Re: [LAU] Terrible mic ground noise

On Monday 01 April 2013 08:08:15 Len Ovens did opine: I doubt if it is 'floating', and we've had something resembling the NEC codebook for more than half a century now. What I would be concerned with in a house with wiring old enough to not have the 3rd, round pin in its duplexes, would some folks, and I have found this before in my travels, that the wider of the two slots in the duplex, which was supposed to be connected to the white wire which in post knob & ball wiring days, was always assumed to be the neutral side of the wiring. The black wire was supposed to be connected to the narrower slot, and was assumed to be the hot side of the line. By electricians... I can drive to what was a greasy spoon about a mile from here, in an old frame building, where every appliance in the kitchen was hot enough to buzz the help, the whole damned building is wired backwards! She finally moved her business about 2 years ago, into a much more modern building. THE IMPORTANT PART of this msg: At the lumberyards, like Lowes or Home Depot, in the electrical aisle, they have shirt pocket sized electrical 'Sniffers" not much bigger than a pen or pencil. Often their power switch is the pocket clip, you grab the end and squeeze the clip shut, then the other end has a plastic coated blade, and it will trill like a canary & blink an LED you can see when that blade is within 1 to 2 inches of a live wire. They sell for something in the ten dollar range, very cheap for something that can save your life by finding hot stuff that isn't supposed to be, like your refrigerator, often installed within reach of the usually well grounded stuff of the kitchen sink? So please get one ASAP. If not sooner. /THE IMPORTANT PART. The rest is optional but hopefully educational. I have 2, and they have saved me from many a potentially lethal shock over the last 25 years from stuff that was wired by folks who claimed to have known what they were doing. If you find a reverse wired duplex, where the wider slot is the hot side, it was probably wired bass-ackwards and has been since a roll of wire came on the premises 65 years ago. Yes, its been that long since I wired my parents house for electricity as it was being built in 1947. I was then 13 yo. Not knowing the white was ground by convention in the electrical trade, and already used to a grounded wire in a radio being black since I was already doing radio service for smoking money back then, I did it backwards & had to go back and fix it a month later when we were wiring the crawl space dugout for a water pump, the pump was a people buzzer when turned off. One of the steps in the education of Gene, who has now chased electrons to make therm do useful work all his life since, the last 50 in broadcasting. Oh, and I haven't had a cigarette now for 25 years. quit cold turkey, sick of being half sick with a cold that seemed to have hung on for more than its allotted 2 weeks. Maybe. One of my boyhood best friends followed in his fathers footsteps and got his Journeyman's card by the time he was 20. I had a problem & called him in on it (somehow life had put us back in the same town) when he was about 45, because I was at the time up to my butt in alligators as I had just become the CE at a tv station & the wiring to the studio lights was being a smoking problem child. Electrical stuff letting out the smoke usually means keeping fire extinguishers handy... He came in, we made all sorts of measurements & did a lot of head scratching for a couple hours one afternoon, then sat on the back stoop & had a beer, still playing what if games but reached no consensus as to why were were measuring many times the expected current in the neutral wires of one electrical box but not the other, the source of all the smoke & sparks. He was stumped as was I ATT. So I went home to dinner, still thinking about it, and the lights came on while I was scarfing up a hamburger steak. I went in about 5AM Sunday morning & verified the error. One of those 2 boxes was miss wired. Hard to fix as there wasn't a big breaker to kill the whole box that was miss wired, so I had to work on it hot. NBD to me. The problem was related to it being a 3 phase system. There was about 50 kw worth of lights in the studio in those days so there was 2 boxes full of 15 amp breakers. One box was a Federal, one box was a Square-D. I forget now which was which, but one box ran one phase A down the column of breakers on the left, and phase B down the 2nd column of breakers on the right, and one boxes bus was formed like a pair of combs teeth facing each other positioned between the teeth of the other phase, so that the top row was fed by phase one, the next row by phase 2, the 3rd row back on phase 1 etc to the bottom of the box. The electricians? who wired it weren't cognizant of the differences that would make and blindly wired both boxes so that the lamps, 1500 watt halogens, were wired up with a pair of 12 gauge wires to the hot side, and a single 14 gauge wire bringing the neutral back for BOTH lamps. So one box had 29 amps coming back up the flea weight 14 gauge neutral because both lamps were on the same phase, where the other box only had about 3.5 amps on this same neural wire because thats about what you get when you do the vector math for 2 legs of a 3 phase system. So the solution was to remove the right hand top wire, move it to the left hand side at row 2, take that wire back to the top right breaker, and basically do a step & repeat till I got to the bottom of the box. The breakers themselves could have been moved, easier, except that would have tangled up the wires even worse & the connections needed tightening anyway. Just good practice IMO. Problem solved for the life of the facility. Wrong boxes in the first place, should have been 3 phase boxes, but it was built by idiots working on the cheap & they would probably have had to special order the correct 3 phase boxes. A good electrician should have grokked that little detail instantly. But the vector math for a 3 phase system was not in his knowledge banks at all even if he was working days at one of the coal fired power station facilities being expanded that light up Los Angeles at the time, time being the late 1970's, place being Farmington NM. I never had the heart to tell him that his education was incomplete. Life leads folks down an infinite multitude of paths, always according the the Peter Principle I think. Or is that Parker? Never could (shrug) keep those 2 guys straight. [...] Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> is up! My views <http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml> "Plaese porrf raed." -- Prof. Michael O'Longhlin, S.U.N.Y. Purchase I was taught to respect my elders, but its getting harder and harder to find any...