel anything. Have you had someone else hold the mic to see if they feel it? 

 

No, we haven't tried someone else holding the mic.  It'll be the next step, as the desk is new, the mic is new as was the cable at the last practice. 

 

 

[Phil Starr]

This isn't right or OK. Something electrical is going wrong and needs fixing. It isn't static which will discharge once and go away and doesn't ususally build up on properly earthed equipment.

 

The most common cause is a floating earth. We all trust the central pin on our plugs but it is connected to earth by many metres of cable in the walls and under the floor via loads of connections which may have been wired by the apprentice last thing on a Friday 30 years ago. You'll have some resistance between earth at the entrance to the building and this will be greater with any corroded or poorly made connections. A voltage will devlop between the earth on the plug and if the supply in the room is on spurs or two different ring mains then there may well be a voltage dfference between the earths on the two circuits. You can often measure a difference between two earthed appliances as they are both 'floating'. I run all our electrical gear off a single socket whenever I can, much easier nowadays with LED lighting and more efficient amps and speakers. That means the earth may be floating but if every earth is at the same potential you won't get shocked. The highest difference I've measured is 47V between earths in the same room. Mostly it's less than 10V which gives only a tingle.

 

There can be other problems with the mains wiring. I've had cables shorting within walls and problems with buildings with circuits within rooms on different phases. Not every electrician is a genius unfortunately.

 

Obviously the floating earth is a problem with the room so it should only happen in certain venues or practice rooms

 

It could however be that something is shorting within a faulty bit of gear and that needs checking if you can find what it is

[Beedster]

1 hour ago, Phil Starr said:

This isn't right or OK. Something electrical is going wrong and needs fixing. It isn't static which will discharge once and go away and doesn't ususally build up on properly earthed equipment.

 

The most common cause is a floating earth. We all trust the central pin on our plugs but it is connected to earth by many metres of cable in the walls and under the floor via loads of connections which may have been wired by the apprentice last thing on a Friday 30 years ago. You'll have some resistance between earth at the entrance to the building and this will be greater with any corroded or poorly made connections. A voltage will devlop between the earth on the plug and if the supply in the room is on spurs or two different ring mains then there may well be a voltage dfference between the earths on the two circuits. You can often measure a difference between two earthed appliances as they are both 'floating'. I run all our electrical gear off a single socket whenever I can, much easier nowadays with LED lighting and more efficient amps and speakers. That means the earth may be floating but if every earth is at the same potential you won't get shocked. The highest difference I've measured is 47V between earths in the same room. Mostly it's less than 10V which gives only a tingle.

 

There can be other problems with the mains wiring. I've had cables shorting within walls and problems with buildings with circuits within rooms on different phases. Not every electrician is a genius unfortunately.

 

Obviously the floating earth is a problem with the room so it should only happen in certain venues or practice rooms

 

It could however be that something is shorting within a faulty bit of gear and that needs checking if you can find what it is

Very good post. I never assume wiring in any building is safe, speak to any domestic sparky about the stuff they’ve come across …..

[police squad]

get yourself a mains tester, the one you plug in and it lights up telling you it's safe

you may have a dodgy extension lead. I dep in a band where the guitar player always got a tingle from his mic. He doesn't now, it was a dodgy extension lead

[godathunder]

44 minutes ago, police squad said:

get yourself a mains tester, the one you plug in and it lights up telling you it's safe

you may have a dodgy extension lead. I dep in a band where the guitar player always got a tingle from his mic. He doesn't now, it was a dodgy extension lead

Sparks (semi retired) here - absolutely seconded. NOTHING gets plugged in until the wall socket/extenion lead has been tested with something like this.

https://www.screwfix.com/p/lap-16a-socket-tester-230v-ac/91596

these are a fiver at the moment and are so simple to use that even the drummer can use it - theres no excuse to not have at least one stashed in your gigbag

 

theyre not a panacea and dont check useful things like actual voltage present and cant detect a neutral/earth swap but they will give you a good indication of the general safety of that outlet

 

very often cheap switch mode power supplies leak all sorts of nastiness but thats a little outside the remit of the end user to deal with.

[police squad]

5 minutes ago, godathunder said:

Sparks (semi retired) here - absolutely seconded. NOTHING gets plugged in until the wall socket/extenion lead has been tested with something like this.

https://www.screwfix.com/p/lap-16a-socket-tester-230v-ac/91596

these are a fiver at the moment and are so simple to use that even the drummer can use it - theres no excuse to not have at least one stashed in your gigbag

 

theyre not a panacea and dont check useful things like actual voltage present and cant detect a neutral/earth swap but they will give you a good indication of the general safety of that outlet

 

very often cheap switch mode power supplies leak all sorts of nastiness but thats a little outside the remit of the end user to deal with.

I spent the first half of a gig getting shocks from the mic AND my behringer P2 as it was touching my skin.

I finished the 1st set with no IEMs and no backing vocals

I then plugged my bass amp into a diffferent socket with my extension lead, not the DJs and problem solved

I then bought the mains tester and have since used it at every gig (and not had any problems either)

[godathunder]

and while Im being a preachy know it all / ersatz screwfix salesman - an rcd socket adaptor is a good idea too. Really theres no excuse for the venue not to have rcd protection at the board but back here in the real world.............

https://www.screwfix.com/p/masterplug-13a-fused-plug-in-active-rcd-plug/44855

 

and yes, if your gear/cabling is suspect there is a chance of it activating and embarassing silence following but thats temporary and preferable to the permanent silence that may follow if a fault occurs without one

[Woodinblack]

There is a gig we play in a semi permenant outdoor area next to a pub. A tthe weekend the guitarist was getting shocks through his guitar, but the worst one was last year when we were there when it had been raining, the guitarist sat on the floor which had a puddle on it, and then when singing got a shock to his mouth (which stopped him singing).

I have tested it with a tester, it says it is fine apart from the voltage being at 209V (and having 1v N-E), but it certainly isn't right there. 

 

[Dan Dare]

You mentioned holding the mic' to test it. Don't. Just touch it with one finger. There's a chance that you could freeze and not be able to let go if you get a shock.

 

Phantom power is 48v. Too low to give the feeling of a shock. Don't use your gear until it has been properly checked over and invest in a tester, as others suggest. Faulty extension cables are an obvious suspect. Does it only happen at one venue/place? If so, their wiring may be faulty. I've found faulty wiring in several pubs over the years, thanks to my mains tester. The landlord had probably got a customer to do a bit of electrical work in exchange for a few pints. It happens.