Bad Power

[LouMan]

So what exactly can you do if the electrical system in the club is shit?

My band played a gig at a small club where the grounding was fucked. Every time I stepped up to the mic while holding my guitar, I got a nice jolt of 120volts to the chops.

We tried switching outlets, power cables, and even guitar amps- but nothing worked.

Is there anything you can do in those situations other than buying one of those Furman power conditioner things?

Thanks,
Lou

[malice]

I remember one dude who was playing guitar that was bringing a home made unit consisting in AC filters and a big Xformer.

About 250$ for the whole thing.

His Ac was filtered and completely isolated from the AC power of the venue.

Very effective. A bit heavy.

But not more expensive than a good stomp box.

malice

[Bob Olhsson]

The big thing on stage is to try and have everything plugged into the same circuit so you don't get your a** fried!

Here at home I have everything going to one six-way. It eliminated all kinds of problems.

[pounce]

one quick note, we are going to have a tutorial on live power coming up very very soon. these things will be more fully addressed there, but since you brought it up...

it could be argued that it is the responsibility of the venue to have adequate clean power available for the performers. sadly, this is not always the case (mostly in smaller venues like bars). for instance, back when i actually was on the gigging side of things i had a sampler go down onstage because the bartender used a blender and it zooked our stage power for a second. shit. not a good thing. and this was a cranky old sampler that took a while to reboot.

so the answer? well, if the bar is providing questionable power, than the next best thing is to bring something to help rectify that. enter the furman. (or equivelant).

were i you, i would absolutely get a line conditioner of some sort, something nice and beefy. possibly even a large ups. at my home studio, i have a furman it1230 providing balanced power to my studio on a seperate circuit from anything else in the house and my computers all have ups's on them. in larger live situations, we tie three phase power (three hots, a neutral and a ground) into processing and power distribution for sound, lights, video, etc. - and they all get seperate ones tied in from seperate high power disconnect panels.

assuming in the bar you won't tie in your own distro to the electric panel, you'll want to have some kind of protetion for you and your gear. granted, lots of bands don't bother. i would, though. things like...

http://www.furmansound.com/products/pro/reg/reg6.php?req=acv

or

http://www.furmansound.com/products/pro/ups/sb_1000.php

which is like a great insurance policy for your gear, as well as likely assuring that ground issues and so forth don't get into your live sound. it would be better if you didn't have to do this, but i still would be reluctant to presume that the bar will have you covered. i'd rather bring stuff like this, and i assure you if i found myself playing out again it would include some type of power regulation.

[LouMan]

Thanks for the replies.

I figured the power conditioner thing would be the solution.

We were going to try the single outlet method but it was gig time and we didn't have the time to rewire everything. The weird thing was that it only started happening when I plugged in my guitar amp. The bass player and the other guitar player's amps were fine.

Thankfully, this wasn't a place that we play at regularly.

[Spock]

I've not seen dirty power too much. Most of the time it has been massive hum fields from something near to my rig. Some neon signs are just murder for RFI. If the club/bar is wired correctly in terms of grounds and neutrals, then you shouldn't have a problem. Using one circuit fixes things because you have just one G and N. Putting things into a big iso transformer wil also work, but as said are heavy, and now your G and N are on the output side of the xformer.

If you can't do anything else, then make sure all the audio runs are xlr, transformer ballanced, and use telescoping shields. If you never tie equipment grounds together along the audio path, you can't have a ground loop.

Please don't go lifting the ground on the power cord. While it might fix your problem, you have just created a major saftey problem.

[dwoz]

I have unfortunately experienced more than my share of "brown" power.

In the USA, that's somewhere around 100 volts or so at the wall.

Basically, you end up with very quick distortion thresholds in equipment that works, and you end up with lots of stuff that flakes out, or even dies. Lower voltage means you're pulling higher amps, and it isn't difficult to go over the rating of some gear.

I've also seen very strange power problems when there is industrial 3-phase coming into the building, and its improperly balanced.

dwoz

[Spock]

I've not run into much low voltage in this area of the country. Of course I was one of the guys that made the power.

Right, a real badly out of whack 3 phase will screw things up. What is worse is when someone uses the wrong type of xformer on the load side. They should be delta input and Y on the load size. I worked for a while at a place (built in 1720s) that had delta delta. So the ground was floating and changed based on the un-equal loads on the phases. Yuck.

[AxeSlash]

Novice Telehandler driver.

Large 3 phase generator (we're talking camlocks here).

Many thousands of pounds worth of line array and FOH gear.

Cables running across where they shouldn't have been.

The morning of show day.



Let's just say that there was one hell of a repair bill and some of the fastest Ford Transit driving I have ever witnessed in my life.

I don't know if the LX boys got away with it, I think they were on a separate geny, but if it had been the same one...there would been about 100 moving heads dead as a doornail.

Other than that I don't think I've had many power problems. Actually there was a local pub venue that seems to give some people a phantom-style shock from the vocal mics - I think it's an earthing/cabling issue somewhere along the line.

[pounce]

the "shocking 58" is an indication of a grounding problem and really should be addressed, but seing as how it's unsurprisingly a pub gig with that type of trouble they may not get to doing anything about it. which is a shame because that's an indication of incorrect and possibly dangerous wiring somewhere within the system. perhaps a lifted ground in the wrong place.

[ggunn]

Does your guitar amp have a three pin power cord? If not, get it converted; it could save your life.

Something else that could save your life is a circuit tester. Radio Shack sells one for just a few bucks; it's a plastic block that plugs into an outlet, and it has 3 LEDs on it that light up in various patterns that tell you if the outlet is wired correctly or not. It has a chart printed on it that tell you what every pattern means. Hot and neutral reversed, for example, can be deadly.

