The inspectors who look over your installs only have hammers, so only look for nails.
You and I are in the same boat.
I however, have only one AHJ to worry about. Over the years, they have received information from me describing the anomolies caused by following the intent of code where specifics do not exist, as well as alternative solutions which still meet the intent as well as the safety. As well, I detail to them when they are incorrect, but again, always with alternative solutions for them to select from or modify.
Pushing the AHJ up against the wall never works.
John
While some industries (hospital), some corporations and some localities about the ground pin being up or down, there is no NEC or UL rule about this matter.
On the NEC rules forum it's a verboten subject.
You can measure -130dB THD too, I would like to see data from refereed DBT maybe the AES has already done some. Input from people with something to sell is taken with a grain of salt.
Just for fun you should try it with a Fire Marshal!
I do, it's part of the job. We have our own fire department. They also perform vertical flame tests for us when the cables we need are not tray or UL listed.
John
During I believe the '08 Code convention on the last day at the entire group meeting the issue of an advisory was brought up from the floor to put the safety pin up as metal sliding down the wall would hit it first. This was passed on a voice vote as an advisory.
It ran contrary to the almost universal practice at the time for ground pin down. The reason ground down became almost universal is that the early 3 pin outlets would break the insulation on the top edge if the pin was up and the cord yanked out. The rigid plastic was thin at the edge of the ground pin and easily broken. Most folks realized if you put the pin down that didn't happen.
Been a very long time since the outlets were that crappy and younger folks never had the issue.
But in my shop as the outlets are above 36" off the ground we do pin down.
Then there was the concert promoter who ignored the Fire Marshal counting people entering the theatre. When the 500 folks had entered as listed on the building's occupancy permit, the Marshal instructed the door men to admit no one else. The promoter told them to ignore the guy and let in anyone who had tickets. Well when number 501 entered, the Marshal had the local police close down the venue and remove everyone.
You never tick off a Fire Marshal they are not bound by any code.
So now, in the event that I happen to have a ""piece of metal sliding down the wall"" such that it hits the plug cleanly, I now have to worry that the initial contact breaks the grounding pin, leaving the appliance at the other end of the cord lacking a safety bond. Especially if that same piece of hypothetical metal remains in place after breaking the ground pin, but is now making a connection between the hot blade which did not shear, and the nub of the safety pin remaining on the cord thereby energizing the entire metal enclosure of the appliance to 120.
Wonderful.
You know, seems to me that happened just the other day...sigh..
John
stranger things happen. Like when the large telco I worked with put in a new distribution board as they were so on the limits half the corridor lights had to be turned off. When a 450A 3phase distribution board is powered up having not been wired correctly OR checked the bang is spectacular. The shouting even more so. 750A cart fuses are unforgiving in what they melt before they die. Not sure that subby got any more work from them...
But seeing the mess made me glad I don't work with that stuff.
But seeing the mess made me glad I don't work with that stuff.
regarding LF and mastering:
in disc mastering I am sure pretty much everyone is aware of the limitations of the media, ya gotta keep it in the groove in playback. So LF extension and level can become problematic.
In the digital domain, it should be a non-issue technically, and it is. Except for the humans that interfere with tech specs and want maximum loudness. By limiting the LF extension you can get your modulation index higher, ie louder. You aren't "wasting" the space on "things no one is going to hear". So, for mastering for mainstream and pop, there is a tendency to limit the LF extension so there is more room elsewhere for loudness.
I spent 25+ years doing FM radio processing and have dealt with this personally. It can make a significant difference to the perceived loudness. And that is all important.
Cheers
Alan
in disc mastering I am sure pretty much everyone is aware of the limitations of the media, ya gotta keep it in the groove in playback. So LF extension and level can become problematic.
In the digital domain, it should be a non-issue technically, and it is. Except for the humans that interfere with tech specs and want maximum loudness. By limiting the LF extension you can get your modulation index higher, ie louder. You aren't "wasting" the space on "things no one is going to hear". So, for mastering for mainstream and pop, there is a tendency to limit the LF extension so there is more room elsewhere for loudness.
I spent 25+ years doing FM radio processing and have dealt with this personally. It can make a significant difference to the perceived loudness. And that is all important.
Cheers
Alan
I related the story a while back of the megawatt chemical laser facility that TRW had in Capistrano Beach CA. To meet their power needs they had PG&E (?) bring in 23kV 3 phase and they rectified it directly inside the substation. A messy business when the electricians got the custom rectifiers in wrong.
You know it's bad when you receive a call from several seismograph operators in neighboring countries asking you if something happened 300 feet below you.
John
Richard, thanks for the hint about Benchmark digital measurements. I went to their website and found a very complete comparison between two D-A converters that they made and how they improved things over the years. Their app notes were written by their VP John Siau, who appears to have both the test equipment and the ears to hear differences. Siau makes a careful remark about other, much cheaper D-A units and implies how bad they really are in reality. I believe him, because he even showed a meaningful comparison between their older design and their newer one. I wonder what the cheap units look like in comparison. He can't show it, but maybe we can with our up-to-date test equipment. As to hearing differences, I do, and many here don't, so be it.
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Yes, they make very good equipment. The old unit was already ridiculously better than we can hear, thus no actual comparative listening test data. Nor anything to support Richard's dubious claims about jitter.
Still, it's refreshing to see expensive equipment that's engineered rather than "designed."
Yeah. That's serious. I always wonder how far away it was detected when JET used to hop on a plasma quench.
Or LIGO. I don't know if I'll get over this, the head of instrumentation engineering at LIGO just called our CTO and asked to talk to the designer of the AD797. Apparently it was a key component (in his words).
Just think, I helped.- Status
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