- Feb 12, 2006
- 61,049
- 5
- 221,003
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
And cost you money. There's lots of blame that gets tossed around, I want my bases covered.
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Yes. We noticed that when we did a test drive.
We intentionally went a bit larger than the phone booth size you see a lot of places.
We also get some movable/removable acoustic foam so hopefully we can keep it from being too dead.
The room we got specs isolation at about -46db (1KHz). I measured the isolation in the area they use now and it was an abysmal 13db difference with the door open vs closed. It's like, "tell the people in the next room (which is a classroom) to keep quiet." Not good at all.
Back when we were doing television remote broadcasts on a regular basis, we usually saw the ground loops in the video before we noticed them in the audio. But fix it one place and it got fixed everywhere.
I might have had to work, nights and weekends on those gigs, but they were are the most fun, though sometimes also the most stressful. We had a great staff and a lot of very motivated students on the crew. Many of whom went on to bigger and better things in the business.
In all the years of that I only missed one remote. It was the day my daughter got married.
But I did manage to put in an appearance. What with being all suited up in a tux, how could I not?
If you want to see the worst wiring in the world, come to Montana where an electrical inspection is when you call an inspector to a site, they drive by the building a week later to see if it burned down or not.
Those that aren't burnt up, pass the test. I've seen water pipe used as the common return leg back to the service panel. Most time the west side of a kitchen will be on one leg and the east side one the other.
The house I'm in had several circuits with the white and black reversed. I fix them as I find thrm..... by my music room is correct.
I swear.... the electricians here are deaf and blind and they use guide dogs to bark once for white and twice for black.
An interesting lawsuit there!
When a lineman touches a wire that's supposed to be open from the generating station and instead he dies because you've back-charged it and dies.......
Yup! ^
As long as everyone involved and everyone impacted knows what they are doing, and what's going on, and follow all of the appropriate precautions, things would be OK.
But it is a rare occurrence that any of that would occur, so it's a bad idea to screw with this stuff and assume it will be OK.
At work we used to joke about this one guy who was a self professed (yet unlicensed) electrician.
The joke was. If you don't touch it, it won't Hertz ya.
He moved on and later got his license. I saw some if his work after that.
The joke was still appropriate.
I dont care who supplies the power.
After my OWN polarity test, i plug into a tested-good 20Amp circuit with my 30 foot 10 ga extension cord with a 20 Amp GFCI Hospital Grade receptacle on the end.
Then that goes into my Furman PL-8 where all my musical gear receives power.
Personal lighting.... if I run any, comes directly out of the GFCI box.
I had to work on internal 480 and 25KVA systems in a major L.A. hospital and the guy I trained under was an old Merchant Marine Electrician who taught me many things.
Primary lesson: NEVER TRUST THE WHITE WIRE.
While working on a major remodel job in a huge house, I was tracking down some 110 V circuits with a tool that connects to a live circuit at any convenient outlet that places a signal on the wires and you use a detector at the breaker panel to identify the breakers powering various circuits in order to turn off, and lock out the breakers on the affected circuits to allow the safe demolition of some walls, while leaving other circuits in the house energized.
The tool inductively picks up a signal generated by the remote transmitter as you pass the receiver along each breaker in the panel. When the beeping signal is the loudest, you have found the breaker. You turn the breaker off, and the beeping stops because the transmitter is no longer being powered.
The problem I encountered was that someone had connected two hot wires originating from two different breakers, (on the same phase), in a ceiling light fixture box up on the second floor, so that I had to flip two 110 V breakers to de-energize the circuit. Yikes! I used a different, battery powered wire tracing tool to find the miswire, but it took a couple hours to find.
Surfer Joe46 said: "NEVER TRUST A WHITE WIRE". When working in any junction or device box, as I remove wire nuts, and disconnect junctions, I use a neon tester on all combinations of wires to make sure everything is de-energized.
The tool inductively picks up a signal generated by the remote transmitter as you pass the receiver along each breaker in the panel. When the beeping signal is the loudest, you have found the breaker. You turn the breaker off, and the beeping stops because the transmitter is no longer being powered.
The problem I encountered was that someone had connected two hot wires originating from two different breakers, (on the same phase), in a ceiling light fixture box up on the second floor, so that I had to flip two 110 V breakers to de-energize the circuit. Yikes! I used a different, battery powered wire tracing tool to find the miswire, but it took a couple hours to find.
Surfer Joe46 said: "NEVER TRUST A WHITE WIRE". When working in any junction or device box, as I remove wire nuts, and disconnect junctions, I use a neon tester on all combinations of wires to make sure everything is de-energized.
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A 30 ft 10 ga extension extension cord? Really?
