Shocking Review

leftyguitars · Post by **leftyguitars** » Tue Nov 15, 2005 9:52 pm

Peter, I have been doing stage electrics (and house wiring) for over 30 years, to get to a "live" situation like this you need to have two faults. Firstly an earth fault (bad earth connection or broken wire) and secondly a live to earth fault (although it could be a broken live touching earth or broken earth touching live fault in a plug for instance). The bad earth can be in the house wiring or in one of the appliances being used. The live to earth fault will most likely be in one of the appliances. If you are using an extension lead check that it is ok as I have found that extension leads cause more problems than anything else. Do you have RCD (Residual current device) protection? (often this is a portable plug/socket which is placed in the supply line). This would certainly show you if there is a problem as well as saving your life! Is the supply fused? if so what is the rating? but be aware that fuses only protect the wiring or appliance - they will NOT protect the user, only an RCD will do this.
Please also be aware that if you have a "live" mic. and hold it with one hand, and then mute your "earthed" guitar strings with your other hand the current passes across your heart with the likely outcome that YOU DIE. I am not scare-mongering - I have known it happen!!!

***This really has to be sorted out urgently, as there could be a serious risk of electrocution***

ken_j · Post by **ken_j** » Wed Nov 16, 2005 4:31 am

"but be aware that fuses only protect the wiring or appliance - they will NOT protect the user"
A GFI (ground fault interrupter)if installed would prevent a shocking. In the US, not sure of Canada, your white wire (common) is tied to the ground lug in the circuit panel. If you have city water, in this area, the ground is attached to a water pipe. There is also a jumper at the meter due to its isolation. If you have a well there is a copper grounding stake. I would check all of these areas. Although a problem with an amp seems more likely to me you can't be too safe.

leftyguitars · Post by **leftyguitars** » Wed Nov 16, 2005 7:13 am

It looks like your GFI is the same item as our RCD. It measures the outgoing and return currents on the live and neutral lines, if there is a discrepancy of more than 30ma (in our case) it trips the supply.

admin · Post by **admin** » Wed Nov 16, 2005 8:02 am

Ken and Peter. Thanks for your comments.

I can certainly tell you that I have had enough talk about GFI's and and Arc Fault circuitry to last me for a few months.

In the end, the primary problem was an intermittent shorting of an AC receptacle. Sometimes it worked and sometimes it shorted out. I became one of the short people over this hair-raising experience.

It was not immediately obvious, but I insisted on a new receptacle and voila, the problem went away. I won't go into all the details as you will fall asleep before I am through. Suffice it to say, that I am not getting the shock of my life anymore when at the microphone. There is still some talk about the requirement for another GFI.

ZZZZZZzzzzzzz but no more Zaaaapppp.

Thanks again, I appreciate your advice.

bitzerguy · Post by **bitzerguy** » Wed Nov 16, 2005 8:20 am

I have installed GFI outlets or GFI protectors in every branch of the 110V in my house. Each GFI protects the entire branch circuit of outlets and switches. At $15-$20 each, they are an inexpensive way to protect you and your loved ones. I had to install 10 of them.

...Dean

soundmasterg · Post by **soundmasterg** » Wed Nov 16, 2005 12:45 pm

Peter Levett, what could cause a lot of hum when a tube amp is used in a particular location? What I'm referring to is my uncle's shop in Washington that was built within the last 5 years. Any tube amp that is tried in there has a loud hum, yet all the amps are fine here at my house. We've tried turning off all lights and any other electrical things out there, yet the hum persists. Did they not ground the building correctly or something? Is there any way to check?

leftyguitars · Post by **leftyguitars** » Wed Nov 16, 2005 10:11 pm

Greg, does the hum sound to be around 60hz? if so it could be a bad earth (ground) either in the socket circuit or in the building itself, are there any dimmer switches on any of the lights in the building as this can cause hums or buzzing? I have on occasion known lighting dimmers to cause interference even when the light itself is turned off (with the dimmer on minimum rather than switched). The shop isn't near anything that could cause interference (a large electrical transformer on a pole nearby for example). I don't know a great deal on US installations as I am in the UK and trained on UK systems only. Is it possible to plug the amp into a different circuit, or a (very) near neighbours supply to see if it is any better? The supply isn't coming from a generator is it? as these can cause problems too. Do you have things connected to different sockets which are then connected to each other (by signal cables for example) as this can cause earth loops which will hum (at 60hz). Whatever it is, don't be tempted to lift the ground connection anywhere on the mains side as the results can be fatal.

soundmasterg · Post by **soundmasterg** » Thu Nov 17, 2005 1:25 am

Peter, yes it does sound like 60 cycle hum. Its not as loud as if an amp needed caps, but it is quite loud. No dimmer switches in the building, and all flourescant lights. Turn them off and no difference. He lives out in the middle of nowhere, so nothing to interfere. When we plugged in, we were going direct to the wall plugs. If I recall correctly, everything is quiet in his house, but 50 feet away where the shop is, it hums. It must be a bad earth ground I guess. I'll be up there for thanksgiving, so I can try it again and get more info.

admin · Post by **admin** » Thu Nov 17, 2005 1:53 am

Greg: Florescent lights can be a big culprit, at least in my experience.

leftyguitars · Post by **leftyguitars** » Thu Nov 17, 2005 5:33 am

I agree, fluorescent lighting can cause big problems. Knock the lights off and see if that cures it.

soundmasterg · Post by **soundmasterg** » Thu Nov 17, 2005 3:57 pm

If you'll notice, I said that turning off the lights didn't make a difference.

I'll see if I can notice more about the problem on thanksgiving when I'm up there next and shed more light on the situation.

jnbass · Post by **jnbass** » Fri Nov 18, 2005 8:03 am

triode · Post by **triode** » Thu Nov 24, 2005 8:56 am

I have played gigs in all types of establishments. Usually with bad AC power. The noise comes from:

Fluorescent Lighting, bad ballasts in the lighting too.

Refrigerators, microwave ovens, television sets, motors, air conditioners, heaters, cell phones, radio transmitters, etc.

Noise also comes from unshielded light dimmer switches and cheap stage lighting setups. They use very cheap and noisy diodes in the attenuation circuit that generates a nasty square wave in the AC signal path that makes radios buzz, pickups hum and amps buzz.

I have eliminated most of this noise by using high quality shielded guitar cables and using a line conditioner for the amp, pedals and PA. I use the Fuhrman Power Pro Plus. This thing significantly reduces the noise, cleans the AC and harmonizes the whole band so every one is on the same phase.

They can be bought from music discounters for about $220-240 street price.

They make your music sound better even at home.

jnbass · Post by **jnbass** » Sun Nov 27, 2005 6:05 am

the building wired for 3PH?

had a problem before with industrial locales...

admin · Post by **admin** » Tue Dec 13, 2005 12:17 am

Well my shocking microphone problem has returned. It seems that it is worse the longer I play my guitar, that is there is no shock at first but it gradually builds up over a minute or two and then zap! The electricians claim that the voltage is ok. I switched microphone cables and microphones but the same effect was replicated. I am using a powered mixer. Could this be the culprit? Phantom power?