Bad bar electrical systems: Use a variable transformer on the supply?

[agedhorse]

Good point here— just to clarify— total voltage drop allowed at end of branch circuit is 5%. 3% max from feeder, 2% max from branch circuit for a total allowable drop of 5%.

Correct 5% total at the end of the branch.

 

[Rockbobmel]

Tripp-Power Conditioner LC1200View attachment 3447341 .. I use it for all my shows and for studio work.. Keeps it 120volts...I use many All Tube Bass heads and they run as they should.. My Ampegs use to go into "Fault" mode when the voltage dropped below 110 at some over used and under powered shows.. This was my fix and have been using them for years..

I got one of those for my hometheater/sound system. It clicks once in a while when I turn on the AC.

 

[gelinas666]

I got one of those for my hometheater/sound system. It clicks once in a while when I turn on the AC.

Probably a drop in power when the compressor turns on initially on the AC.. The unit will click when adjusting the voltage.. I notice mine going from "Green" to "Yellow" at some of the venues I play too...

 

[dannylectro]

It depends very much WHAT the real problems are with the AC supply.

For example, large amounts of noise can be generated simply by a neutral and ground being connected together or reversed anywhere in the feeder or branch circuits that are common to that feeding the supply. Not an uncommon fault where somebody forgets to remove a ground to neutral bonding screw from a sub-panel. This can cause circulating currents within the grounding system and induce noise.

The amps I have designed recently won't benefit from external voltage regulation anyway, it's already included and built into the power supply (including the main amp rails).

Licensed electrician here... the improper bonding of neutral to ground in sub-panels is a huge, common, and dangerous issue in many electrical systems, residential, commercial, and industrial. I’m not entirely sure what effect it has on power quality, but I do know that improper grounding/bonding issues can create severe (fatal) conditions that will not be solved by any of the solutions being discussed here, and are especially dangerous to people attaching homemade distribution systems to the main lugs of sub-panels. Don’t. Do. That.

 

[keyboardguy]

I got one of those for my hometheater/sound system. It clicks once in a while when I turn on the AC.

I have a couple of these also. If your voltage moves anywhere between 87 and 140 volts, this conditioner will pull it back to 120V. Priceless.

https://www.amazon.com/Tripp-Lite-L...e+conditioner&qid=1560745021&s=gateway&sr=8-1

 

[dannylectro]

To club/venue owners who may be reading this: if you want good power quality to your performance space, do these things:
1) From the main panel in your building, run at least three 20 amp circuits, in conduit with separate ground wires, to the stage. Two circuits to the rear, one circuit to the front. They should all be connected to the same phase at the main panel.
2) For lighting, assuming the use of modern, LED-based systems, at least one or two 20 amp circuits, run from the main panel of your electrical service.

Don’t run circuits from sub-panels unless a qualified electrician can verify, absolutely, that they are correctly installed, and grounded/bonded correctly.

 

[Nevada Pete]

Sounds like AC mains have tightened up considerably compared to how it used to be. No more hot tapping into the main disconnect!

I saw a guy get fried doing that at the Berkeley Community Theater while we were setting up for Tower of Power. I noticed for the last three or four shows one of the claws on Morpheus Light's distro we used to power the PA and the back line was missing that white plastic disc thing you use to tighten the claw down on the buss bar. So you had to use a big plastic handled screw driver to get that one cinched down. I wouldn't have done it, but then, I didn't like to do tap in's anyway because you can't use the one hand rule. I would do them, but only if there wasn't anybody else around who knew how, and was crazy enough to take on the job. Back then you were at least supposed to use these special two layer rubber gloves and stand on a rubber mat. Nobody I ever saw did that. Not even the stage electricians (at the venues that had one). So anyway, this guy was pretty new and for some reason or other he had been jonesing to do a tap in, but nobody would let him. I think the guy from Morpheus who usually did it wasn't there for that show, and so this guy evidently just waited until nobody was near by, and then took it upon himself to do it.

Okay, so before anybody could intervene and stop him he was evidently trying to get that one claw cinched down with the screw driver and somehow, he contacted the shank to the side of the disconnect panel cabinet. That would have been okay if he hadn't managed to contact the tip of the screw driver on one of the hot 100 amp 220 V buses! I think he may have thought that with the disconnect off so the panel door would open, those bus bars weren't hot. Surprise! There was this horrendous 60 Hz roar that was incredibly loud, and of course, a really bright arc flash. Then, silence. You could have heard a pin drop on stage. We all knew something bad happened. All I could think of was that somebody just got killed, but the guy got lucky. The force of the arc flash and his muscle contractions threw him backwards and he hit the wall about 20 feet away and collapsed on the floor totally unconscious. Both his eyes were rolled up in his eye sockets so far that all you could see was the white part of the eye ball! Every once in a while his body would quiver. But the amazing thing was his eye lashes would start fluttering so fast it was unbelievable! You can't believe how fast his eye lashes were fluttering! Then, they would stop for a while and start up again. It was kind of morbidly fascinating, actually. He was still breathing and his heart was still beating, so we left him be until the paramedics showed up and took him to Alta Bates Hospital. I think Jack and John Villanueva went to see him while he was hospitalized for a few days. He came through okay. Never saw him again, though. We found what was left of the screw driver. The shank was as big around as my index finger and was totally vaporized all the way up to just a few inches from the plastic handle!

The moral of the story is that electricity is just there, silently waiting to kill you.

 

[Redbrangus]

The moral of the story is that electricity is just there, silently waiting to kill you.

