why do i keep getting shocks off my microphone?

[bearsmith3685]

for the last few weeks i have been getting electric shocks off my microphone every time my lip touches it.it only shocks me when i have my guitar on though and it never used to do this before.does anybody know a reason why this would happen?

 

[ylo]

OUCH. I hate when that happens. Sounds like you have your grounds reversed between the PA and the guitar amp.

Is one of these a vintage amp (60s or so ) with 2-prong plug? If so, rewire it with a 3-prong plug. Most old 2-prong amps have a ground reverse switch to fix this problem, but putting in a 3-prong is much safer.

I suppose you could also have a bad or missing grounding capacitor in your guitar. See the guitarnuts web site for details on correct guitar wiring.

 

[bearsmith3685]

no my amp is pretty new-i use a road king and ive just bought a prs 513 so i wouldnt of thought that there would be any faulty capacitors-do you have any other suggestions because doing a gig is becoming a very painful experience!

 

[allcountyfair]

SAME PROBLEM HERE! i just got my guitar all resetup they ran through the grounding and all the electronics and fixed it all...now almost every time in practice i get a shock off my SM58, it doesnt happen if i sing with the SM57. Every practice i try to have every PA wire as far away as any of my amp wires but lately i cant solve it...annoys the hell out of me!

 

[chedgeco]

It's either the guitar rig (amp) is not grounded or the PA is not grounded. You have become the connection to ground for one of those two rigs.

It could also be the AC socket that the PA or the guitar rig is plugged into, which would result in the same situation I mentioned above.

Go down to Radio Shack and get a ground fault tester (about $3.00) and test the AC sockets that the PA and the guitar rig are plugging into.

Do not use those ground lift plugs that change your 3 prong AC plug into a two prong AC plug, if you do expect to get shocked.

Make sure you test those multi outlet devices as well and any extension cords with that same $3.00 ground fault tester.

Chris... 8)

 

[ylo]

I second the idea of getting a ground fault tester.

Also make sure that your amp and PA are plugged into the same outlet if possible, not outlets at different ends of the stage. One of these outlets could be miswired. Wiring faults are common in old pubs.

 

[Ken j]

Something else you might try in addition to the above advice is to have the PA and guitar amps pluged into the same leg of the of the power source. If you look at incoming power there are three wires, common (ground) and two power leads (legs). From either of the power legs to common is 120volts to each other you have 220 volts. I have had an instance where I can have two amps pluged into different outlets that were on opposite legs and end up with nasty ground hums. I woudn't be supprise if this can also cause a shock.

 

[stokes]

If there is a ground switch on the amp or PA or both they have to be set so the two are in phase.If neither have the ground switch,it is likely that the outlets are wired out of phase.Like someone else said already it is fairly common to have outlets wired out of phase.Sometimes these ground switches are marked "polarity".Adjusting one of these will likely cure the problem,that is what they are for.

 

[ylo]

. . . From either of the power legs to common is 120 volts to each other you have 220 volts . . . can have two amps on opposite legs and end up with nasty ground hums . . .

This is an example of bad wiring at the gig venue. This sort of thing has been known to cause destruction of computer-based keyboard and synthesizer gear. You should be able to catch this 220 V split ground problem with a ground fault tester. One challenge to minimizing this by using one outlet for all gear is that you can easily over draw and cause a house fuse to blow.