Sure! Makes moving the amp from the outlet side of the cord a lot easier.
- Feb 12, 2006
- 61,049
- 5
- 221,003
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
I don't se many 10 gauge extension cords not pulling out of receptacles due to weight and stiffness. Also, many 5-15 plugs will not accept 10 gauge (practically as well as legally)
Yep,
Still have my ancient "Fox and Hound" tester.
My dad taught me basic electrical wiring with the "one hand in your back pocket rule", meaning, you probably would not have current passing through your heart if only one hand was involved and you were wearing a long sleeve shirt.
I did look up the specs for our old truck "Big Mo" mobile recording.
It was a UL listed isolation transformer although I only recall 1 inspector looking inside the weather proof box we made to keep the transformer at the rear of the 28' Mercedes box truck. Of course it had multiple taps as you never really knew what the voltage supply would be from venue to venue.
The worst part; and I think you big PA guys have/had the same issue, was connecting to building power.
We could almost never find a panel with space to tie in a 60 Amp 2-pole breaker even though we had a collection of Square D, Cutler Hammer, Westinghouse, etc. breakers for the occasional time we could do something legally.
We used these Tico jaw clamp connectors that would allow the threaded jaws to clamp down on a main lug in a panel.
We then went with a short SO cord to our own small panel box with twist locks on both ends.
That 8' of cable was always energized with no protection so supporting it was paramount.
We did hundreds of shows with that truck without incident although that didn't make it right.
Andy, did you guys also have some dicey tie in to panels back in the day?
After reading through the thread I have a couple of questions. Say I am at a gig and my amp is plugged into a 3 prong receptacle that tests good with both of these type testers.
The sound man approaches me with a XLR cable to plug into the back of my amp. He is using a separate outlet and the outlet he is using also tests good with both type testers.
Is it safe to say there will be no issues assuming that the cable connecting my amp to the board is not faulty ?
If the answer is yes, what if a keyboardist and a guitarist are also running a line to the board, and each of them are using a separate receptacle to power their gear, and both receptacles they are using test okay with both types of tester. Again assuming no faulty cables are being used, are we good to go ?
100% sure ?
The sound man approaches me with a XLR cable to plug into the back of my amp. He is using a separate outlet and the outlet he is using also tests good with both type testers.
Is it safe to say there will be no issues assuming that the cable connecting my amp to the board is not faulty ?
If the answer is yes, what if a keyboardist and a guitarist are also running a line to the board, and each of them are using a separate receptacle to power their gear, and both receptacles they are using test okay with both types of tester. Again assuming no faulty cables are being used, are we good to go ?
100% sure ?
Yup! You can buy them at (shudder) Harbor Freight.... but I make my own.
IF - and there's the qualifier --IF the ground pin is on the UP SIDE of the receptacle, then the weight is borne by the ground pin more than normal. This is a standard in hospitals and I think in any wall receptacle that's over 18" from the floor.
BTW: Hospital grade plugs and receptacles are 5 lb pull per pin. That's a 15 lb combined pull.
That keeps grandma's defibrillator from being kicked (accidentally or not) out of the wall.
Too true. But a commercial establishment should be 20 Amp service.
The male end of my extension cord is one of these:
Attachments
I would say that you should have a high confidence level employing the method you have described, but to be even more "belt and suspenders" sure, you could also employ a two wire neon lamp tester to test for a difference in potential between the grounded parts of cables originating from two different pieces of equipment. You could also use a screwdriver style capacitively coupled neon tester to sense voltage on a grounded part of a single cable. The ionization Voltage of neon is about 60 VAC, and maybe 90 VDC, so this type of tester would not detect a fault that presented voltages below that magnitude.
I posted earlier about how to use a three wire extension cord to extend the conductors from receptacles that are located with some distance between them, so that you can test for a difference in potential, (voltage) between the hot, grounded, (neutral), and grounding conductors.
If I was not in the US, but some third world, or notoriously unsafe country, I might employ all of the tests, and maybe include some visual inspection of my own before risking damage to very expensive equipment. Even though I am aware of how to, and have all the tools needed to check out venue power, I have to admit, that we have not made it a practice to even use the basic outlet tester we always carry with us the first time we are at any venue.
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The little testers can't detect bootleg grounds
This
99.999%
When stop using the testers because you get tired of using the testers because all you ever find is safe situations
Your risk rises to 99.99%
The .01% gets discussed to no end. A lot of gear manufacturers understand the .01% figured into their engineering and warranty
This
99.999%
When stop using the testers because you get tired of using the testers because all you ever find is safe situations
Your risk rises to 99.99%
The .01% gets discussed to no end. A lot of gear manufacturers understand the .01% figured into their engineering and warranty