There really are two separate issues here. "Dirty" power usually means a noisy or distorted sine wave and/or low voltage, and the problems it causes are usually not life threatening, just noisy in audio gear. Bad or improper wiring, OTOH, can kill you.

[LouMan]

Does your guitar amp have a three pin power cord? If not, get it converted; it could save your life.



The amp is a late model Rivera with a 3 prong plug. We tried a different power cable, and even a different guitar amp altogether. but the problem wouldn't go away.

The outlet tester is a great idea. I'll have to pick one up.

[pounce]

i hadn't gotten to writing a new thread on what to have with you on gigs, but i assure you a power tester like we are talking about here is on the list. i have a couple of them, one always at home and one always in my gig bag.

[G. Hoffman]

the "shocking 58" is an indication of a grounding problem and really should be addressed, but seing as how it's unsurprisingly a pub gig with that type of trouble they may not get to doing anything about it. which is a shame because that's an indication of incorrect and possibly dangerous wiring somewhere within the system. perhaps a lifted ground in the wrong place.



It is USUALLY a ground problem. It can also happen when some dumb as fuck "electrician" wires hots and neutrals backwards, or if you are pulling power for your amp from different power than the PA.

Either way, get it fixed.

i hadn't gotten to writing a new thread on what to have with you on gigs, but i assure you a power tester like we are talking about here is on the list. i have a couple of them, one always at home and one always in my gig bag.



I assume a good multi-meter is also on that list, yes?


Gabriel

[burnsy]

I suppose then im quite lucky that my venue isnt too bad about wiring that I have come across being a club and all, but what concerns me is the lack of PAT testing that goes on in smaller venues. Come january my dvd collection is outand we are going through everything the theatre physically has electrical wise which is always good to clock up hours. Do you lot have your kit pat tested a lot ?

Also I recently noticed a hum in the PA and a bit of a bleed through on my desk when the faders are down is there any solution to the bleed through ? Desk is a soundcraft spirit live 16 channel (l+r+m)

Cheers

[AxeSlash]

PAT testing to some extent is a false indication of the state of the gear. Legally it only has to be done once a year, but any cable can get pulled or knackered in some dangerous way on a gig, and no-one will be any the wiser until they're in hospital.

I suppose it's not as bad in a set venue where stuff doesn't move much, but for a touring sound company, the only way to be 100% safe would be to PAT test every bit of kit and every cable after every gig. Which no-one I know has the time or manpower to do. External visual checks are doable, but there's no way we're gonna be taking apart every 16A socket and plug that comes back from a gig to check that none of the cables have been pulled out.

Electrical safety in this business is a bit of a grey area I think (certainly here in the UK). People put all their faith in PAT testing and are really anal about it, when what they SHOULD be anal about is how well the gear is checked in and out and how well protected the mains distros that people cart around are. There's a lot of ignorance in that respect - 100mA RCDs, for example. Most of our guys weren't aware that you need to have a 30mA RCD on your system because it takes less than 100mA to kill. I've even seen distros without any sort of earth leakage protection.

And then there's the whole IP rating of ceeform connectors that a lot of people are ignorant of.

I think I've just cracked open a mighty can of worms there.

Oh and don't get me started on lighting rigs and rain...

[ggunn]

Excuse my ignorance, but what is a PAT test?

[pounce]

portable appliance testing

[ggunn]

portable appliance testing

What kind of testing? Leakage, grounding hazard, that sort of thing?

[Spock]

It's amazing the junk you can find. I was working in a computer room and we keep having all kinds of strange problems. The vendor of the equipment was trying everything to fix the problems. The finally put in a power monitor as a last try at something, it logged all kinds of problems.

Problem was we couldn't touch the UPS or PDUs, union shop. We couldn't even get the vendor of the UPS and related equipment in, the union insisted that they had to be in the middle of it to make sure "it was done right"

We get the UPS vendor in and he checks out everything and is tunning things up, get the remote monitoring working. He shows me the monitoring system, and I flip by the stuff it can show me, and I stop dead we it says PDU #3 has 7 amps of ground current!!!!!

I ask is that for real or is the unit reading wrong. We go into the room and he measures it directly, yup, 7 amps.

The guy that built and wired the room had reversed gounds and neutrals all over the place. We had to take the whole place down for a weekend so that every under floor box could be traced down, opened up, and fixed if needed. About 50% needed to be fixed.

Guess what, no more odd problems with the equipment after that.

[pounce]

i guess that is another good reason for the ground wire to be green. a lot easier to keep things straight that way.

[jfee]

I've also seen very strange power problems when there is industrial 3-phase coming into the building, and its improperly balanced.

dwoz

I organized a big show when I was fairly young. We had an electrician wire up a seperate panel so that we could get all the juice we needed for the production. He was wiring our panel to the three-phase coming into the building. Our panel was single phase but for some reason he thought it was three phase (which I can't possibly understand) and ended up wiring the ground from our panel to the second hot phase coming into the building.

Myself and a buddy set stuff up for about 3 hours. We were getting shocks off of stuff and couldn't understand why but didn't pay much attention to it. We powered everything up (big A&H console, EAW speaker array, a couple dozen fancy Martin Robotic lights) we were testing stuff and despite a couple weird little things it all worked perfectly and then 30 minutes later.....kaboom!

The place went dark. It was such a large bang I figured we blew most of the drivers in the speakers....Then some kid tells me he saw fire coming out of the back of the console. I was making plans to leave the country at this point.

In the end it wasn't so bad. We figured out the power issue, everything powered back up except for a few pieces with blown fuses and the furmans were all fried.