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Grounding problem at lastnights gig

68Goldfish

68Goldfish

Nov 4, 2006
2,810
5,117
57
Port Orchard WA
#1
Hmm, not sure if this is the right forum or not but maybe I can get some help here. lastnight my band played at a gig in another town at a bar we've not played at before. Got there, set the gear up (had to bring our own PA) and everything was going fine. That is untill my singer tried a mike check, Zap, he got the shock of his life. If you even touched a mike it was like sticking a screwdriver in a wall socket. That is, as long as you had a guitar on. If you didn't have a guitar you didn't get shocked. This is the same exact equipment we use at the practice pad with no problems. We moved some plug in's around with no improvement. We eventually took the metal ball part of the mikes off and it worked for singing but you still could not touch a mike. The bar has bands playing there every weekend and the owner said it's the first time she's heard of it. Any idea's on what the problem could have been? We've never had this happen at other placed we've used the same gear at. I'm just wondering what if anything we could have done to resolve the problem.
TIA TB
:bassist:
 
#2
Thinking about it now the guitar player just got a 63 fender tremelux or vibrolux or something of that sort and it's only the second or third gig he's used it on. Wonder if there could be a problem there. I was using a later model GK so probably no problems there.
 
#4
Also, while you might not have gotten killed -- yet -- in your rehearsal space, the fault of those old amps can depend on which way the two-prong plug is plugged into the wall outlet. The amp must be quarantined until a tech can look at it.
 
#7
I don't care if it's a rig I've used 1000 times in a room I've worked 100 times. I don't care if Jesus Christ himself checked the electrical system first...

Grab the strings with your left hand, tap the back of your right hand on the mic. Every effing time.
 
#10
There's several good ways to check for that before you start. NEVER grab anything, but use the BACK of your hand. That way if your muscles jerk, you'll be jerking away from the mic. But the better way is to use a small VOM to check for volatage across the mic and your (grounded) strings. Even better, get a cheap plug-in socket tester. It's got three prongs and three LEDs. It shows if you have the right grounds at the outlet, and you'll know before you even set up anything.

Cheap insurance!!

John
 
#11
At the risk of repeating what others have said, (but hopefully more succinctly):

All equipment shall have three-wire AC cords, and the ground pin shall be intact. (If I find one in my venue w/o a ground pin, we gonna have a talk.)

All extension cords and power strips shall be three wire and shall have the ground pin intact. (If I find one in my venue w/o a ground pin, I immediately unplug it and cut the connector off so that it cannot be used.)

All equipment shall have the "death cap" removed and the ground switch disconnected.

If the "back of the hand" test still gives you a zap, plug your amp into the same AC outlet that the PA is plugged into.

If you still get a zap, either your amp, the PA, or the venue wiring has a problem.
 
#12
I carry a circuit tester to make sure the outlets are wired correctly.

It might also be useful to have a portable GFCI, like is used for power tools. If anything plugged into it is leaking to ground, the GFCI will trip. At the very least, it is a safe way to help you find the offending component. These are prone to nuisance tripping, so I wouldn't typically use one with a band as a matter of course, but it might still be useful at times like this.
 
#14
In the UK we use what is called a Residual Current Breaker, or RCB, that trips if a voltage between live and earth is detected. They are generally used with electric lawnmowers and hedge trimmers where you are in danger of cutting the power cable if you're not careful, but I keep one in my gig bag because back in the day, before they existed, I nearly got myself killed at the age of 14 when my amp was earthed and my friend's wasn't and that is not experience I care to repeat!!. The British Voltage (240) is more than double that of the US.

BTW - I recall a story I was told that the engineers at the Vickers Aircraft company in Weybridge used to "bait" the new apprentices by holding the bare end of an electrical cable and saying "Pass me that screwdriver, will you?" ....
 

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