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Re: [RFI] 3" ID core for RFI suppression

To: jim@audiosystemsgroup.com
Subject: Re: [RFI] 3" ID core for RFI suppression
From: Howard Lester <howard220@gmail.com>
Date: Wed, 30 Dec 2020 08:31:14 -0500
List-post: <mailto:rfi@contesting.com>
Jim, thank you for your extensive reply and the documents. I’ll save it all, 
figuring I may need to consult with my electrician on these matters. I do trust 
him, that he knows what he’s doing. (He successfully got the Generac generator 
at my previous house to work properly after six years of issues. Three other 
“electricians” couldn’t.) He regularly attends continuing education classes at 
least to maintain his “Master Electrician” title. 

I have an outlet tester from GB Instruments:  
https://shop.ramtool.com/ramtool/en/USD/Hand-Tools/Greenlee-GB/Receptacle-Tester---UL-1%21slashCd-%28Replace-GRT-3500%29/p/GBE-GRT%20500A!plus25000
 
<https://shop.ramtool.com/ramtool/en/USD/Hand-Tools/Greenlee-GB/Receptacle-Tester---UL-1!slashCd-(Replace-GRT-3500)/p/GBE-GRT%20500A!plus25000>
  The result from the tester is “correct.” It tests for reversals and “opens."

I did order the 3” I.D. ferrite core, which is claimed to be Type 31 
(manufacturer unknown) for $25 from KF7P Metalwerks (thank you, Chris Perri, 
for that reference). I figure it can’t hurt, and maybe it will “cure” the 
symptom. Even after I install it, I will need to wait as long as a month before 
I am certain it works, as the symptom is only occasional. 

As for the house wiring, this is a manufactured home built in a factory in 
Pennsylvania in January 2018, and shipped in two pieces to the home site. 
Considering this is made in a factory, can I assume they know to wire up a 
house properly, to code? All the main wiring was done in the factory, not on 
site. I have to assume that, when the two halves were connected on site, that 
“A was connected to A, and B was connected to B.” When my electrician (above) 
installed my 16KW Generac generator here at the new house in October 2018, he 
had to go down into the concrete crawl space do do all the wiring. He commented 
favorably on the house-wiring work. Just what he saw, I don’t know, but 
anything favorable is good.  ;-) But if the issue persists, I’ll see if he’s 
willing to go through the steps you laid out. 

Thank you again.

Howard N7SO


> 
> Howard,
> 
> Before you go around chasing this as RFI, I strongly suggest that you look 
> for wiring errors in the AC power system. Yes, the washing machine is RF 
> susceptible, but that could be caused by an AC wiring problem.
> 
> Things to look for in the AC wiring are: 1)  reversal of phase (hot) and 
> neutral; 2) reversal of neutral and ground (green); 3) using phase and ground 
> to run 120V appliances (by LAW, ground (green) cannot be used as a current 
> carrying conductor; and 4) any connection between neutral and green other 
> than the panel (usually the main breaker panel) where power enters your home.
> 
> Equipment that uses ONLY 240V is properly wired with two phases and green, 
> NOT neutral. 240V equipment may be wired with a neutral ONLY if some part of 
> it runs from 120V.
> 
> Outlet testers will find some of these errors.
> 
> Some things can be checked with a voltmeter. By LAW, all grounds within a 
> premises must be bonded together, and since ground (green) cannot carry 
> power, and because neutral and green may be bonded only at the single panel, 
> we should see some small voltage (tens to hundreds of milivolts) between 
> neutral and green at any outlet when it is supplying power to something (the 
> IR drop from return current in the neutral). If we see no voltage, there's 
> likely a bond between neutral and ground somewhere. If we see no voltage 
> between neutral and green, an ohmmeter check between neutral and green should 
> see that improper short. And if there's no improper bond, the ohmmeter should 
> see the resistance of the two conductors (neutral and green) back to the main 
> breaker panel. And, of course, if we see line voltage (120V) between neutral 
> and ground (green), phase and neutral are reversed.
> 
> One of the wiring mistakes I found in the home I bought 14 years ago here in 
> CA was a string of 120V outlets in the half-kitchen of the "mother-in-law" 
> garage apartment that were powered from one phase and ground of the 240V 
> dryer circuit! In the house, I found an outlet with phase and neutral 
> reversed.
> 
> And I saved the worst for last -- power is fed to most homes as 240V with 
> neutral, but NOT ground (phase, phase, and neutral), and by law, it must be 
> bonded to earth at the entry point. That required bond ran on #12 bare copper 
> (later painted) about 30 ft along a wall to an outlet for a garden hose -- 
> which was fed by PVC pipe. The only connection to earth was a driven rod 
> outside that garage apartment, with about 50 ft of (painted) bare #12 to a 
> breaker panel on the other side of that building. And that panel was fed from 
> the house, so the ground wire was close to 150 ft long. VERY illegal and VERY 
> unsafe.
> 
> You can read more about power systems here, in a tutorial I was commissioned 
> to write for installers of professional audio and video systems. The first 
> link is text, the other two are slides for talks I did at trade shows.
> 
> http://k9yc.com/SurgeXPowerGround.pdf
> http://k9yc.com/InfoComm-PowerSystems2012.pdf
> http://k9yc.com/InfoComm-Grounding2012.pdf
> 
> 73, Jim K9YC
 
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