This isn't the venue to discuss it, but I don't think that is the actual 'take-away' from this admittedly horrific story. The situation described has so many wrong things going on that it's nearly incredible...and this is coming from a guy who's done a lot more sketchy tie-in's than I care to admit. (Back in my 'war years' of the 70's and 80's, doing name acts in backwoods roadhouses and dance halls.)

But yes, electricity can be lethal and should be treated with respect. I'll definitely second that.

 

[agedhorse]

I routinely worked with 120/208V and 277/480V up to 1200 amps. Either you are VERY careful, or you are stupid. There really are no other options. Arc flash burns flesh very effectively.

 

[Nevada Pete]

This isn't the venue to discuss it, but I don't think that is the actual 'take-away' from this admittedly horrific story. The situation described has so many wrong things going on that it's nearly incredible...and this is coming from a guy who's done a lot more sketchy tie-in's than I care to admit. (Back in my 'war years' of the 70's and 80's, doing name acts in backwoods roadhouses and dance halls.)

But yes, electricity can be lethal and should be treated with respect. I'll definitely second that.

Oh, I am so glad you agree that electricity can be lethal and should be treated with respect. That was supposed to be the point of my little story, with the intention of helping people avoid injury or death.

Frankly, I'm still uncertain what your point or contribution is supposed to be, since you never stated it, but there was nothing "sketchy" about our tie in to that disconnect, if that's what you meant. It may not have been the preferred practice to get it in there, but any tie in to a hot buss bar in a disconnect panel is highly questionable under any circumstances, and the practice is not even permitted anymore in many municipalities by the authority having jurisdiction over the fire code. I could have got it in there with no problem, and so could several others who were there at the time and had the proper training and experience necessary to perform the task. That particular task does happen to require that you know exactly what you're doing due to the fact that there is no room for error. That's all. The guy who got fried chose to act outside his designated area of responsibility in a situation where he was told more than once not to attempt what he did. There's nothing "horrific" about what happened. Arc flash burns and electrocution can definitely be horrific in the truest and most macabre sense of the word, but trust me, this situation didn't even come close to horrific. It was just another guy who refused to follow instructions and almost bought the Darwin Award. Nothing more. I thought the story might be amusing, and useful. That's all.

But since you insulted our tie in and further impugned the 'take-away' of my story, of all things, which I thought was the best part, too, while asserting that the situation described has so many wrong things going on that it's nearly incredible, that is, without saying just exactly what any of the wrong things are, and especially considering there aren't any, I don't think, anyway, and also, since I still don't feel like sleeping after being awake all night and generally happen to be in a typically arrogant and persnickety mood right now, as usual whenever this happens, I think, at least I'm pretty sure I take exception to your entire message. Unless I change my mind later, that is.

Well, for one thing we weren't in backwoods roadhouses and dance halls and I don't know about the "name acts" you were doing either. If they were name acts, what were they doing playing backwoods roadhouses and dance halls? Tower had formerly used Primo Productions until Herbie Herbert decided to use his big system for Journey, and we were asked to take their place. Tower was hot as a pistol at the time and could have had anybody they wanted do their sound. We were later asked, for example, to provide sound for Steve Perry's debut performance with Journey at the Old Waldorf in San Francisco at a historic private event for music business executives only. Steve Perry's performance that night is considered one of the monumental moments in music business history and launched what became to the best of my knowledge the greatest box office attraction of all time. But we don't know nothing?

On the day in question, Tower had just returned from a sold out show at the LA Forum (17,500 in attendance) with the Steve Miller Band and one other group I don't happen to remember just now (it all becomes a blur), they sold out the Berkeley Community Theater that night in their home town at 3,500 seats and could have sold out a second show except we were headed for Seattle-Tacoma for a show the next night, and then out of state. We didn't do no backwoods roadhouses or dance halls. I wish we had, though, because them backwoods roadhouses usually have a stairway around back and if you have a little jingle in your pocket you can have a little fun, too. Sometimes, if your with the band, you don't need no jingle. Usually. But it's not always convenient or even possible for everything to be perfect when your working on a schedule like that. The missing ABS white knob thing that tightens down the claw on a pigtail for tying in to an AC mains disconnect bus had nothing to do with that guy getting fried. If it was that important John Richardson would have replaced it, which did happen. Just not that day. You can short out a pigtail pretty easy on a bus bar in a disconnect panel too, you know, if your not paying attention. You just have to always be extraordinarily careful tying in power to a disconnect panel bus, and know exactly what your doing. There is absolutely <0> room for error.

We did literally hundreds and hundreds of big shows with the top box office attractions in the country, sometimes under very difficult working conditions, and that particular incident mentioned was the only time anyone associated with our production consortium ever got hurt, and that was only because the guy who got fried chose to do something he was told not to do. Well, except, that is, for the time I broke my nose and dang near took out one of my front teeth running across the arm rests of the seats at the Oakland Coliseum (before I became airborne) when we were late for a show because the rent-a-truck caught fire on Highway 17. That's when I opened my account with Roger Penske. Smartest thing I ever did.

Okay, so if you have something you think I need to know or that will be useful to myself or to other forum members and you don't think the Amps & Cabs [BG] forum where we're at now is the "venue" to discuss it, including your take-away from the story about the guy getting fried, why not start a thread in Live Sound [BG] and go for it? I may have had some fun with you, but I am actually interested in what you have to say, and I will read your message very carefully. Send me a PM after you read this message or "like" it (unless you hate it, that is) because I will probably delete this message after you read it. It's a little to self-bragging. Thanks for sharing your thoughts and feelings. And don't do any more hot tie in's. Okay!

 

[Redbrangus]

Thanks...I'll PM you in a bit.