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[Steve-White]

Two stories to tell -

First at an historic vaudeville/movie house of the "atmospheric" motif, so the original electrical service has a very "Dr Frankenstein's lab" vibe, although much of it was decommissioned and replaced with modern service (red herring alert).  In the update the architect specified 208/120 100 amp service for SL and SR (no herring here), below stage level (floor pocket) in power vaults (the orchestra pit and seal room were between them).  Popular band from the 1970s, not my show, call from PA provider about hum/buzz.  "PA is quiet until we connect the monitor split; monitors are quiet until we connect the PA split.  I've used every Pin 1 lift I have, do you have 8?"  PA power is SR, monitor power is SL.

Second is personal, and how I nearly did great bodily harm to another PA provider after I recovered.  "Rock on the Tarmac" at general aviation airport, we're providing additional subs, power, and processing for the subs.  Airport electrician wires in 2 feeders to 2 circuit breakers for 120/240v 100 amp service in a brand new panel in a newly built hanger.  Most of the PA was on one distro, and our sub power and DSP was on a second distro.  Another of those "it's quiet until we put them together" problem.  Audio isolation transformers only changed the sound of the hum; pin 1 lifts were more successful.  I then ask the PA provider if the neutral and ground in each of his distros are unbonded.  "Of course!"  After the show, I do the disconnect at the panel as the electrician is at the other end of the ramp, disconnecting food vendors.  On the second service, the electrician (for reason I'll never understand) stabbed the neutral into the bus bar from the Line bus side.  When I removed it, the neutral feeder wire grazed a line bus 'finger'.  The result was a loud bang and flash (neither of which I remembered immediately after), and a coworker leaning over me asking if I was okay.  Eventually I got up, ears ringing, and followed the feeder to its distro.  I opened the distro, found the neutral and ground bonded (hence the arc flash), so I took my diagonal cutters and installed high impedance air gaps in every conductor, put the cover back on, and vowed to kill that SOB.  Revenge is a dish best served cold and Mother Nature took care of for me a few years later.

So anyone want to guess the problem in the lovey atmospheric theater?

All of this was around 25-30 years ago, and both directly changed the ways I deal with show electrical distribution, how I specify power needs, and how I work as a show electrician.

I've been fortunate "thus far".  One thing I do differently than in the early days is the use of a proximity voltage tester.  I make sure it's working on a known live circuit and methodically check everything to include face of rack gear.

Ya can't be too careful with electricity or any other aspect of what we do.  Loading trucks, rigging, what-have-you - it can be real dangerous.

[Ike Zimbel]

Chasing hum in a situation like that, most of us would have had a similar experience and never thought to check the ground at the panel - it's assumed...   

I'm still in touch with the guy that owned the audio truck on this gig. I sent him this piece, and he sent me back an e-mail with a whole other horror story that I knew noting about. Here's an excerpt:
"...we were powered by a generator that had been Supplied by xxxxxxxx that was rented from a subcontractor who had rented it from a subcontractor. After many hours with no sleep I was pretty happy with everything eventually and then a few hours before showtime things started to sound . . . weird. And weirder. And even more weird. Finally, I went over to the genny but couldn’t find an operator or anybody who knew where the operator was. I climbed in the back and took a look around and the AC I was getting was 94 V at 47 cycles. “Ahh” I said (or maybe it was “aarrgghh”) as I raced back to the truck and threw the breaker. After a while, the operator showed up wreaking of dope, and we got the generator refueled, and things went back to normal, sort of!"
He eventually sold that truck around 1986, and for the next few years I worked for the new owner as lead-technician and truck driver. One of the things I did, about a year in, was install a Sola isolation transformer on the mains inlet.

[Scott Holtzman]

Two stories to tell -

First at an historic vaudeville/movie house of the "atmospheric" motif, so the original electrical service has a very "Dr Frankenstein's lab" vibe, although much of it was decommissioned and replaced with modern service (red herring alert).  In the update the architect specified 208/120 100 amp service for SL and SR (no herring here), below stage level (floor pocket) in power vaults (the orchestra pit and seal room were between them).  Popular band from the 1970s, not my show, call from PA provider about hum/buzz.  "PA is quiet until we connect the monitor split; monitors are quiet until we connect the PA split.  I've used every Pin 1 lift I have, do you have 8?"  PA power is SR, monitor power is SL.

