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If you touch two components and the buzz changes, the equipment is being used as an earth return which is not right.The photo of the receptacle with the wire nut on the earth line, looks too small to me, should at least be the same as the other conductors. I would go through every receptacle and check the connections, especially the earth wires.
I think even though it is a USA model, that they might have used European color coding which is different. IIRC, the wiring made sense. I also checked the chassis with a multimeter and it seemed ok. I will double check. Thanks for your indepth post. Furthermore, I'm 99% convinced it is the Audio circuit after last night with nothing connected and the P3 buzzing away, but when swapped to the Office circuit...nothing. Would you agree this seems to point to the Audio circuit?
Maybe I read the touching the devices on another thread...? sorry.The brown wires at the receptacle, small ones. They appear to end up at the main breaker panel connected to the neutral, or what appears to be a large conductor. Earth wires are tied to what looks like a common earth strip both sides of the switchboard. These brown wires also bond the metal conduits. Why are the brown wires tied to the neutral....this will cause a lot of pain.
One of the reasons I asked to see pictures of the top half of the electrical panel. I want to see how it is fed. Main breaker or MLO. As for the brown wires you mention, they are bare copper wires. The larger bare copper wire you see under the same mechanical lug as the main neutral conductor feeding the panel appears to be the grounding electrode conductor that connects the main neutral conductor to mother earth. (Making the neutral, "The Grounded Conductor"). It appears the grounding electrode conductor travels through a mechanical lug, unbroken, and is bonded, connected, to the panel enclosure which bonds the enclosure also to the now grounded neutral conductor. The small brown wires as you called them, are bare #12, ( looks to be), copper equipment grounding conductors that are terminated on equipment ground bars located on each side of the panelboard. The equipment ground bars are bonded, connected, directly to the panel enclosure. Jim
A newer (Sept 2012) and larger Bill Whitlock paper:An Overview of Audio System Grounding and InterfacingbyBill Whitlock, PresidentJensen Transformers, Inc.Life Fellow, Audio Engineering SocietyLife Senior Member, Institute of Electrical & Electronic Engineershttp://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf
doctorcilantro,You missed the main point of my previous post.These are wired: black/brown (HOT) .. OK.white/blue | yellow/chassis .. Not OK.The white/blue | yellow/ wires should not be bonded, connected, to the chassis of the appliance. In the USA that is a NEC code violation. The Neutral and equipment grounding conductor shall be connected together at the main service equipment and at NO point thereafter.There is also an internal green ground wire coming down out of dishwasher harness that goes to chassis.That is where the green color wire, (the equipment grounding conductor), of the branch circuit feed should be connected to.[/i]The white/blue lead wire of the dishwasher should only be connected to the yellow wire that is the neutral feed from the electrical panel. The two jointed together wires should not be connected to the chassis of the dishwasher.>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>I Still would like to see a picture of the top portion of the electrical panel. Where the big wires that enter the bottom left side of the panel go to at the top of the electrical busing that holds all the branch circuit breakers.As I said in an earlier post, looking at your pictures showing the bottom of the panel is a conduit entry on the bottom left side with 4 wires.* One insulated taped white neutral feed conductor. (Notice the tape color white and not yellow).* Three other insulated black conductors. One with no color tape, just left black. One appears to have red color tape. Last wire is marked with making tape but I cannot make out the color. Just guessing it is blue.What that means there are 3 hot phases.Black wire with no marking tape, phase ( A ).Black wire with red marking tape, phase ( B ).Black wire with Blue marking tape, phase ( C ). Branch circuit breaker connection to bus down each side of the panel.1) A ........... 2) A3) B ............4) B5) C ........... 6) C7) A ........... 8 ) A9) B .......... 10) B11) C ........ 12) CAnd so on.A picture of where the 3 Hot wires go to on the top part of the electrical bus of the panel will verify if the panel is indeed 3 phase 4 wire. Also do the 3 wires connect to a main 3 pole breaker or do they terminate in lugs that are bolted to 3 copper bus. (Main Lug Only)I see the panel is a 42 circuit. Just guessing by the pictures you supplied it looks like a Westinghouse panelboard.On the dead front cover, ( steel cover that covers the breakers), there should be a data plate giving the manufacture name, voltage, phasing, and amperage rating.From the pictures you have shown, the panel, the receptacle pulled from the wall electrical box, the black and white insulated #12 TW wires and the bare #12 equipment grounding wire I would say the original installation was done by US electricians or possibly by Canadian electricians. Time frame? Best guess, roughly 1950s, 1960s.Sure would like to see more pictures of the electrical panel. And maybe the electrical service entrance on the outside of the building. Jim
This leads to all sorts of questions. The straight bare copper wires that run horizontally parallel quite neatly are earth wires, one of them bottom RH corner is a green, assume the rest are earth wires. They terminate on corroded screw terminals directly on the chassis. The brown wires are they bare cables then, yes, earth wires. Whether they bond pipes or are in themselves earthing conductors, should nowhere be connected to the neutral.The OP stated he's in the Middle East, they follow Euro or GB wiring rules (hopefully anyway) 400/415V Star (Wye) 230V to Neutral. His complex at camp runs from a 110V system, so there's a transformer upstream from the distribution board. The neutral should be bonded to the earth at the transformer side, not here at the Dist board. I see this as a lot of earths being bonded to the neutral where they shouldn't be.
The dishwasher pics. The Yellow wire when disconnected from dishwasher chassis, when breaker is powered, is 6V AC - between it and dishwasher chassis. When powered up and running there is no AC on chassis, it measures 0v. I think it follows the Euro standard where yellow or yellow/green is ground. I have not yet inspected the outlet behind the dishwasher.There is a green wire in the dishwasher harness, along with the block and white, that is grounded to chassis (not shown). The wire that is grounded to chassis securely (pic looks like it's not) is the yellow wire from the large white wire which runs to the outlet behind the dishwasher. If I can get back there I could test the cable with multimeter.
Very interesting. Thank you all for the links and input on this. Once we get the panel off here, hopefully more answers. Before that happens, it will be easier for me to inspect the outlets in the room with Audio circuit.Anyone have a guess if this is a ground problem? e.g. Can I cheat my P3 and see if the buzz comes through? Can DC current be minimized with proper grounding schemes? Of two circuits tested, one has a problem. Just curious if this is riding ground, neutral, or both...More pics - what does PH. 3 mean?
doctorcilantro,Pictures are great. Looking at your pictures it appears the white cord is used to power the dishwasher. The white cord plugs into the receptacle at the back of the dish washer. Correct? The white cord has 3 insulated conductors. Brown, Blue, and Yellow. The brown wire connects to the black wire lead from the dishwasher. Brown is the hot conductor.The blue wire connects to the white wire lead from the dishwasher. Blue is the neutral conductor.The yellow wire should be the safety equipment ground wire and should be connected to the chassis. The way it looks now from your pictures the metal chassis is not grounded. For safety to protect from electrical shock it must be grounded.If you want to test for ground continuity of the yellow wire,* Turn off the breaker at the electrical panel that feeds the dishwasher.* Verify, test, make sure the power is off at the dish washer.* Set your multi meter to AC volts on a scale over 120V. Check for voltage from the blue wire, of the white cord, to the yellow wire of the cord. You should read zero volts.* Next set the multi meter to OHMS. Check for resistance/continuity from the blue wire to the yellow wire . You should read short or one ohm or less close to short.Connect yellow wire to chassis. Jim
Still don't have panel open but I was able to test Office circuit HOT to Audio circuit HOT which resulted in 210v. That means the two circuits are on separate legs?