Second is personal, and how I nearly did great bodily harm to another PA provider after I recovered.  "Rock on the Tarmac" at general aviation airport, we're providing additional subs, power, and processing for the subs.  Airport electrician wires in 2 feeders to 2 circuit breakers for 120/240v 100 amp service in a brand new panel in a newly built hanger.  Most of the PA was on one distro, and our sub power and DSP was on a second distro.  Another of those "it's quiet until we put them together" problem.  Audio isolation transformers only changed the sound of the hum; pin 1 lifts were more successful.  I then ask the PA provider if the neutral and ground in each of his distros are unbonded.  "Of course!"  After the show, I do the disconnect at the panel as the electrician is at the other end of the ramp, disconnecting food vendors.  On the second service, the electrician (for reason I'll never understand) stabbed the neutral into the bus bar from the Line bus side.  When I removed it, the neutral feeder wire grazed a line bus 'finger'.  The result was a loud bang and flash (neither of which I remembered immediately after), and a coworker leaning over me asking if I was okay.  Eventually I got up, ears ringing, and followed the feeder to its distro.  I opened the distro, found the neutral and ground bonded (hence the arc flash), so I took my diagonal cutters and installed high impedance air gaps in every conductor, put the cover back on, and vowed to kill that SOB.  Revenge is a dish best served cold and Mother Nature took care of for me a few years later.

So anyone want to guess the problem in the lovey atmospheric theater?

All of this was around 25-30 years ago, and both directly changed the ways I deal with show electrical distribution, how I specify power needs, and how I work as a show electrician.

I get a lot of shit for carefully checking power.  I don't do a gig without using the Extech CT70 it's in my gig box.  I wish that others would invest in them, it even has a tiny 20amp load bank it it!


Anyway Tim, what is a seal room? 

[Ike Zimbel]

Two stories to tell -


Second is personal, and how I nearly did great bodily harm to another PA provider after I recovered.  "Rock on the Tarmac" at general aviation airport, we're providing additional subs, power, and processing for the subs.  Airport electrician wires in 2 feeders to 2 circuit breakers for 120/240v 100 amp service in a brand new panel in a newly built hanger.  Most of the PA was on one distro, and our sub power and DSP was on a second distro.  Another of those "it's quiet until we put them together" problem.  Audio isolation transformers only changed the sound of the hum; pin 1 lifts were more successful.  I then ask the PA provider if the neutral and ground in each of his distros are unbonded.  "Of course!"  After the show, I do the disconnect at the panel as the electrician is at the other end of the ramp, disconnecting food vendors.  On the second service, the electrician (for reason I'll never understand) stabbed the neutral into the bus bar from the Line bus side.  When I removed it, the neutral feeder wire grazed a line bus 'finger'.  The result was a loud bang and flash (neither of which I remembered immediately after), and a coworker leaning over me asking if I was okay.  Eventually I got up, ears ringing, and followed the feeder to its distro.  I opened the distro, found the neutral and ground bonded (hence the arc flash), so I took my diagonal cutters and installed high impedance air gaps in every conductor, put the cover back on, and vowed to kill that SOB.  Revenge is a dish best served cold and Mother Nature took care of for me a few years later.

So anyone want to guess the problem in the lovey atmospheric theater?

All of this was around 25-30 years ago, and both directly changed the ways I deal with show electrical distribution, how I specify power needs, and how I work as a show electrician.

When I was doing this gig https://www.prosoundweb.com/road-stories-5/ the following year. I went over to talk to the genny op (same company, xxxxxx, as mentioned in my other post) about something. He told me he had to go and get something (maybe a ground stake) but the genny was up-and-running and we could hook up whenever, and walked away, with our Cam-Lok tails laying in the grass... I looked around and noticed a mother with a small child playing nearby, and figuring that could end real badly decided that at the very least, I should drape the tails over the metal bumper of the genny (it was one of the small trailer types) so the female ends weren't exposed to tiny exploring fingers. Well, as I did that, one of the hots, the blue one IIRC, hit the bumper and compressed the rubber on the end enough for the brass insert to make contact...also with a very bright flash and bang. On subsequent inspection we discovered that the insert had not been pushed far enough into the rubber boot when it was assembled, so it was only about 1/8" from the end of the boot. Not a great start to the day

[Craig Hauber]

I get a lot of shit for carefully checking power.  I don't do a gig without using the Extech CT70 it's in my gig box.  I wish that others would invest in them, it even has a tiny 20amp load bank it it!


Anyway Tim, what is a seal room?

Was wondering the same thing -and I thought I was up on most oddball theater terms -from opposite coasts and 2 different countries.
Figured it's next to the Otter room but above the Sea Lion room?

I will look into the Extech unit, my Wiggy is starting to wear out. (lol)

[Tim McCulloch]

I get a lot of shit for carefully checking power.  I don't do a gig without using the Extech CT70 it's in my gig box.  I wish that others would invest in them, it even has a tiny 20amp load bank it it!


Anyway Tim, what is a seal room?

A small room/tank with drain, water, and a place to keep the fishy snacks for the seals.  Back in the vaudeville era, "trained seal acts" were popular enough that infrastructure to support marine mammals were built into the venues.

[JohnReeve]

the genny was up-and-running and we could hook up whenever, and walked away, with our Cam-Lok tails laying in the grass...

I'm still new to working with power distribution... I've only been working around that kind of power distribution for a couple of months.

All the times that I have seen tails tied into the wall or a generator, we've hooked them to the distro before energizing them, and I am trying to think about what situations would happen where it's necessary to have power on camlocks before tying them in, but I can't think of them.

Anyhow- is it normal to have "live" cam-lock tails?  Or was the genny operator thinking that the breakers to the legs were open or something? 

[Scott Helmke]

Anyhow- is it normal to have "live" cam-lock tails?  Or was the genny operator thinking that the breakers to the legs were open or something?

No, that is considered (at the very least) to be unsafe.

[Chris Hindle]

Anyhow- is it normal to have "live" cam-lock tails?  Or was the genny operator thinking that the breakers to the legs were open or something?

Not normal, or recommended.
I'll run the cables from my Distro to the panel. At this point, all breakers are off. Hand the tails to Sparky, and watch him (her) like a Hawk. Once connected, go back to my Distro and TEST at the pin sockets (you do own a Fluke or something similar?). If everything looks good, then I power up my rig.
I personally don't believe in making or breaking AC connections under load, even if the connector is rated for it.
Chris.

[Riley Casey]

Proper procedure is to make all connections unenergized, inspect the entire cable / connection run and only then turn on the circuit breaker for shore connections ( shore in this instance means an installed electrical service point )
For generators there is an extra step. After making connections its important to test the service voltages between all legs and the legs and neutral+ground. Large generators can be set up for a variety of industrial loads beyond the usual single phase / three phase 115/208 VAC we are used to.
We for many years had an exceptional special event generator vendor who always sent a trained operator for set up instilling a lot of confidence in all of their customers. One event came up in which our customer hired a generator from a new supplier but assured us that a trained operator would be on hand. Come set up morning - in the dark of course - we provided tails and let the get op do his thing. Started the first chain motor and it moved all of about two feet and poof a bit of magic smoke came out. I checked the front of our PD and all three of the voltage meters were dead. I ran down to the generator and asked what's up. The Gen op said its all good here. I looked at the meters on the genny and found it was set for 460 VAC. The "trained generator operator" turned out to be simply the truck driver.
Trust but verify.

...
All the times that I have seen tails tied into the wall or a generator, we've hooked them to the distro before energizing them, and I am trying to think about what situations would happen where it's necessary to have power on camlocks before tying them in, but I can't think of them....

[ProSoundWeb Community]